JP6639053B2 - Glass, optical glass, phosphate optical glass, glass material for polishing, glass material for press molding, and optical element - Google Patents

Description

  The present invention comprises a first invention and a second invention. The first invention relates to a phosphate optical glass having excellent transmittance, high dispersion, and a suppressed increase in refractive index, and an optical element made of the phosphate optical glass. Further, the second invention relates to glass, optical glass, glass material for polishing, glass material for press molding, and an optical element which can easily reduce the reduction color.

  A high-dispersion glass lens is used for correcting chromatic aberration by forming a pair lens in combination with a low-dispersion glass lens. High dispersion glass generally has a high refractive index, and low dispersion glass generally has a low refractive index. Therefore, when a pair lens is formed by combining the two, there is a problem that a large difference in refractive index causes a strong curvature of field.

  For example, Patent Literature 1 discloses a glass having a low Abbe number νd, that is, a high-dispersion glass. However, since the refractive index is too high, a problem of field curvature occurs when used in the above-mentioned pair lens.

In addition, the high dispersion glass usually contains a large amount of components such as TiO ₂ , Nb ₂ O ₅ , WO ₃ and Bi ₂ O ₃ (hereinafter sometimes referred to as “high dispersion component”) as glass components. are doing. These highly dispersed components are easily reduced in the glass melting process. When the high dispersion component is reduced, the glass absorbs light on the short wavelength side in the visible light range, and causes coloring (hereinafter, sometimes referred to as “reduced color”) on the glass.

  In Patent Literature 2, such coloring of the glass is reduced by heat-treating the glass. It is considered that this is because visible light absorption is weakened by oxidizing ions such as Ti, Nb, W, and Bi in a reduced state by heating.

That is, in a highly dispersed glass containing a large amount of highly dispersed components such as TiO ₂ , Nb ₂ O ₅ , WO ₃ and Bi ₂ O ₃ as glass components, the required transparency is reduced by reducing the reduction color by heat treatment. Obtainable. However, in this heat treatment, it is necessary to heat the glass for a long time, so that improvement is required from the viewpoints of productivity and economy. In particular, highly-dispersed glass having an Abbe number ν _d of 18.1 or less is colored more intensely, so that a long time is required for heat treatment for reducing coloring.

JP 2013-212935 A JP-A-6-345481

  In view of such circumstances, a first object of the present invention is to provide a phosphate optical glass having excellent transmittance, high dispersion and a suppressed increase in refractive index, and a phosphate according to the first invention. It is an object to provide an optical element and an optical glass material made of optical glass. A second object of the present invention is to provide a glass capable of shortening the heat treatment time when reducing the reduced color by heat treatment.

As a result of intensive studies to achieve the above object, the present inventors have adjusted the content ratio of various glass components (hereinafter, referred to as glass components) constituting glass for the first problem. As a result, they found that the object could be achieved, and based on this finding, completed the first invention. As for the second problem, it has been found that the object can be achieved by adding Li ₂ O at a predetermined ratio to the highly dispersed component, and based on this finding, the second invention has been completed. I came to.

That is, the gist of the present invention is as follows.
(1) Abbe number νd is 16.70 or less;
The refractive index nd is 2.1000 or less,
P ₂ O ₅ , TiO ₂ and Nb ₂ O ₅ ,
A phosphate optical glass having a mass ratio [TiO ₂ / Nb ₂ O ₅ ] of TiO ₂ content to Nb ₂ O ₅ content of 0.15 or more.
(2) The phosphate optical glass according to (1), wherein the content of Bi ₂ O ₃ is 29.0% by mass or less.
(3) Abbe number νd is 16.70 or less;
The content of Bi ₂ O ₃ is 29.0% by mass or less,
A phosphate optical glass having a total content of TiO ₂ , Nb ₂ O ₅ and WO ₃ of 45.0% by mass or more.
(4) The mass ratio of the total content of TiO ₂ and WO _{3 to} the content of Nb ₂ O ₅ [(TiO ₂ + WO ₃ ) / Nb ₂ O ₅ ] is 0.15 or more (1) to ( The phosphate optical glass according to any one of 3).
(5) A glass material for press molding comprising the phosphate optical glass according to any one of (1) to (4).
(6) An optical element comprising the phosphate optical glass according to any one of (1) to (4).
(7) Abbe number ν _d is 18.10 or less;
The total content of TiO ₂ , Nb ₂ O ₅ , WO ₃ and Bi ₂ O ₃ [TiO ₂ + Nb ₂ O ₅ + WO ₃ + Bi ₂ O ₃ ] is 30% by mass or more, and the content of Bi ₂ O ₃ is 38% by mass. % Or less phosphate glass,
Content of Li ₂ O, TiO _2, Nb ₂ O _5, the mass ratio of the total content of WO ₃ and _{Bi 2 O 3 [Li 2 O} / (TiO 2 + Nb 2 O 5 + WO 3 + Bi 2 O 3)] Is a glass wherein the value obtained by multiplying by 100 is 0.015 to 0.770.
(8) the Abbe number ν _d is 18.10 or less;
A phosphate glass containing at least one oxide selected from TiO ₂ , Nb ₂ O ₅ , WO ₃ and Bi ₂ O ₃ ,
Under air atmosphere, remelt and mold at a temperature of 110 to 120 ° C. higher than the liquidus temperature LT for 90 minutes,
In an air atmosphere, the glass obtained by keeping at a holding temperature of 0 to 20 ° C. lower than the glass transition temperature Tg for 15 minutes and gradually cooling at a temperature lowering rate of 30 ° C./h to a temperature 120 ° C. lower than the holding temperature is 17 mm long, In the thing processed to 13mm in width and 10mm in thickness,
In a top view, a portion that is a distance of 0 to 5 mm from a vertical edge and a range of 0 to 5 mm from a horizontal edge is defined as a glass edge,
In a top view, when a portion that is a distance of 6 to 11 mm from a vertical edge and a range of 4 to 9 mm from a horizontal edge is a glass center portion,
When incident light parallel to the thickness direction, the external transmission of the glass edge T _A and the external transmittance T _B is formula of the glass center (2) with a value above T ₁ is calculated at a wavelength of 656nm ,And,
Until said difference between the external transmittance T _A of the glass edge and the external transmittance T _B of the glass center (T _A -T _B) is 5% or less,
Heat treatment in an air atmosphere at a heating rate of 100 ° C./h and holding at a heat treatment temperature of 5 to 15 ° C. lower than the glass transition temperature Tg, and at a cooling rate of 30 ° C./h to a temperature of 120 ° C. lower than the heat treatment temperature When the slow cooling process of slow cooling is repeated once or multiple times,
Glass wherein the total holding time at the heat treatment temperature in the heat treatment is within 48 hours.
T ₁ = 0.83 × [1-[(n _C -1) / (n _C +1)] ² ] ² × 98 (2)
In [Equation (2), n _C is the heat treatment until the difference between the external transmittance T _B of the external transmittance T _A and the glass center of the glass edge (T _A -T _B) is less than 5% And a refractive index at a wavelength of 656.27 nm when a slow cooling process is performed. ]
(9) The glass according to (7) or (8), wherein the content of Li2O is 0.010% by mass or more.
(10) The glass according to any one of (7) to (9), wherein the content of Li2O is 0.640% by mass or less.
(11) The glass according to any one of (7) to (10), wherein the value of βOH shown in the following formula (1) is 0.05 mm −1 or more.
βOH = − [ln (D / C)] / t (1)
[In the formula (1), t represents the thickness (mm) of the glass used for measuring the external transmittance, and C represents the external transmission at a wavelength of 2500 nm when light is incident on the glass in a direction parallel to the thickness direction. D represents the external transmittance (%) at a wavelength of 2900 nm when light is incident on the glass in a direction parallel to its thickness direction. ]
(12) The glass according to any one of (7) to (11), containing Nb2O5 as a glass component.
(13) The glass according to any one of (7) to (12), containing TiO2 as a glass component.
(14) An optical glass comprising the glass according to any of (7) to (13).
(15) A polishing glass material comprising the glass according to any one of (7) to (13).
(16) A glass material for press molding comprising the glass according to any one of (7) to (13).
(17) A polishing glass material comprising the optical glass according to (14).
(18) A glass material for press molding comprising the optical glass according to the above (14).
(19) An optical element comprising the glass according to any one of (7) to (13).
(20) An optical element comprising the optical glass according to (14).
(21) An optical element comprising the polishing glass material according to (15) or (17).
(22) An optical element comprising the glass material for press molding according to (16) or (18).

According to the first aspect, when a pair lens is formed by combining with a low dispersion glass lens, the difference in Abbe number is large, so that a high effect is obtained in correcting chromatic aberration. Further, even when a pair of lenses is combined with a low-dispersion glass lens having a low refractive index, the field curvature is suppressed because the difference in refractive index is small.
According to the second aspect, when reducing color is reduced by heat treatment in the high dispersion glass, the heat treatment time can be shortened.

  Hereinafter, embodiments for implementing the present invention (hereinafter, simply referred to as “embodiments”) will be described in detail. The following embodiment is an exemplification for describing the present invention, and is not intended to limit the present invention to the following contents. The present invention can be appropriately modified and implemented within the scope of the invention. Further, the description of the duplicated portions may be omitted as appropriate, but does not limit the gist of the invention. In the present specification, the “optical glass” is a glass composition containing a plurality of types of glass components (glass components), and unless otherwise specified, the form (lumps, plates, spheres, etc.) It is used as a general term regardless of the purpose (material for optical element, optical element, etc.) and size. That is, the form, use, and size of the optical glass are not limited, and any form of optical glass, any kind of optical glass, and any size of optical glass are included in the optical glass of the present invention. In this specification, the optical glass may be simply referred to as “glass”.

  Further, in this specification, a numerical value range may be represented as “(numerical value 1) or less” using (numerical value 1). The range represented in this way is a numerical range obtained by combining a numerical range smaller than (numerical value 1) and (numerical value 1). The numerical range represented as “less than (numerical value 1)” is a numerical range smaller than (numerical value 1) and does not include (numerical value 1). A numerical range may be represented by using (numerical value 2) such as "(numerical value 2) or more". The range represented in this way is a numerical range obtained by combining a numerical range larger than (numerical value 2) and (numerical value 2). A numerical value range may be represented as “exceeding (numerical value 2)”. The range represented in this way is a numerical range larger than (numerical value 2) and does not include (numerical value 2).

  In the present specification, the optical glass according to the present invention will be described mainly based on the content of each glass component in mass%. Hereinafter, unless otherwise specified, “%” represents% by mass. For some glass components, the content in cation% is also described.

  In this specification, the expression “% by mass” means, for each glass component represented by an oxide or a fluoride, the content of each glass component when the total content of all the glass components is 100 mass%. Means to display. Further, the total content in terms of mass% refers to the total content of a plurality of types of glass components (including the case where the content is 0%). The mass ratio refers to a ratio (ratio) between contents of glass components (including a total content of a plurality of types of components) in terms of mass%.

  Further, in this specification, the cation% display means a mole percentage when the total content of all the cation components is 100%. The total content in cation% is the total content of a plurality of types of cation components (including the case where the content is 0%). The cation ratio refers to a ratio (ratio) of the content of cation components (including the total content of a plurality of types of cation components) in cation% display.

The valence of the cation component (for example, the valence of P ⁵⁺ is +5, the valence of Si ⁴⁺ is +4, and the valence of La ³⁺ is +3) are values determined by custom, and the P, Si, when notation La on an oxide basis, is the same as denoted by _{P 2 O 5, SiO 2,} La 2 O 3. Therefore, when analyzing the glass composition, it is not necessary to analyze even the valence of the cation component. Further, the valence of the anion component (for example, the valence of O ²⁻ is −2) is also a value determined by a custom, and as described above, the glass component on an oxide basis is, for example, P ₂ O ₅ , SiO ₂ or _{It is the same as described as 2} O ₃ . Therefore, when analyzing the glass composition, it is not necessary to analyze even the valence of the anion component.

As described later, Sb ₂ O ₃ , SnO ₂ , and CeO ₂ may be added in small amounts to glass as a fining agent. However, in this specification, the total content of all glass components does not include the content of Sb ₂ O ₃ , SnO ₂ and CeO ₂ . That, Sb ₂ O ₃ in the glass component, SnO _2, each content of CeO ₂ is, Sb ₂ O _3, SnO ₂ and Sb in a total content of all glass components other than CeO _{2 2} O _3, SnO ₂ , CeO ₂ . In the present specification, such a notation is referred to as “outside division”.

  Hereinafter, a first embodiment and a second embodiment of the present invention will be described. The first embodiment is an embodiment of the first invention, and the second embodiment is an embodiment of the second invention.

1st Embodiment 1-1 embodiment and 1-2 embodiment (it may be collectively called "1st Embodiment" hereafter) are explained in full detail.

  The glass composition of the optical glass according to the first embodiment can be determined by ICP-AES (Inductively Coupled Plasma-Atomic Emission Spectrometry) or ICP-MS (Inductively Coupled Plasma-Mass Spectrometry). The analysis value obtained by ICP-AES may include, for example, a measurement error of about ± 5% of the analysis value. Further, in the present specification and the present invention, a content of 0% or no glass component means that the component is not substantially contained, and the content of the component is substantially equal to the impurity level. Indicates that:

1-1 Embodiment The optical glass according to a 1-1 embodiment of the present invention includes:
Abbe number νd is 16.70 or less,
The refractive index nd is 2.1000 or less,
P ₂ O ₅ , TiO ₂ and Nb ₂ O ₅ ,
A phosphate optical glass having a mass ratio [TiO ₂ / Nb ₂ O ₅ ] of TiO ₂ content to Nb ₂ O ₅ content of 0.15 or more.

  Hereinafter, the optical glass according to Embodiment 1-1 will be described in detail.

  In the optical glass according to Embodiment 1-1, the Abbe number νd is 16.70 or less. The upper limit of the Abbe number νd is preferably 16.68, and more preferably 16.66, 16.64, 16.62, 16.60, 16.58, 16.56, 16.54. Further, the lower limit of the Abbe number is preferably 15.50, and the larger the value is in the order of 15.55, 15.60, 15.65, 15.70, the more preferable.

  When the Abbe number νd is 16.70 or less, the difference in Abbe number increases when a pair lens is used in combination with a low-dispersion glass lens, and a high effect is obtained in correcting chromatic aberration.

  In the optical glass according to Embodiment 1-1, the refractive index nd is 2.1000 or less. The upper limit of the refractive index is preferably 2.0950, and further in the order of 2.0900, 2.0850, 2.0800, 2.0750, 2.0500, 2.0300, 2.0100, 2.000. Is more preferable. In addition, the lower limit of the refractive index is preferably 1.8800, and the larger the value in the order of 1.9000, 1.9200, 1.9400, and 1.9600, the more preferable.

  By setting the refractive index nd to 2.1000 or less, even when a pair lens is used in combination with a low-dispersion glass lens having a low refractive index, field curvature is suppressed because the difference in refractive index is small.

The optical glass according to the 1-1 embodiment includes a P ₂ O _5, TiO ₂ and Nb ₂ O _5. By containing P ₂ O ₅ , TiO ₂ and Nb ₂ O ₅ , it is possible to obtain an optical glass with high dispersion and a suppressed increase in the refractive index nd.

In the optical glass according to Embodiment 1-1, the mass ratio of the content of TiO _{2 to} the content of Nb ₂ O ₅ [TiO ₂ / Nb ₂ O ₅ ] is 0.15 or more. As described above, the optical glass according to Embodiment 1-1 includes P ₂ O ₅ and TiO _2. However, increasing P ₂ O ₅ and TiO ₂ lowers the melting property of the glass and increases the liquidus temperature. The problem of rising occurs. Therefore, by including Nb ₂ O ₅ contributing to high dispersion at a specific ratio with respect to TiO ₂ , an increase in the liquidus temperature was prevented, and this problem was solved.

In the optical glass according to Embodiment 1-1, the lower limit of the mass ratio [TiO ₂ / Nb ₂ O ₅ ] between the content of TiO _{2 and} the content of Nb ₂ O ₅ is preferably 0.16, Furthermore, it is more preferable in the order of 0.17, 0.18, 0.19, 0.20, 0.23. The upper limit of the mass ratio [TiO ₂ / Nb ₂ O ₅ ] is preferably 4.50, and furthermore, 4.40, 4.30, 4.20, 4.10, 4.00, 3.80. , More preferably 3.60.

In the optical glass according to Embodiment 1-1, when the content of the glass component is represented by cation%, the cation ratio [Ti ⁴⁺ / Nb ⁵ ] between the content of Ti ^{4+ and} the content of Nb ^{5+. +} ] Is preferably 6.00, and more preferably 5.90, 5.80, 5.70, 5.65, 5.60. The lower limit of the cation ratio [Ti ⁴⁺ / Nb ⁵⁺ ] is preferably 0.40, and more preferably 0.41 and 0.42.

Ti ⁴⁺ tends to lower the meltability of the glass and increase the liquidus temperature. On the other hand, Nb ⁵⁺ suppresses a decrease in liquidus temperature and an increase in refractive index, and contributes to high dispersion. Therefore, by including Nb ⁵⁺ at a fixed ratio to Ti ⁴⁺ , it is possible to suppress a decrease in glass meltability and an increase in liquidus temperature. Therefore, in the optical glass according to the present embodiment, the cation ratio [Ti ⁴⁺ / Nb ⁵⁺ ] is preferably in the above range.

The optical glass according to the first embodiment is a phosphate optical glass. The phosphate optical glass refers to an optical glass mainly containing a phosphate as a glass network forming component. Therefore, the optical glass according to Embodiment 1-1 includes a phosphate as a network-forming component, and its content is expressed as the content of P ₂ O ₅ . P ₂ O ₅ , Al ₂ O ₃ , B ₂ O ₃ , SiO _{2 and the} like are known as glass network forming components. Here, the phrase “mainly containing a phosphate as a glass network-forming component” means that the content of P ₂ O ₅ in mass% is higher than the content of any of Al ₂ O ₃ , B ₂ O ₃ , and SiO _2. Also means a lot of glass.

In the optical glass according to Embodiment 1-1, the lower limit of the content of P ₂ O ₅ is preferably 7.0%, and further, 8.0%, 9.0%, 10.0%, 11.0%, 12.0%, 12.5%, and 13.0% are more preferable. The upper limit of the content of P ₂ O ₅ is preferably 35.0%, and more preferably 34.5%, 34.0%, 33.5%, and 33.0%.

P ₂ O ₅ is an essential component for suppressing an increase in the refractive index nd and for containing a large amount of highly dispersed components in the glass. On the other hand, if P ₂ O ₅ is excessively contained, the meltability deteriorates. Therefore, in the optical glass according to the present embodiment, the content of P ₂ O ₅ is preferably in the above range.

In addition, in the optical glass according to Embodiment 1-1, when the content of the glass component is represented by cation%, the upper limit of the content of P ⁵⁺ is preferably 45.00 cation%, and more preferably 44.00 cation%. 50 cation%, 44.00 cation%, 43.50 cation%, 43.00 cation%, 42.50 cation%, 42.00 cation%, 41.50 cation%, 41.00 cation%, 40.50 cation %, 40.00 cation%, 39.50 cation%, 39.00 cation%, 38.50 cation%. The lower limit of the P ⁵⁺ content is preferably 20.00 cation%, more preferably 20.50 cation%, 21.00 cation%, 21.50 cation%, 22.00 cation%, 22.50 cation% %, 23.00 cation%, 23.50 cation%, 24.00 cation%, 24.50 cation%, 25.00 cation%, and 25.50 cation% in this order.

P ⁵⁺ is an essential component for suppressing an increase in the refractive index nd and for containing a large amount of highly dispersed components in glass. On the other hand, when P ⁵⁺ is excessively contained, the meltability deteriorates. Therefore, in the optical glass according to the present embodiment, the content of P ⁵⁺ is preferably in the above range.

In the optical glass according to Embodiment 1-1, the upper limit of the content of Bi ₂ O ₃ is preferably 29.0%, and furthermore, 28.5%, 28.0%, 27.5%, 27.0%, 25.0%, 20.0%, 15.0%, 10.0%, 6.0%, and 5.0% are more preferable. The lower limit of the content of Bi ₂ O ₃ is preferably 0%. The content of Bi ₂ O ₃ may be 0%.

Bi ₂ O ₃ has a function of improving the thermal stability of glass by containing an appropriate amount. On the other hand, when the content of Bi ₂ O ₃ is increased, the refractive index is increased, and the coloring of the glass is increased. Therefore, the content of Bi ₂ O ₃ is preferably set in the above range.

In the optical glass according to Embodiment 1-1, when the content of the glass component is represented by cation%, the upper limit of the Bi ³⁺ content is preferably 20.00 cation%, and more preferably 19. 50 cation%, 19.00 cation%, 18.50 cation%, 18.00 cation%, 17.50 cation%, 17.00 cation%, and 16.50 cation% are more preferable in this order. The lower limit of the Bi ³⁺ content is preferably 3.00 cation%, and more preferably 1.50 cation%, 1.00 cation%, and 0.40 cation%. The content of Bi ³⁺ may be 0 cation%.

Bi ³⁺ has a function of improving the thermal stability of glass by containing an appropriate amount. On the other hand, when the content of Bi ³⁺ is increased, the refractive index increases, and the coloring of the glass increases. Therefore, the content of Bi ³⁺ is preferably in the above range.

In the optical glass according to Embodiment 1-1, the lower limit of the mass ratio of the total content of TiO ₂ and WO _{3 to} the content of Nb ₂ O ₅ [(TiO ₂ + WO ₃ ) / Nb ₂ O ₅ ] is as follows: It is preferably 0.15, and more preferably 0.17, 0.19, 0.20, 0.21, 0.23, 0.25, 0.26, 0.28, 0.30, 0.35. , 0.40, 0.45, 0.50, 0.55, 0.56, 0.57, 0.58, 0.59, 0.60, 0.61, 0.62, 0.63, 0 .64, then 0.65. The upper limit of the mass ratio [(TiO ₂ + WO ₃ ) / Nb ₂ O ₅ ] is preferably 8.00, and 7.90, 7.80, 7.70, 7.60, and 7. 40, 7.20, and 7.00 are more preferable.

By setting the value of the mass ratio [(TiO ₂ + WO ₃ ) / Nb ₂ O ₅ ] in the above range, it is possible to obtain a glass having high dispersion suitable for chromatic aberration correction while suppressing an increase in the refractive index.

In the optical glass according to Embodiment 1-1, when the content of the glass component is represented by cation%, the cation ratio of the total content of Ti ⁴⁺ and W ^{6+ and} the content of Nb ⁵⁺ [( Ti ⁴⁺ + W ⁶⁺ ) / Nb ⁵⁺ ] is preferably 7.70, more preferably 7.60, 7.50, 7.40, 7.35, 7.30, 7.28, 7.26 is more preferred. The lower limit of the cation ratio [(Ti ⁴⁺ + W ⁶⁺ ) / Nb ⁵⁺ ] is preferably 0.40, and more preferably 0.41 and 0.42.

By setting the value of the cation ratio [(Ti ⁴⁺ + W ⁶⁺ ) / Nb ⁵⁺ ] in the above range, it is possible to obtain a glass having high dispersion suitable for correcting chromatic aberration while suppressing an increase in the refractive index. it can.

In the optical glass according to Embodiment 1-1, the mass of the total content of TiO ₂ , Nb ₂ O _5, and WO _{3 and} the total content of TiO ₂ , Nb ₂ O ₅ , WO _3, and Bi ₂ O ₃ the lower limit of the ratio _{[(TiO 2 + Nb 2 O} 5 + WO 3) / (TiO 2 + Nb 2 O 5 + WO 3 + Bi 2 O 3)] is preferably 0.45, more, 0.50,0.55 , 0.60, 0.65, 0.70, 0.75, 0.80, 0.85. The upper limit of the mass ratio [(TiO ₂ + Nb ₂ O ₅ + WO ₃ ) / (TiO ₂ + Nb ₂ O ₅ + WO ₃ + Bi ₂ O ₃ )] is preferably 1.00. The content of Bi ₂ O ₃ may be 0%.

The mass ratio _{[(TiO 2 + Nb 2 O} 5 + WO 3) / (TiO 2 + Nb 2 O 5 + WO 3 + Bi 2 O 3)]
By setting the value in the above range, the deterioration of the transmittance can be suppressed, and the increase in the refractive index and the increase in the specific gravity can be suppressed.

In the optical glass according to Embodiment 1-1, the lower limit of the total content of TiO ₂ , Nb ₂ O _5, and WO ₃ [TiO ₂ + Nb ₂ O ₅ + WO ₃ ] is preferably 43.0%, and Is more preferably in the order of 45.0%, 46.0%, 47.0%, 48.0%, 49.0%, 50.0%, 52.0%. Further, the upper limit of the total content [TiO ₂ + Nb ₂ O ₅ + WO ₃ ] is preferably 85.0%, further 84.0%, 83.0%, 82.0%, 81.0%. , 79.0%, and 77.0% are more preferable.

TiO ₂ , Nb ₂ O ₅ and WO ₃ are all glass components that contribute to high dispersion, but also cause an increase in coloring. Therefore, the total content [TiO ₂ + Nb ₂ O ₅ + WO ₃ ] is preferably in the above range.

In the optical glass according to the first embodiment, when the content of the glass component is represented by cation% and the content of W ⁶⁺ exceeds 0 cation%, the content of Ba ²⁺ and W The upper limit of the cation ratio [Ba ²⁺ / W ⁶⁺ ] with respect to the content of ⁶⁺ is preferably 0.14, and further in the order of 0.13, 0.12, 0.11, and 0.10. preferable.

Ba ²⁺ is a component that contributes to low dispersion. Therefore, in the optical glass according to Embodiment 1-1, the desired high dispersibility is obtained by ^{incorporating} W ⁶⁺ , which is a high dispersing component, to the above cation ratio with respect to the content of Ba ²⁺ . Can be maintained.

In the optical glass according to Embodiment 1-1, when the content of the glass component is represented by cation%, the content of W ⁶⁺ is 0 cation%, and the content of Ba ²⁺ is 0 cation. When it exceeds cation%, the upper limit of the total content of Ti ⁴⁺ and Bi ³⁺ [Ti ⁴⁺ + Bi ³⁺ ] is preferably 35.00 cation%, more preferably 34.00 cation%, 33 0.000%, 32.50%, 32.30%, 32.00%, 31.80%, 31.60%, 31.40%, 31.20%, 31.00% Cation%, 30.80 cation%, 30.60 cation%, 30.40 cation%, 30.20 cation%, 30.10 cation%, 30.00 cation% are more preferable in this order. The lower limit of the total content [Ti ⁴⁺ + Bi ³⁺ ] is preferably 21.00 cation%, more preferably 21.20 cation%, 21.40 cation%, 21.60 cation%, and 21.80 cation%. 2,2.00 cation%, 22.20 cation%, 22.40 cation%, 22.60 cation%, 22.80 cation%, 23.00 cation%, 23.10 cation%, 23.20 cation%, 23 More preferably, in the order of .30 cation%, 23.40 cation%, and 23.50 cation%.

When the content of W ⁶⁺ is 0 cation% and the content of Ba ²⁺ exceeds 0 cation%, Ti has the largest contribution to high dispersion after W ⁶⁺ among the high dispersion components. ^By setting the total content of ⁴⁺ and Bi ³⁺ having the function of improving thermal stability in the above range, it is possible to suppress the low dispersion by Ba ²⁺ .

(Glass component)
The optical glass according to Embodiment 1-1 can include the following glass components.

The optical glass according to Embodiment 1-1 can include B ₂ O ₃ , SiO ₂ , and Al ₂ O ₃ as network forming components of the glass other than P ₂ O ₅ .

In the optical glass according to Embodiment 1-1, the upper limit of the content of B ₂ O ₃ is preferably 4.0%, and more preferably 3.0%, 2.0%, and 1.0%. More preferred in order. The content of B ₂ O ₃ may be 0%.

B ₂ O ₃ is a network-forming component of glass, and has a function of improving the meltability of glass and suppressing an increase in the refractive index. On the other hand, when the content of B ₂ O ₃ is large, a decrease in Abbe number is suppressed to prevent high dispersion, and the chemical durability tends to decrease. Therefore, the upper limit of the B ₂ O ₃ content is preferably in the above range from the viewpoint of improving the thermal stability, meltability, moldability, and the like of the glass while suppressing an increase in the refractive index. On the other hand, the lower limit of the content of B ₂ O ₃ is preferably within the above range, from the viewpoint of maintaining the desired chemical resistance while obtaining a desired Abbe number.

In the optical glass according to Embodiment 1-1, the upper limit of the content of SiO ₂ is preferably 8.0%, and further, 7.0%, 6.0%, 5.5%, and 5.5%. 0%, 4.5%, 4.0%, 3.5%, and 3.0% are more preferable. The content of SiO ₂ may be 0%.

SiO ₂ is a glass network forming component and has a function of improving the thermal stability, chemical durability, and weather resistance of the glass, increasing the viscosity of the molten glass, and facilitating the molding of the molten glass. On the other hand, when the content of SiO ₂ is large, the melting property and the low-temperature softening property of the glass are reduced, and the glass material tends to remain unmelted. Therefore, the upper limit of the content of SiO ₂ is preferably in the above range from the viewpoint of improving the melting property, low-temperature softening property, and the like of the glass.

In the optical glass according to Embodiment 1-1, the upper limit of the content of Al ₂ O ₃ is preferably 5.0%, and more preferably 4.0%, 3.5%, 2.5%, 2.0%, 1.5%, 1.0%, and 0.5% are more preferable. The content of Al ₂ O ₃ may be 0%.

Al ₂ O ₃ is a glass component having a function of suppressing an increase in the refractive index and improving the chemical durability and weather resistance of the glass, and can be considered as a network forming component. On the other hand, when the content of Al ₂ O ₃ is increased, problems such as a decrease in the thermal stability of the glass, an increase in the glass transition temperature Tg, and a decrease in the meltability are likely to occur. From the viewpoint of avoiding such a problem, the upper limit of the content of Al ₂ O ₃ is preferably within the above range.

In the optical glass according to Embodiment 1-1, the total content of P ₂ O ₅ , B ₂ O ₃ , SiO _2, and Al ₂ O ₃ that are network forming components of the glass [P ₂ O ₅ + B ₂ O ₃ + SiO _{2] 2} + Al ₂ O ₃ ] is preferably 45.0%, more preferably 43.0%, 41.0%, 39.0%, 37.0%, 35.0%, 33.0%. % Is more preferable. The lower limit of the total content [P ₂ O ₅ + B ₂ O ₃ + SiO ₂ + Al ₂ O ₃ ] is preferably 10.0%, further 11.0%, 12.0% and 12.5%. %, 13.0%, 14.0%, and 15.0% are more preferable.

The upper limit of the total content _{[P 2 O 5 + B 2} O 3 + SiO 2 + Al 2 O 3] is within the above range, it becomes easy to refractive index was maintained within a desired range. By setting the lower limit of the total content [P ₂ O ₅ + B ₂ O ₃ + SiO ₂ + Al ₂ O ₃ ] to the above range, the thermal stability of the glass is improved, and the devitrification of the glass is further suppressed. It will be easier.

Further, in the optical glass according to Embodiment 1-1, the mass ratio of the content of P ₂ O ₅ to the total content of P ₂ O ₅ , B ₂ O ₃ , SiO ₂ and Al ₂ O ₃ [P ₂ O ₅ / lower limit _{(P 2 O 5 + B 2} O 3 + SiO 2 + Al 2 O 3)] is preferably 0.70, more, of 0.75,0.80,0.85,0.90 More preferred in order. The mass ratio [P ₂ O ₅ / (P ₂ O ₅ + B ₂ O ₃ + SiO ₂ + Al ₂ O ₃ )] can be set to 1.00.

When the mass ratio [P ₂ O ₅ / (P ₂ O ₅ + B ₂ O ₃ + SiO ₂ + Al ₂ O ₃ )] is small, the thermal stability of the glass is lowered and the meltability is also lowered. Therefore, the lower limit of the mass ratio [P ₂ O ₅ / (P ₂ O ₅ + B ₂ O ₃ + SiO ₂ + Al ₂ O ₃ )] is in the above range from the viewpoint of maintaining high dispersion and good melting property of the glass. Preferably, there is.

In the optical glass according to Embodiment 1-1, the lower limit of the content of TiO ₂ is preferably 1.0%, and further, 3.0%, 5.0%, 6.0%, and 7.0. 0%, 8.0%, 9.0%, 10.0% are more preferable. The upper limit of the content of TiO ₂ is preferably 45.0%, and more preferably 44.0%, 43.0%, 42.0%, 41.0%, 40.0%, 39. The order of 0% is more preferable.

TiO ₂ suppresses an increase in the refractive index as compared with Nb ₂ O ₅ and Bi ₂ O _3, and greatly contributes to high dispersion. On the other hand, TiO ₂ relatively easily increases the coloring of glass. Further, TiO ₂ promotes crystal formation in the glass in the process of forming and gradually cooling the molten glass to obtain the optical glass, and lowers the transparency (white turbidity) of the glass. Therefore, in the optical glass according to the present embodiment, the content of TiO ₂ is preferably in the above range.

In the optical glass according to Embodiment 1-1, when the content of the glass component is represented by cation%, the upper limit of the Ti ⁴⁺ content is preferably 48.00 cation%, and more preferably 47.00 cation%. 00 cation%, 46.00 cation%, 45.50 cation%, 45.00 cation%, 44.50 cation%, 44.00 cation%, 43.50 cation%, 43.00 cation%, 42.50 cation %, 42.00 cation%. The lower limit of the content of Ti ⁴⁺ is preferably 10.00 cation%, more preferably 11.00 cation%, 11.50 cation%, 12.00 cation%, 12.50 cation%, 13.00 cation%. %, 13.50 cation%, 14.00 cation%, 14.50 cation%, 15.00 cation%, and 15.50 cation% in this order.

Ti ⁴⁺ suppresses an increase in the refractive index as compared with Nb ⁵⁺ and Bi ^3+, and greatly contributes to high dispersion. On the other hand, Ti ⁴⁺ relatively easily increases the coloring of glass. Further, Ti ⁴⁺ promotes crystal formation in the glass in the process of forming and gradually cooling the molten glass to obtain the optical glass, and lowers the transparency (white turbidity) of the glass. Therefore, in the optical glass according to the present embodiment, the content of Ti ⁴⁺ is preferably in the above range.

In the optical glass according to Embodiment 1-1, the upper limit of the mass ratio [TiO ₂ / P ₂ O ₅ ] between the content of TiO _{2 and} the content of P ₂ O ₅ is preferably 4.50, More preferably, the order is 4.00, 3.50, 3.00, 2.50, 2.00, 1.50. The lower limit of the mass ratio [TiO ₂ / P ₂ O ₅ ] is preferably 0.04, and more preferably 0.08, 0.12, 0.16, 0.20, 0.24,. 28, 0.32, 0.36, 0.40, 0.44, 0.48, and 0.52 are more preferable.

In the optical glass according to the first embodiment, the inclusion of TiO ₂ promotes crystal formation in the glass, causing a problem that the transparency of the glass is reduced (white turbidity). This problem can be solved by adding P ₂ O ₅ , which is a network-forming component, to TiO _{2 at} a ratio in the above range.

In the optical glass according to Embodiment 1-1, when the content of the glass component is represented by cation%, the cation ratio [Ti ⁴⁺ / P ⁵ ] between the content of Ti ^{4+ and} the content of P ^{5+. +} ] Is preferably 1.50, more preferably 1.40, 1.30, 1.29, 1.28, 1.27, 1.26, 1.25, 1.25,. 23 and 1.22 are more preferable. The lower limit of the cation ratio [Ti ⁴⁺ / P ⁵⁺ ] is preferably 0.50, and more preferably 0.51, 0.52, and 0.53.

In the optical glass according to Embodiment 1-1, by including Ti ⁴⁺ , the generation of crystals in the glass is promoted, and a problem occurs in that the transparency of the glass is reduced (white turbidity). This problem can be solved by adding P ⁵⁺ , which is a network-forming component, to Ti ^{4+ in} a proportion within the above range.

In the optical glass according to Embodiment 1-1, the lower limit of the content of Nb ₂ O ₅ is preferably 5.5%, and further, 6.0%, 6.5%, 7.0%, 7.5%, 8.0%, and 8.5% are more preferable. The upper limit of the content of Nb ₂ O ₅ is preferably 55.0%, and more preferably 54.0%, 53.0%, 52.0%, 51.0%, 50.0%, It is more preferable in the order of 49.0% and 48.0%.

Nb ₂ O ₅ is a component that contributes to high dispersion. It is also a glass component that improves the thermal stability and chemical durability of the glass. On the other hand, when the content of Nb ₂ O ₅ is too large, the thermal stability of the glass tends to decrease, and the coloring of the glass tends to increase. Therefore, in the optical glass according to the present embodiment, the content of Nb ₂ O ₅ is preferably in the above range.

In the optical glass according to Embodiment 1-1, when the content of the glass component is represented by cation%, the upper limit of the Nb ⁵⁺ content is preferably 45.00 cation%, and more preferably 44.00 cation%. 00 cation%, 43.50 cation%, 43.00 cation%, 42.50 cation%, 42.00 cation%, 41.50 cation%, 41.00 cation%, 40.50 cation%, 40.00 cation %, 39.50 cation%, 39.00 cation%, and 38.50 cation% in this order. The lower limit of the Nb ⁵⁺ content is preferably 1.00 cation%, more preferably 2.00 cation%, 2.50 cation%, 3.00 cation%, 3.50 cation%, 4.00 cation% %, 4.50 cation%, 5.00 cation%, 5.50 cation%, 6.00 cation%, and 6.50 cation% in this order.

Nb ⁵⁺ is a component that contributes to high dispersion. It is also a glass component that improves the thermal stability and chemical durability of the glass. On the other hand, if the content of Nb ⁵⁺ is too large, the thermal stability of the glass tends to decrease, and the coloring of the glass tends to increase. Therefore, in the optical glass according to the present embodiment, the content of Nb ⁵⁺ is preferably in the above range.

In the optical glass according to Embodiment 1-1, the upper limit of the content of WO ₃ is preferably 45.0%, further 44.5%, 44.0%, 43.5%, and 43.5%. 0%, 42.0%, 41.0%, and 40.0% are more preferable. In addition, the lower limit of the content of WO ₃ is preferably 9.0%, and more preferably 7.0%, 5.0%, 3.0%, 1.0%, 0.5%, and 0.5%. 3% and 0.1% are more preferable. The content of WO ₃ may be 0%.

WO ₃ suppresses an increase in the refractive index and greatly contributes to high dispersion. However, compared to TiO ₂ , Nb ₂ O ₅ and Bi ₂ O ₃ , WO ₃ is more likely to cause coloring of the glass and deteriorates the transmittance. Therefore, the content of WO ₃ is preferably in the above range.

In the optical glass according to Embodiment 1-1, when the content of the glass component is represented by cation%, the upper limit of the content of W ⁶⁺ is preferably 30.00 cation%, and more preferably 29. 00 cation%, 28.50 cation%, 28.00 cation%, 27.50 cation%, 27.00 cation%, 26.50 cation%, 26.00 cation%, 25.50 cation%, 25.00 cation % And 24.50 cation% in this order. The lower limit of the content of W ⁶⁺ is preferably 0.40 cation%, more preferably 0.20 cation%, and then 0.10 cation%. The content of W ⁶⁺ may be 0 cation%.

W ⁶⁺ suppresses an increase in the refractive index and greatly contributes to high dispersion. However, compared to Ti ⁴⁺ , Nb ^5+, and Bi ³⁺ , W ⁶⁺ tends to cause coloring of the glass and deteriorates the transmittance. Therefore, the content of W ⁶⁺ is preferably in the above range.

In the optical glass according to Embodiment 1-1, the upper limit of the total content of TiO ₂ , Nb ₂ O ₅ , WO ₃ and Bi ₂ O ₃ [TiO ₂ + Nb ₂ O ₅ + WO ₃ + Bi ₂ O ₃ ] is preferably set. Is 86.0%, and more preferably 85.5%, 85.0%, 84.5%, 84.0%, 83.5%, 83.0%. The lower limit of the total content [TiO ₂ + Nb ₂ O ₅ + WO ₃ + Bi ₂ O ₃ ] is preferably 55.0%, and further 55.5%, 56.0%, 56.5%, 57.0%, 57.5%, 58.0%, 58.5%, 59.0%, 59.5%, 60.0%, 60.5%, 61.0%, 61.5%, 62.0%, 62.5%, 63.0%, 63.5%, and 64.0% are more preferable.

TiO ₂ , Nb ₂ O ₅ , WO ₃ and Bi ₂ O ₃ contribute to high dispersion of glass. Also, by containing an appropriate amount, it also has a function of improving the thermal stability of the glass. However, Bi ₂ O ₃ has a stronger function of increasing the refractive index than TiO ₂ , Nb ₂ O ₅ and WO ₃ . Therefore, the upper limit of the total content [TiO ₂ + Nb ₂ O ₅ + WO ₃ + Bi ₂ O ₃ ] is preferably in the above range from the viewpoint of suppressing the increase in the refractive index and the increase in the coloring of the glass. From the viewpoint of increasing the dispersion of the glass and improving the thermal stability of the glass, the lower limit of the total content [TiO ₂ + Nb ₂ O ₅ + WO ₃ + Bi ₂ O ₃ ] is preferably within the above range.

In the optical glass according to Embodiment 1-1, when the content of the glass component is represented by cation%, the total content of Ti ⁴⁺ , Nb ⁵⁺ , W ⁶⁺ and Bi ³⁺ [Ti ⁴⁺ + Nb ⁵⁺ + W ⁶⁺ + Bi ³⁺ ] is preferably 75.00 cation%, more preferably 74.50 cation%, 74.00 cation%, 73.50 cation%, 73.00 cation%, 72 .50 cation%, 72.00 cation%, 71.50 cation%, 71.00 cation%, and 70.50 cation% are more preferable in this order. The lower limit of the total content [Ti ⁴⁺ + Nb ⁵⁺ + W ⁶⁺ + Bi ³⁺ ] is preferably 52.00 cation%, more preferably 52.10 cation%, 52.15 cation%, and 52.20 cation%. , 52.25 cation%, and 52.30 cation%.

In the optical glass according to Embodiment 1-1, Ti ⁴⁺ , Nb ⁵⁺ , W ^6+, and Bi ³⁺ contribute to high dispersion of the glass. Also, by containing an appropriate amount, it also has a function of improving the thermal stability of the glass. Therefore, the lower limit of the total content [Ti ⁴⁺ + Nb ⁵⁺ + W ⁶⁺ + Bi ³⁺ ] is preferably in the above range. On the other hand, Ti ⁴⁺ , Nb ⁵⁺ , W ⁶⁺ and Bi ³⁺ increase the coloring of the glass. Therefore, the upper limit of the total content [Ti ⁴⁺ + Nb ⁵⁺ + W ⁶⁺ + Bi ³⁺ ] is preferably within the above range.

In the optical glass according to Embodiment 1-1, the upper limit of the content of Li ₂ O is preferably 1.2%, and further, 1.1%, 1.0%, 0.8%, and 0%. It is more preferable in the order of 0.6% and 0.4%. The content of Li ₂ O may be 0%.

Li ₂ O functions to suppress an increase in the refractive index and improve the meltability of the glass. Therefore, the content of Li ₂ O is preferably in the above range from the viewpoint of securing the meltability while maintaining the required optical characteristics.

In the optical glass according to Embodiment 1-1, the upper limit of the content of Na ₂ O is preferably 6.0%, and further, 5.0%, 4.5%, 4.0%, and 3%. It is more preferable in the order of 0.5% and 3.0%. Further, the lower limit of the content of Na ₂ O is preferably 0%. The content of Na ₂ O may be 0%.

In the optical glass according to Embodiment 1-1, the upper limit of the content of K ₂ O is preferably 12.0%, further 11.0%, 10.0%, 9.0%, 8%. It is more preferred in the order of 0.5% and 8.0%. Further, the lower limit of the content of K ₂ O is preferably 0.1% in order to maintain good thermal stability of the glass and to suppress an increase in the liquidus temperature, and more preferably 0.3%. , 0.5%, 1.0%, 1.5%, 2.0%, 2.5%. The content of K ₂ O may be 0%.

Both Na ₂ O and K ₂ O have a function of suppressing an increase in the refractive index and improving the meltability of the glass. However, when their contents are increased, the thermal stability and the chemical durability of the glass become higher. Properties and weather resistance decrease. Therefore, it is preferable that each content of Na ₂ O and K ₂ O be in the above range.

In the optical glass according to Embodiment 1-1, the upper limit of the total content of Li ₂ O, Na ₂ O, and K ₂ O [Li ₂ O + Na ₂ O + K ₂ O] is preferably 15.0%, and further, Is more preferred in the order of 14.0%, 13.0%, 12.0%, 11.0%, 10.0%, 9.0%. The lower limit of the total content [Li ₂ O + Na ₂ O + K ₂ O] is preferably 0.1% in order to maintain good thermal stability of the glass and suppress a rise in liquidus temperature. Is more preferably in the order of 0.3%, 0.5%, 1.0%, 1.5%, 2.0%, 2.5%. The total content [Li ₂ O + Na ₂ O + K ₂ O] may be 0%.

Li ₂ O, Na ₂ O and K ₂ O all have a function of suppressing an increase in the refractive index and improving the meltability of the glass. However, when these contents increase, the thermal stability, chemical durability and weather resistance of the glass decrease. Therefore, the total content of Li ₂ O, Na ₂ O and K ₂ O [Li ₂ O + Na ₂ O + K ₂ O] is preferably in the above range.

In the optical glass according to Embodiment 1-1, the upper limit of the content of Rb ₂ O is preferably 2.0%, and further, in the order of 1.0%, 0.5%, and 0.1%. Is more preferable. Further, the lower limit of the content of Rb ₂ O is preferably 0%. The content of Rb ₂ O may be 0%.

In the optical glass according to Embodiment 1-1, the upper limit of the content of Cs ₂ O is preferably 6.0%, and further, 5.0%, 4.5%, 4.0%, and 3%. More preferred in the order of .5%. Further, the lower limit of the content of Cs ₂ O is preferably 0%. The content of Cs ₂ O may be 0%.

Both Rb ₂ O and Cs ₂ O have a function of suppressing an increase in the refractive index and improving the melting property of the glass. However, when the content of these elements is increased, the thermal stability and the chemical durability of the glass are reduced. Properties and weather resistance decrease. Therefore, it is preferable that each content of Rb ₂ O and Cs ₂ O be in the above range.

  In the optical glass according to Embodiment 1-1, the upper limit of the content of MgO is preferably 5.0%, and further, 4.0%, 3.0%, 2.0%, and 1.0%. % Is more preferable. Further, the lower limit of the content of MgO is preferably 0%. The content of MgO may be 0%.

  In the optical glass according to Embodiment 1-1, the upper limit of the content of CaO is preferably 5.0%, and further, 4.0%, 3.0%, 2.0%, and 1.0%. % Is more preferable. The lower limit of the CaO content is preferably 0%. The content of CaO may be 0%.

  In the optical glass according to Embodiment 1-1, the upper limit of the content of SrO is preferably 6.0%, and further, 5.8%, 5.7%, 5.6%, 5.5. %, 5.0%, 4.5%, 4.0%, 3.5%, 3.0%, and 2.5%. The lower limit of the content of SrO is preferably 0%. The content of SrO may be 0%.

  In the optical glass according to Embodiment 1-1, the upper limit of the BaO content is preferably 6.0%, and further, 5.8%, 5.7%, 5.6%, 5.5. %, 5.0%, 4.5%, and 4.0%. Further, the lower limit of the content of BaO is preferably 0%. The content of BaO may be 0%.

  MgO, CaO, SrO, and BaO are all glass components that have the function of improving the thermal stability and fusibility of glass. However, when the content of these glass components is increased, the high dispersibility is impaired, the thermal stability of the glass is reduced, and the glass is easily devitrified. Therefore, the content of each of these glass components is preferably within the above range.

In addition, in the optical glass according to Embodiment 1-1, when the content of the glass component is represented by cation%, the upper limit of the content of Ba ²⁺ is preferably 13.00 cation%, and further 12.1. 00 cation%, 11.00 cation%, 10.00 cation%, 9.00 cation%, 8.00 cation%, 7.50 cation%, 7.00 cation%, 6.50 cation%, 6.00 cation %, 5.50 cation%, 5.00 cation%, 4.50 cation%, 4.00 cation%, and 3.50 cation% in this order. Further, the lower limit of the content of Ba ²⁺ is preferably 0 cation%. The content of Ba ²⁺ may be 0 cation%.

Mg ²⁺ , Ca ²⁺ , Sr ²⁺ , and Ba ²⁺ are all glass components that have the function of improving the thermal stability and meltability of the glass. However, when the content of these glass components is increased, the high dispersibility is impaired, the thermal stability of the glass is reduced, and the glass is easily devitrified. Therefore, the content of each of these glass components is preferably within the above range.

  In the optical glass according to Embodiment 1-1, the upper limit of the total content of MgO, CaO, SrO, and BaO [MgO + CaO + SrO + BaO] is preferably 10 from the viewpoint of maintaining thermal stability without hindering high dispersion. 0.0%, and more preferably 9.0%, 8.0%, 7.0%, 6.0%, 5.5%, and 5.0%. The lower limit of the total content [MgO + CaO + SrO + BaO] is preferably 0%. The total content [MgO + CaO + SrO + BaO] may be 0%.

  In the optical glass according to Embodiment 1-1, the upper limit of the content of ZnO is preferably 5.0%, and further, 4.0%, 3.0%, 2.0%, and 1.0%. % Is more preferable. The lower limit of the content of ZnO is preferably 0%. The content of ZnO may be 0%.

  ZnO is a glass component having a function of accelerating the melting of glass raw materials when melting glass (that is, a function of improving melting property). Further, ZnO has a stronger effect of improving the thermal stability of glass and lowering the liquidus temperature than other divalent metal components such as alkaline earth metals. Therefore, from the viewpoint of improving the meltability and thermal stability of the glass, the lower limit of the ZnO content is preferably within the above range. In addition, from the viewpoint of suppressing the low dispersion of glass, the upper limit of the ZnO content is preferably within the above range.

In the optical glass according to Embodiment 1-1, the upper limit of the content of ZrO ₂ is preferably 6.0%, and further, 5.0%, 4.5%, 4.0%, and 3.0%. 0% and 2.0% are more preferable. Further, the lower limit of the content of ZrO ₂ is preferably 0%. The content of ZrO ₂ may be 0%.

ZrO ₂ is a glass component having a function of improving the thermal stability of glass. However, when the content of ZrO ₂ is too large, the refractive index increases, and the thermal stability of the glass tends to decrease. In addition, the glass material is likely to remain undissolved. Therefore, the upper limit of the ZrO ₂ content is preferably in the above range from the viewpoint of maintaining the melting property and thermal stability of the glass satisfactorily and achieving the required optical characteristics. On the other hand, the lower limit of the ZrO ₂ content is preferably in the above range from the viewpoint of improving the thermal stability of the glass while achieving the required optical characteristics.

In the optical glass according to Embodiment 1-1, the upper limit of the content of Ta ₂ O ₅ is preferably 9.0%, and further, 8.0%, 7.0%, 6.0%, 5.0%, 4.0%, and 3.0% are more preferable. Further, the lower limit of the content of Ta ₂ O ₅ is preferably 0%. The content of Ta ₂ O ₅ may be 0%.

Ta ₂ O ₅ is a glass component having a function of improving the thermal stability of glass. On the other hand, Ta ₂ O ₅ increases the refractive index and lowers the glass dispersion. Further, Ta ₂ O ₅ is an extremely expensive component as compared with other glass components. As the content of Ta ₂ O ₅ increases, the production cost of glass increases. Furthermore, since Ta ₂ O ₅ has a higher molecular weight than other glass components, it increases the specific gravity of glass, and consequently increases the weight of the glass optical element. Further, when the content of Ta ₂ O ₅ is increased, the melting property of the glass is reduced, and when the glass is melted, the glass material tends to be left unmelted. Therefore, the content of Ta ₂ O ₅ is preferably in the above range.

In the optical glass according to Embodiment 1-1, the upper limit of the content of Ga ₂ O ₃ is preferably 4.0%, and further, 3.5%, 3.0%, 2.5%, 2.0%, 1.5%, 1.0%, 0.5%, and 0.1% are more preferable. The lower limit of the content of Ga ₂ O ₃ is preferably 0%. The content of Ga ₂ O ₃ may be 0%.

In the optical glass according to Embodiment 1-1, the upper limit of the content of In ₂ O ₃ is preferably 5.0%, more preferably 4.5%, 4.0%, 3.5%, It is more preferable in the order of 3.0%. Further, the lower limit of the content of In ₂ O ₃ is preferably 0%. The content of In ₂ O ₃ may be 0%.

In the optical glass according to Embodiment 1-1, the upper limit of the content of Sc ₂ O ₃ is preferably 5.0%, and more preferably 4.0%, 3.0%, 2.0%, The order of 1.0% is more preferable. The lower limit of the content of Sc ₂ O ₃ is preferably 0%. The content of Sc ₂ O ₃ may be 0%.

In the optical glass according to Embodiment 1-1, the upper limit of the content of HfO ₂ is preferably 8.0%, and further, 7.0%, 6.5%, 6.0%, and 5.0%. 5%, 5.0%, 4.5%, 4.0%, 3.5%, 3.0%, 2.5%, 2.0%, 1.5%, 1.0%, 0.1% It is more preferable in the order of 5% and 0.1%. Further, the lower limit of the content of HfO ₂ is preferably 0%. The content of HfO ₂ may be 0%.

Ga ₂ O ₃ , In ₂ O ₃ , Sc ₂ O ₃ , and HfO ₂ all have a function of increasing the refractive index nd and are expensive components. Therefore, it is preferable that each content of Ga ₂ O ₃ , In ₂ O ₃ , Sc ₂ O ₃ , and HfO ₂ is in the above range.

In the optical glass according to Embodiment 1-1, the upper limit of the content of Lu ₂ O ₃ is preferably 5.0%, and more preferably 4.5%, 4.0%, 3.5%, The order of 3.0% is more preferable. Further, the lower limit of the content of Lu ₂ O ₃ is preferably 0%. The content of Lu ₂ O ₃ may be 0%.

Lu ₂ O ₃ has a function of increasing the refractive index nd. In addition, since it has a large molecular weight, it is also a glass component that increases the specific gravity of glass. Therefore, it is preferable to reduce the content of Lu ₂ O _3, it is preferable that the content of Lu ₂ O ₃ is within the above range.

In the optical glass according to Embodiment 1-1, the upper limit of the content of GeO ₂ is preferably 6.0%, and more preferably 5.0%, 4.0%, 3.0%, and 2.0%. 0%, 1.5%, 1.0%, 0.5%, and 0.1% are more preferable in this order. Further, the lower limit of the content of GeO ₂ is preferably 0%. The content of GeO ₂ may be 0%.

GeO ₂ has a function of increasing the refractive index nd, and is a prominent and expensive component among commonly used glass components. Therefore, the content of GeO ₂ is preferably in the above range from the viewpoint of reducing the production cost of glass.

In the optical glass according to Embodiment 1-1, the upper limit of the content of La ₂ O ₃ is preferably 5.0%, and more preferably 4.5%, 4.0%, 3.5%, It is more preferable in the order of 3.0%, 2.5%, 2.0%, 1.5%, 1.0%, and 0.5%. The lower limit of the content of La ₂ O ₃ is preferably 0%. The content of La ₂ O ₃ may be 0%.

When the content of La ₂ O ₃ increases, the thermal stability of the glass decreases, and the glass tends to be devitrified during production. Therefore, the content of La ₂ O ₃ is preferably within the above range from the viewpoint of suppressing a decrease in the thermal stability of the glass.

In the optical glass according to Embodiment 1-1, the upper limit of the content of Gd ₂ O ₃ is preferably 8.0%, and further, 7.0%, 6.0%, 5.0%, It is more preferable in the order of 4.0%, 3.0%, 2.0%, 1.5%, and 1.0%. Further, the lower limit of the content of Gd ₂ O ₃ is preferably 0%. The content of Gd ₂ O ₃ may be 0%.

If the content of Gd ₂ O ₃ is too large, the thermal stability of the glass decreases, and the glass tends to devitrify during production. Further, when the content of Gd ₂ O ₃ is too large, the specific gravity of the glass increases, which is not preferable. Therefore, the content of Gd ₂ O ₃ is preferably in the above range from the viewpoint of suppressing an increase in specific gravity while maintaining good thermal stability of the glass.

In the optical glass according to Embodiment 1-1, the upper limit of the content of Y ₂ O ₃ is preferably 5.0%, and more preferably 4.5%, 4.0%, 3.5%, It is more preferable in the order of 3.0%, 2.5%, and 2.0%. Further, the lower limit of the content of Y ₂ O ₃ is preferably 0%. The content of Y ₂ O ₃ may be 0%.

If the content of Y ₂ O ₃ is too large, the thermal stability of the glass decreases, and the glass tends to be devitrified during production. Therefore, the content of Y ₂ O ₃ is preferably within the above range from the viewpoint of suppressing a decrease in the thermal stability of the glass.

In the optical glass according to Embodiment 1-1, the upper limit of the content of Yb ₂ O ₃ is preferably 5.0%, and more preferably 4.5%, 4.0%, 3.5%, 3.0%, 2.0%, 1.0%, 0.5%, and 0.1% are more preferable in this order. Further, the lower limit of the content of Yb ₂ O ₃ is preferably 0%. The content of Yb ₂ O ₃ may be 0%.

Yb ₂ O ₃ has a higher molecular weight than La ₂ O ₃ , Gd ₂ O ₃ , and Y ₂ O _3, and therefore increases the specific gravity of glass. As the specific gravity of the glass increases, the mass of the optical element increases. For example, when a lens having a large mass is incorporated in an autofocus type imaging lens, the power required for driving the lens during autofocus increases, and the battery is greatly consumed. Therefore, it is desirable to reduce the content of Yb ₂ O ₃ to suppress an increase in the specific gravity of glass.

On the other hand, if the content of Yb ₂ O ₃ is too large, the thermal stability of the glass decreases, and the glass tends to be devitrified during production. From the viewpoint of preventing a decrease in thermal stability of the glass and suppressing an increase in specific gravity, the content of Yb ₂ O ₃ is preferably in the above range.

The optical glass according to the 1-1 embodiment mainly glass components described above, i.e. _{P 2 O 5, B 2 O} 3, SiO 2, Al 2 O 3, TiO 2, Nb 2 O 5, WO 3, Bi 2 O ₃ , Li ₂ O, Na ₂ O, K ₂ O, Rb ₂ O, Cs ₂ O, MgO, CaO, SrO, BaO, ZnO, ZrO ₂ , Ta ₂ O ₅ , Ga ₂ O ₃ , In ₂ O _{3 , Sc 2 O 3, HfO 2} , Lu 2 O 3, GeO 2, La 2 O 3, Gd 2 O 3, Y 2 O 3, and preferably be composed of Yb ₂ O _3, the glass component of the above Is preferably more than 95%, more preferably more than 98%, even more preferably more than 99%, and even more preferably more than 99.5%. .

In the optical glass according to Embodiment 1-1, the upper limit of the content of TeO ₂ is preferably 5.0%, and further, 4.5%, 4.0%, 3.5%, and 3.0%. 0%, 2.5%, 2.0%, 1.5%, 1.0%, 0.5%, and 0.1% are more preferable in this order. Further, the lower limit of the content of TeO ₂ is preferably 0%. The content of TeO ₂ may be 0%.

TeO ₂ is a component that increases the refractive index nd and has toxicity, so it is preferable to reduce the content of TeO ₂ . Therefore, the content of TeO ₂ is preferably in the above range.

  In the optical glass according to Embodiment 1-1, the anion component, that is, the anion component is mainly an oxygen ion, but contains a small amount of a halogen ion, for example, a chloride ion, an iodine ion, a bromine ion, and the like as other anions. be able to.

  Even when a halide is contained as a glass component, it is preferable to keep the content of the halide small so that the ratio (mass ratio) of the oxide in all the glass components does not become 95% by mass or less.

  That is, in the optical glass according to Embodiment 1-1, it is preferable that the content of the oxide in all glass components is more than 95% by mass. Furthermore, the lower limit of the oxide content in all glass components is more preferably 97% by mass, 99% by mass, 99.5% by mass, 99.9% by mass, 99.95% by mass, and 99.99% by mass. The content of the oxide in all the glass components may be 100% by mass. Glass having an oxide content of 100% by mass in all glass components contains substantially no halide.

  In the optical glass according to Embodiment 1-1, the upper limit of the halogen ion content is preferably 4 anion%, and more preferably 3 anion%, 2 anion%, 1 anion%, and 0.5 anion. % Is more preferable. The content of halogen ions may be 0% by anion. The anion% is a mole percentage when the total content of all the anion components contained in the glass is 100%.

  The optical glass according to Embodiment 1-1 is preferably basically composed of the above glass components, but may contain other components as long as the effects of the present invention are not impaired. is there. Further, in the present invention, the inclusion of unavoidable impurities is not excluded.

<Other component composition>
Pb, As, Cd, Tl, Be and Se all have toxicity. Therefore, it is preferable that the optical glass according to Embodiment 1-1 does not contain these elements as glass components.

  U, Th, and Ra are all radioactive elements. Therefore, it is preferable that the optical glass according to Embodiment 1-1 does not contain these elements as glass components.

  V, Cr, Mn, Fe, Co, Ni, Cu, Pr, Nd, Pm, Sm, Eu, Tb, Dy, Ho, Er, and Tm can increase the coloring of glass and be a source of fluorescence. Therefore, it is preferable that the optical glass according to Embodiment 1-1 does not contain these elements as glass components.

_{Sb (Sb 2 O 3),} Sn (SnO 2), Ce (CeO 2) is an element which can be added to any which acts as a fining agent. Among them, Sb (Sb ₂ O ₃ ) is a fining agent having a large fining effect. However, Sb (Sb ₂ O ₃ ) has a strong oxidizing property, and if the addition amount of Sb (Sb ₂ O ₃ ) is increased, the coloration of the glass increases due to light absorption by Sb ions, which is not preferable. Further, when Sb is present in the melt when the glass is melted, the elution of platinum constituting the glass melting crucible into the melt is promoted, and the platinum concentration in the glass increases. When platinum is present as an ion in glass, the coloring of the glass increases due to light absorption. Also, if platinum is present in the glass as a solid, it becomes a light scattering source and degrades the quality of the glass. Sn (SnO ₂ ) and Ce (CeO ₂ ) have a smaller fining effect than Sb (Sb ₂ O ₃ ). When Sn (SnO ₂ ) and Ce (CeO ₂ ) are added in large amounts, the coloring of the glass becomes stronger. Therefore, when adding a fining agent, it is preferable to add Sb (Sb ₂ O ₃ ) while paying attention to the added amount.

The content of Sb ₂ O ₃ is shown as an external value. That is, when the total content of all glass components other than Sb ₂ O ₃ , SnO ₂ and CeO ₂ is 100% by mass, the content of Sb ₂ O ₃ is preferably less than 1% by mass, more preferably 0.1% by mass. It is less than 5% by mass, more preferably less than 0.1% by mass. The content of Sb ₂ O ₃ may be 0% by mass.

The content of SnO ₂ is also shown as an external display. That is, when the total content of all glass components other than SnO ₂ , Sb ₂ O ₃ and CeO ₂ is 100% by mass, the content of SnO ₂ is preferably less than 2% by mass, more preferably less than 1% by mass. , More preferably less than 0.5% by mass, more preferably less than 0.1% by mass. The content of SnO ₂ may be 0% by mass. By controlling the SnO ₂ content within the above range, the clarity of the glass can be improved.

The content of CeO ₂ is also shown on an out-of-box basis. That is, when the total content of all glass components other than CeO ₂ , Sb ₂ O ₃ and SnO ₂ is 100% by mass, the content of CeO ₂ is preferably less than 2% by mass, more preferably less than 1% by mass. , More preferably less than 0.5% by mass, more preferably less than 0.1% by mass. The content of CeO ₂ may be 0% by mass. When the content of CeO ₂ is in the above range, the clarity of the glass can be improved.

(Glass properties)
<Glass transition temperature Tg>
The upper limit of the glass transition temperature Tg of the optical glass according to Embodiment 1-1 is preferably 750 ° C, and more preferably 740 ° C, 730 ° C, 720 ° C, 710 ° C, and 700 ° C. The lower limit of the glass transition temperature Tg is preferably 520 ° C, and more preferably 540 ° C, 560 ° C, 580 ° C, and 600 ° C.

  When the upper limit of the glass transition temperature Tg satisfies the above range, an increase in the annealing temperature of the glass can be suppressed, and thermal damage to annealing equipment, for example, a continuous annealing or a batch annealing furnace called rare, can be reduced. can do.

  When the lower limit of the glass transition temperature Tg satisfies the above range, it becomes easy to maintain the thermal stability of the glass satisfactorily while maintaining the desired Abbe number and refractive index.

<Light transmittance of glass>
In Embodiment 1-1, the light transmittance can be evaluated by the degree of coloring λ5.
Using glass (10.0 mm ± 0.1 mm thick) having two planes which are parallel to each other and optically polished, light rays are incident perpendicularly to this plane from one of the two planes. Let it. Then, the ratio (Iout / Iin) of the intensity Iout of the transmitted light emitted from the other plane and the intensity Iin of the incident light, that is, the external transmittance is calculated. The spectral transmittance curve is obtained by measuring the external transmittance while scanning the wavelength of the incident light in a range of, for example, 280 to 700 nm using a spectrophotometer.

  The external transmittance increases as the wavelength of the incident light increases from the absorption edge on the short wavelength side of the glass toward the long wavelength side, and shows a high value.

  λ5 is a wavelength at which the external transmittance becomes 5%. In the wavelength range of 280 to 700 nm, the external transmittance of glass on the longer wavelength side than λ5 shows a value larger than 5%.

  By using an optical glass having a shorter wavelength of λ5, it is possible to provide an optical element that enables suitable color reproduction.

  For this reason, the range of λ5 is preferably 440 nm or less, and more preferably 435 nm or less, 430 nm or less, 425 nm or less, 420 nm or less, 415 nm or less, and 410 nm or less. The standard of the lower limit of λ5 is 380 nm.

<Specific gravity of glass>
The optical glass according to Embodiment 1-1 is a highly dispersed glass in which the increase in the refractive index is suppressed, but does not have a large specific gravity. Usually, if the specific gravity of the glass can be reduced, the weight of the lens can be reduced. As a result, it is possible to reduce the power consumption of the autofocus driving of the camera lens having the lens. On the other hand, when the specific gravity is excessively reduced, the thermal stability is reduced. Therefore, the upper limit of the specific gravity d is preferably 5.80, and furthermore, 5.60, 5.30, 5.00, 4.80, 4.60, 4.40, 4.20, 4.00. , 3.80, and 3.70 are more preferable. From the viewpoint of improving thermal stability, the lower limit of the specific gravity d is preferably 2.80, and more preferably 2.90, 3.00, 3.10, and 3.20.

<Liquid phase temperature>
The upper limit of the liquidus temperature of the optical glass according to Embodiment 1-1 is preferably 1350 ° C, and more preferably 1340 ° C, 1330 ° C, 1320 ° C, 1310 ° C, and 1300 ° C. The lower limit of the liquidus temperature is preferably 1000 ° C., and more preferably 1020 ° C., 1040 ° C., 1060 ° C., 1080 ° C., 1100 ° C., 1130 ° C., and 1150 ° C. According to the optical glass according to the present embodiment, a high-dispersion glass in which the thermal stability of the glass is improved and the increase in the refractive index is suppressed can be obtained.

  The liquidus temperature is determined as follows. 10 cc (10 ml) of glass is put into a platinum crucible, melted at 1250 ° C. to 1350 ° C. for 20 to 30 minutes, cooled to a glass transition temperature Tg or lower, and put together with the platinum crucible into a melting furnace at a predetermined temperature and held for 2 hours. I do. The holding temperature is 1000 ° C. or more, in steps of 5 ° C. or 10 ° C. After holding for 2 hours, the mixture is cooled, and the presence or absence of crystals inside the glass is observed with a 100-fold optical microscope. The lowest temperature at which no crystals are deposited is taken as the liquidus temperature.

(Manufacture of optical glass)
The optical glass according to the embodiment of the present invention may be prepared by blending glass raw materials so as to have the above-mentioned predetermined composition, and using the prepared glass raw materials according to a known glass manufacturing method. For example, a plurality of types of compounds are prepared and mixed well to form a batch material, and the batch material is placed in a quartz crucible or a platinum crucible and roughly melted (rough melted). The melt obtained by the coarse melting is rapidly cooled and pulverized to produce a cullet. Further, the cullet is put in a platinum crucible, heated and re-melted (remelted) to obtain a molten glass, and after further clarification and homogenization, the molten glass is molded and gradually cooled to obtain an optical glass. Known methods may be applied to the forming and slow cooling of the molten glass.

  The compound used for preparing the batch raw material is not particularly limited as long as a desired glass component can be introduced into the glass so as to have a desired content. Phosphoric acid, metaphosphate, diphosphorus pentoxide, carbonate, nitrate, hydroxide, fluoride and the like.

(Manufacture of optical elements, etc.)
In order to manufacture an optical element using the optical glass according to the embodiment of the 1-1 invention, a known method may be applied. For example, a glass material is melted to form a molten glass, and the molten glass is poured into a mold and formed into a plate shape to produce a glass material made of the optical glass according to the present invention. The obtained glass material is appropriately cut, ground and polished to produce a press-formed glass material having a size and shape suitable for press forming. The glass material for press molding is heated and softened, and press-molded by a known method to produce an optical element blank that approximates the shape of the optical element. The optical element blank is annealed and ground and polished by a known method to produce an optical element.

  The optical function surface of the manufactured optical element may be coated with an antireflection film, a total reflection film, or the like according to the purpose of use.

  Examples of the optical element include various lenses such as a spherical lens, a prism, and a diffraction grating.

1-2 Embodiment The optical glass according to Embodiment 1-2 of the present invention includes:
Abbe number νd is 16.70 or less,
The content of Bi ₂ O ₃ is 29.0% by mass or less,
It is a phosphate optical glass having a total content of TiO ₂ , Nb ₂ O ₅ and WO ₃ of 45.0% by mass or more.

  Hereinafter, the optical glass according to Embodiment 1-2 will be described in detail.

  In the optical glass according to Embodiment 1-2, the Abbe number νd is 16.70 or less. The upper limit of the Abbe number νd is preferably 16.68, and more preferably 16.66, 16.64, 16.62, 16.60, 16.58, 16.56, 16.54. Further, the lower limit of the Abbe number is preferably 15.50, and the larger the value is in the order of 15.55, 15.60, 15.65, 15.70, the more preferable.

  When the Abbe number νd is 16.70 or less, the difference in Abbe number increases when a pair lens is used in combination with a low-dispersion glass lens, and a high effect is obtained in correcting chromatic aberration.

In the optical glass according to Embodiment 1-2, the content of Bi ₂ O ₃ is 29.0% or less.

In the optical glass according to the 1-2 embodiment, the upper limit of the content of Bi ₂ O ₃ is preferably 28.5%, and furthermore, 28.0%, 27.5%, 27.0%, 25.0%, 20.0%, 15.0%, 10.0%, 6.0%, and 5.0% are more preferable. The lower limit of the content of Bi ₂ O ₃ is preferably 0%. The content of Bi ₂ O ₃ may be 0%.

Bi ₂ O ₃ has a function of improving the thermal stability of glass by containing an appropriate amount. On the other hand, when the content of Bi ₂ O ₃ is increased, the refractive index is increased, and the coloring of the glass is increased. Therefore, the content of Bi ₂ O ₃ is in the above range.

In addition, in the optical glass according to the first to second embodiments, when the content of the glass component is represented by cation%, the upper limit of the Bi ³⁺ content is preferably 20.00 cation%, and further, 19. 50 cation%, 19.00 cation%, 18.50 cation%, 18.00 cation%, 17.50 cation%, 17.00 cation%, and 16.50 cation% are more preferable in this order. The lower limit of the Bi ³⁺ content is preferably 3.00 cation%, and more preferably 1.50 cation%, 1.00 cation%, and 0.40 cation%. The content of Bi ³⁺ may be 0 cation%.

Bi ³⁺ has a function of improving the thermal stability of glass by containing an appropriate amount. On the other hand, when the content of Bi ³⁺ is increased, the refractive index increases, and the coloring of the glass increases. Therefore, the content of Bi ³⁺ is preferably in the above range.

In the optical glass according to Embodiment 1-2, the total content of TiO ₂ , Nb ₂ O _5, and WO ₃ [TiO ₂ + Nb ₂ O ₅ + WO ₃ ] is 45.0% or more.

In the optical glass according to Embodiment 1-2, the lower limit of the total content of TiO ₂ , Nb ₂ O _5, and WO ₃ [TiO ₂ + Nb ₂ O ₅ + WO ₃ ] is preferably 46.0%, and Is more preferable in the order of 47.0%, 48.0%, 49.0%, and 50.0%. Further, the upper limit of the total content [TiO ₂ + Nb ₂ O ₅ + WO ₃ ] is preferably 85.0%, further 84.0%, 83.0%, 82.0%, 81.0%. , 79.0%, and 77.0% are more preferable.

TiO ₂ , Nb ₂ O ₅ and WO ₃ suppress the increase in the refractive index nd and contribute to high dispersion of the glass. Also, by containing an appropriate amount, it also has a function of improving the thermal stability of the glass. From the viewpoint of increasing the dispersion of the glass and improving the thermal stability of the glass, the lower limit of the total content [TiO ₂ + Nb ₂ O ₅ + WO ₃ ] is in the above range. From the viewpoint of suppressing the increase in the refractive index and the increase in the coloring of the glass, the upper limit of the total content [TiO ₂ + Nb ₂ O ₅ + WO ₃ ] is preferably within the above range.

The optical glass according to the first to second embodiments is a phosphate optical glass. The phosphate optical glass refers to an optical glass mainly containing a phosphate as a glass network forming component. Therefore, the optical glass according to the first to second embodiments contains a phosphate as a network-forming component, and the content is expressed as the content of P ₂ O ₅ . P ₂ O ₅ , Al ₂ O ₃ , B ₂ O ₃ , SiO _{2 and the} like are known as glass network forming components. Here, “mainly containing a phosphate as a glass network forming component” means that the content of P ₂ O ₅ in mass% is higher than the content of any of Al ₂ O ₃ , B ₂ O ₃ , and SiO _2. Also means a lot of glass.

In the optical glass according to the 1-2 embodiment, the lower limit of the content of P ₂ O ₅ is preferably 7.0%, and further, 8.0%, 9.0%, 10.0%, It is more preferable in the order of 10.5% and 11.0%. The upper limit of the content of P ₂ O ₅ is preferably 35.0%, and more preferably 34.5%, 34.0%, 33.5%, and 33.0%.

P ₂ O ₅ is a component necessary for glass to contain many highly dispersed components. On the other hand, if P ₂ O ₅ is excessively contained, the meltability deteriorates. Therefore, in the glass according to the present embodiment, the content of P ₂ O ₅ is preferably in the above range.

In the optical glass according to Embodiment 1-2, when the content of the glass component is represented by cation%, the upper limit of the P ⁵⁺ content is preferably 45.00 cation%, and more preferably 44.00 cation%. 50 cation%, 44.00 cation%, 43.50 cation%, 43.00 cation%, 42.50 cation%, 42.00 cation%, 41.50 cation%, 41.00 cation%, 40.50 cation %, 40.00 cation%, 39.50 cation%, 39.00 cation%, 38.50 cation%. The lower limit of the P ⁵⁺ content is preferably 20.00 cation%, more preferably 20.50 cation%, 21.00 cation%, 21.50 cation%, 22.00 cation%, 22.50 cation% %, 23.00 cation%, 23.50 cation%, 24.00 cation%, 24.50 cation%, 25.00 cation%, and 25.50 cation% in this order.

P ⁵⁺ is an essential component for suppressing an increase in the refractive index nd and for containing a large amount of highly dispersed components in glass. On the other hand, when P ⁵⁺ is excessively contained, the meltability deteriorates. Therefore, in the optical glass according to the present embodiment, the content of P ⁵⁺ is preferably in the above range.

In the optical glass according to the 1-2 embodiment, the mass of the total content of TiO ₂ , Nb ₂ O ₅ and WO _{3 and} the total content of TiO ₂ , Nb ₂ O ₅ , WO ₃ and Bi ₂ O ₃ the lower limit of the ratio _{[(TiO 2 + Nb 2 O} 5 + WO 3) / (TiO 2 + Nb 2 O 5 + WO 3 + Bi 2 O 3)] is preferably 0.45, more, 0.50,0.55 , 0.60, 0.65, 0.70, 0.75, 0.80, 0.85. The upper limit of the mass ratio [(TiO ₂ + Nb ₂ O ₅ + WO ₃ ) / (TiO ₂ + Nb ₂ O ₅ + WO ₃ + Bi ₂ O ₃ )] is preferably 1.00. The content of Bi ₂ O ₃ may be 0%.

By setting the value of the mass ratio [(TiO ₂ + Nb ₂ O ₅ + WO ₃ ) / (TiO ₂ + Nb ₂ O ₅ + WO ₃ + Bi ₂ O ₃ )] in the above range, deterioration of the transmittance is suppressed and refraction is performed. The rate increase can be suppressed.

In the optical glass according to the 1-2 embodiment, the lower limit of the mass ratio [TiO ₂ / Nb ₂ O ₅ ] of the content of TiO _{2 and} the content of Nb ₂ O ₅ is preferably 0.15, Furthermore, it is more preferable in the order of 0.16, 0.17, 0.18, 0.19, 0.20, 0.23. The upper limit of the mass ratio [TiO ₂ / Nb ₂ O ₅ ] is preferably 4.50, and furthermore, 4.40, 4.30, 4.20, 4.10, 4.00, 3.80. , More preferably 3.60.

TiO ₂ tends to lower the meltability of the glass and increase the liquidus temperature. On the other hand, Nb ₂ O ₅ suppresses a decrease in liquidus temperature and an increase in refractive index, and contributes to high dispersion. Therefore, by including Nb ₂ O ₅ at a fixed ratio to TiO ₂ , it is possible to suppress a decrease in the meltability of the glass and an increase in the liquidus temperature. Therefore, in the optical glass according to the present embodiment, the mass ratio [TiO ₂ / Nb ₂ O ₅ ] is preferably in the above range.

In the optical glass according to Embodiment 1-2, when the content of the glass component is represented by cation%, the cation ratio [Ti ⁴⁺ / Nb ⁵ ] between the content of Ti ^{4+ and} the content of Nb ^{5+. +} ] Is preferably 6.00, and more preferably 5.90, 5.80, 5.70, 5.65, 5.60. The lower limit of the cation ratio [Ti ⁴⁺ / Nb ⁵⁺ ] is preferably 0.40, and more preferably 0.41 and 0.42.

Ti ⁴⁺ tends to lower the meltability of the glass and increase the liquidus temperature. On the other hand, Nb ⁵⁺ suppresses a decrease in liquidus temperature and an increase in refractive index, and contributes to high dispersion. Therefore, by including Nb ⁵⁺ at a fixed ratio to Ti ⁴⁺ , it is possible to suppress a decrease in glass meltability and an increase in liquidus temperature. Therefore, in the optical glass according to the present embodiment, the cation ratio [Ti ⁴⁺ / Nb ⁵⁺ ] is preferably in the above range.

In the optical glass according to the 1-2 embodiment, the lower limit of the mass ratio [(TiO ₂ + WO ₃ ) / Nb ₂ O ₅ ] of the total content of TiO ₂ and WO _{3 to} the content of Nb ₂ O ₅ is as follows: It is preferably 0.15, and more preferably 0.17, 0.19, 0.20, 0.21, 0.23, 0.25, 0.26, 0.28, 0.30, 0.35. , 0.40, 0.45, 0.50, 0.55, 0.56, 0.57, 0.58, 0.59, 0.60, 0.61, 0.62, 0.63, 0 .64, then 0.65. The upper limit of the mass ratio [(TiO ₂ + WO ₃ ) / Nb ₂ O ₅ ] is preferably 8.00, and 7.90, 7.80, 7.70, 7.60, and 7. 40, 7.20, and 7.00 are more preferable.

By setting the value of the mass ratio [(TiO ₂ + WO ₃ ) / Nb ₂ O ₅ ] in the above range, it is possible to obtain a glass having high dispersion suitable for correcting chromatic aberration while suppressing an increase in the refractive index. .

In the optical glass according to Embodiment 1-2, when the content of the glass component is represented by cation%, the cation ratio of the total content of Ti ⁴⁺ and W ^{6+ to} the content of Nb ⁵⁺ [( Ti ⁴⁺ + W ⁶⁺ ) / Nb ⁵⁺ ] is preferably 7.70, more preferably 7.60, 7.50, 7.40, 7.35, 7.30, 7.28, 7.26 is more preferred. The lower limit of the cation ratio [(Ti ⁴⁺ + W ⁶⁺ ) / Nb ⁵⁺ ] is preferably 0.40, and more preferably 0.41 and 0.42.

By setting the value of the cation ratio [(Ti ⁴⁺ + W ⁶⁺ ) / Nb ⁵⁺ ] in the above range, it is possible to obtain a glass having high dispersion suitable for correcting chromatic aberration while suppressing an increase in the refractive index. it can.

In the optical glass according to Embodiment 1-2, when the content of the glass component is represented by cation% and the content of W ⁶⁺ exceeds 0 cation%, the content of Ba ²⁺ and W The upper limit of the cation ratio [Ba ²⁺ / W ⁶⁺ ] with respect to the content of ⁶⁺ is preferably 0.14, and further in the order of 0.13, 0.12, 0.11, and 0.10. preferable.

Ba ²⁺ is a component that contributes to low dispersion. Therefore, in the optical glass according to the first to second embodiments, the desired high dispersibility can be obtained by adding W ⁶⁺ , which is a high dispersing component, to the above cation ratio with respect to the content of Ba ²⁺ . Can be maintained.

In the optical glass according to Embodiment 1-2, when the content of the glass component is represented by cation%, the content of W ⁶⁺ is 0 cation%, and the content of Ba ²⁺ is 0 cation%. When it exceeds, the upper limit of the total content of Ti ⁴⁺ and Bi ³⁺ [Ti ⁴⁺ + Bi ³⁺ ] is preferably 35.00 cation%, more preferably 34.00 cation%, 33.00. Cation%, 32.50 cation%, 32.30 cation%, 32.00 cation%, 31.80 cation%, 31.60 cation%, 31.40 cation%, 31.20 cation%, 31.00 cation% , 30.80 cation%, 30.60 cation%, 30.40 cation%, 30.20 cation%, 30.10 cation%, and 30.00 cation% in this order. The lower limit of the total content [Ti ⁴⁺ + Bi ³⁺ ] is preferably 21.00 cation%, more preferably 21.20 cation%, 21.40 cation%, 21.60 cation%, and 21.80 cation%. 2,2.00 cation%, 22.20 cation%, 22.40 cation%, 22.60 cation%, 22.80 cation%, 23.00 cation%, 23.10 cation%, 23.20 cation%, 23 More preferably, in the order of .30 cation%, 23.40 cation%, and 23.50 cation%.

When the content of W ⁶⁺ is 0 cation% and the content of Ba ²⁺ exceeds 0 cation%, Ti has the largest contribution to high dispersion after W ⁶⁺ among the high dispersion components. ^By setting the total content of ⁴⁺ and Bi ³⁺ having the function of improving thermal stability in the above range, it is possible to suppress the low dispersion by Ba ²⁺ .

  In the optical glass according to the 1-2 embodiment, the upper limit of the refractive index nd is preferably 2.1500, and further, 2.1300, 2.1100, 2.1000, 2.0900, 2.0700, 2.0500, 2.0300, 2.0140, and 2.000 are more preferred. In addition, the lower limit of the refractive index nd is preferably 1.8800, and the smaller the values are, in order of 1.9000, 1.9200, 1.9400, and 1.9600, the more preferable.

  By setting the refractive index nd within the above range, even when a pair lens is used in combination with a low-dispersion glass lens having a low refractive index, field curvature can be suppressed because the difference in refractive index is small.

  The other glass component compositions in the first to second embodiments can be the same as those in the first to first embodiments. Further, the glass properties, the production of optical glass, and the production of optical elements and the like in the first to second embodiments can be the same as those in the first to first embodiments.

Second Embodiment The following 2-1 embodiment and 2-2 embodiment (hereinafter, may be collectively referred to as “second embodiment”) include glass, optical glass, and the like that can easily reduce the reduction color. The present invention relates to a glass material for polishing, a glass material for press molding, and an optical element.

  In the second embodiment of the present invention, it is an object of the present invention to provide a glass capable of shortening the heat treatment time when the reduction color is reduced by the heat treatment.

When Li ₂ O is contained as a glass component, the Abbe number ν _d increases, and the thermal stability of the glass decreases. For this reason, Li ₂ O is not usually contained in highly dispersed glass.

In the high-dispersion glass of the second embodiment of the present invention, TiO ₂ , Nb ₂ O ₅ , WO are contained by adding Li ₂ O as a glass component while maintaining high dispersibility by lowering the Abbe number ν _{d. The} heat treatment time required to reduce the reduced color due to highly dispersed components such as ₃ and Bi ₂ O ₃ can be reduced.

When an alkali metal oxide such as Li ₂ O is contained as a glass component, the melting temperature decreases, and accordingly, the glass transition temperature Tg also decreases. Some conventional precision press glasses contain Li ₂ O to lower the glass transition temperature Tg to facilitate processing. Here, in the glass containing Li ₂ O in order to lower the glass transition temperature Tg, the reduction reaction of the highly dispersed component does not proceed so much in the melting process because the melting temperature is low, so that the degree of coloring of the glass is light, Does not require long heat treatment. Therefore, when Li ₂ O is contained in order to lower the melting temperature as in the conventional glass, a long-time heat treatment is not required so as to affect the production process, so that it is necessary to reduce the reduction color. The problem of shortening the heat treatment time was not recognized.

The second embodiment of the present invention relates to a high-dispersion glass in which a reduction color caused by a high-dispersion component such as TiO ₂ , Nb ₂ O ₅ , WO ₃ and Bi ₂ O ₃ becomes a problem. It is based on the finding that by containing Li ₂ O which is not usually contained, the heat treatment time required for reducing the reduction color can be shortened, and is obtained by containing Li ₂ O as a glass component. As an effect obtained, an extremely novel effect is used.

  According to the second embodiment of the present invention, when reducing color is reduced by heat treatment in highly dispersed glass, the heat treatment time can be shortened.

In the glass according to the second embodiment of the present invention, the content of Li ₂ O was determined by ICP-MS (Inductively Coupled Plasma-Mass Spectrometry), and the content of glass components other than Li ₂ O was determined by ICP-AES. (Inductively Coupled Plasma-Atomic Emission Spectrometry). The analysis value obtained by ICP-AES may include, for example, a measurement error of about ± 5% of the analysis value. Further, in the present specification and the present invention, a content of 0% or no glass component means that the component is not substantially contained, and the content of the component is substantially equal to the impurity level. Indicates that:

Glass 2-1 embodiment of the 2-1 embodiment the present invention,
Abbe number ν _d is 18.10 or less,
The total content of TiO ₂ , Nb ₂ O ₅ , WO ₃ and Bi ₂ O ₃ [TiO ₂ + Nb ₂ O ₅ + WO ₃ + Bi ₂ O ₃ ] is 30% by mass or more, and the content of Bi ₂ O ₃ is 38% by mass. % Or less phosphate glass,
Content of Li ₂ O, TiO _2, Nb ₂ O _5, the mass ratio of the total content of WO ₃ and _{Bi 2 O 3 [Li 2 O} / (TiO 2 + Nb 2 O 5 + WO 3 + Bi 2 O 3)] Multiplied by 100 is 0.015 to 0.770.

  Hereinafter, the glass according to Embodiment 2-1 will be described in detail.

In the glass according to the second embodiment, the Abbe number ν _d is 18.10 or less. The upper limit of the Abbe number ν _d is preferably 18.05, and further, 18.00, 17.90, 17.80, 17.70, 17.60, 17.50, 17.40, 17.30. , 17.20, 17.10, 17.00, 16.90, 16.80, 16.78. Further, the lower limit of the Abbe number is preferably 15.00, and further, 15.10, 15.20, 15.25, 15.30, 15.35, 15.40, 15.45, 15.50. , 15.52, 15.54, 15.56, 15.58, 15.60.

Abbe number [nu _d by a 18.10 or less, exhibited when paired lens in combination with a low-dispersion glass lens, the difference between the Abbe numbers with increases, a higher effect in the correction of chromatic aberration.

In the glass according to the _second embodiment, the total content of TiO ₂ , Nb ₂ O ₅ , WO ₃ and Bi ₂ O ₃ [TiO ₂ + Nb ₂ O ₅ + WO ₃ + Bi ₂ O ₃ ] is 30% or more. . The lower limit of the total content [TiO ₂ + Nb ₂ O ₅ + WO ₃ + Bi ₂ O ₃ ] is preferably 35%, and further, 36%, 38%, 40%, 42%, 44%, 46%, 48 %, 50%, 52%, 54%, 56%, 58%, 60%, 62%, and 64% are more preferable. The upper limit of the total content [TiO ₂ + Nb ₂ O ₅ + WO ₃ + Bi ₂ O ₃ ] is preferably 90%, and further, 88%, 86%, 85%, 84%, 83%, 82%. , 81%, 80%, 79%, 78%, 77% in this order.

TiO ₂ , Nb ₂ O ₅ , WO ₃ and Bi ₂ O ₃ contribute to high dispersion of glass. Also, by containing an appropriate amount, it also has a function of improving the thermal stability of the glass. Therefore, the lower limit of the total content [TiO ₂ + Nb ₂ O ₅ + WO ₃ + Bi ₂ O ₃ ] is preferably within the above range. On the other hand, TiO ₂ , Nb ₂ O ₅ , WO ₃ and Bi ₂ O ₃ increase the coloring of the glass. Therefore, the upper limit of the total content [TiO ₂ + Nb ₂ O ₅ + WO ₃ + Bi ₂ O ₃ ] is preferably in the above range.

In the glass according to the second embodiment, when the content of the glass component is represented by cation%, the total content of Ti ⁴⁺ , Nb ⁵⁺ , W ⁶⁺ and Bi ³⁺ [Ti ⁴⁺ + Nb ^{5 +} + W ⁶⁺ + Bi ³⁺ ] is preferably 75.00 cation%, more preferably 74.50 cation%, 74.00 cation%, 73.50 cation%, 73.00 cation%, 72.00 cation%. 50 cation%, 72.00 cation%, 71.50 cation%, 71.00 cation%, and 70.50 cation% are more preferable in this order. The lower limit of the total content [Ti ⁴⁺ + Nb ⁵⁺ + W ⁶⁺ + Bi ³⁺ ] is preferably 52.00 cation%, more preferably 52.10 cation%, 52.15 cation%, and 52.20 cation%. , 52.25 cation%, and 52.30 cation%.

Ti ⁴⁺ , Nb ⁵⁺ , W ⁶⁺ and Bi ³⁺ contribute to high dispersion of glass. Also, by containing an appropriate amount, it also has a function of improving the thermal stability of the glass. Therefore, the lower limit of the total content [Ti ⁴⁺ + Nb ⁵⁺ + W ⁶⁺ + Bi ³⁺ ] is preferably in the above range. On the other hand, Ti ⁴⁺ , Nb ⁵⁺ , W ⁶⁺ and Bi ³⁺ increase the coloring of the glass. Therefore, the upper limit of the total content [Ti ⁴⁺ + Nb ⁵⁺ + W ⁶⁺ + Bi ³⁺ ] is preferably within the above range.

In the glass according to the _second embodiment, the content of Bi ₂ O ₃ is 38% or less. The upper limit of the content of Bi ₂ O ₃ is preferably 35%, and more preferably 33%, 30%, 28%, 25%, 23%, and 20%. The lower limit of the content of Bi ₂ O ₃ is preferably 0%. The content of Bi ₂ O ₃ may be 0%.

Bi ₂ O ₃ is a component that contributes to high dispersion. Further, by setting the content of Bi ₂ O ₃ within the above range, an increase in specific gravity and a decrease in glass transition temperature Tg can be suppressed. As the specific gravity of the glass increases, the mass of the optical element increases. For example, when a lens having a large mass is incorporated in an autofocus type imaging lens, the power required for driving the lens during autofocus increases, and the battery is significantly consumed. Therefore, the content of Bi ₂ O ₃ is preferably set in the above range.

Bi ₂ O ₃ has a function of greatly increasing the refractive index as compared with other high dispersion components TiO ₂ , Nb ₂ O ₅ , and WO ₃ . When the refractive index is greatly increased, when used in combination with a low-dispersion glass lens having a low refractive index to correct chromatic aberration, the curvature of field tends to be strong due to a large refractive index difference. Therefore, the content of Bi ₂ O ₃ is preferably set in the above range.

In addition, in the glass according to the second embodiment, when the content of the glass component is represented by cation%, the upper limit of the Bi ³⁺ content is preferably 10.00 cation%, and further 9.00. Cation%, 8.00 cation%, 7.00 cation%, 6.00 cation%, 5.00 cation%, 4.50 cation%, 4.00 cation%, 3.50 cation%, 3.00 cation% , 2.50 cation%, 2.00 cation%, 1.50 cation%, and 1.00 cation%. The content of Bi ³⁺ may be 0 cation%.

Bi ³⁺ is a component that contributes to high dispersion. Further, when the content of Bi ³⁺ is in the above range, an increase in specific gravity and a decrease in glass transition temperature Tg can be suppressed. As the specific gravity of the glass increases, the mass of the optical element increases. For example, when a lens having a large mass is incorporated in an autofocus type imaging lens, the power required for driving the lens during autofocus increases, and the battery is significantly consumed. Therefore, the content of Bi ³⁺ is preferably in the above range.

Bi ³⁺ has a function of greatly increasing the refractive index as compared with other high dispersion components Ti ⁴⁺ , Nb ⁵⁺ , and W ⁶⁺ . When the refractive index is greatly increased, when used in combination with a low-dispersion glass lens having a low refractive index to correct chromatic aberration, the curvature of field tends to be strong due to a large refractive index difference. Therefore, the content of Bi ³⁺ is preferably in the above range.

The glass according to Embodiment 2-1 is phosphate glass. The phosphate glass refers to a glass mainly containing a phosphate as a glass network forming component. Therefore, the glass according to Embodiment 2-1 mainly includes a phosphate as a network-forming component, and the content is expressed as the content of P ₂ O ₅ . P ₂ O ₅ , Al ₂ O ₃ , B ₂ O ₃ , SiO _{2 and the} like are known as glass network forming components. Here, “mainly containing a phosphate as a glass network forming component” means that the content of P ₂ O ₅ in mass% is higher than the content of any of Al ₂ O ₃ , B ₂ O ₃ , and SiO _2. Also means a lot of glass.

In the glass according to the _second embodiment, the lower limit of the content of P ₂ O ₅ is preferably 7.0%, and further, 8.0%, 9.0%, 10.0%, and 11%. 1.0%, 12.0%, 13.0%, 14.0%, 15.0%, 16.0%, 17.0%, 18.0%, 19.0%, 20.0% Is more preferable. Further, the upper limit of the content of P ₂ O ₅ is preferably 37.0%, and further, 36.0%, 35.0%, 34.5%, 34.0%, 33.5%, 33.0%, 32.5%, 32.0%, 31.5%, 31.0%, 30.5%, and 30.0% are more preferable.

P ₂ O ₅ is a component necessary for glass to contain many highly dispersed components. On the other hand, if P ₂ O ₅ is excessively contained, the meltability deteriorates. Therefore, in the glass according to the present embodiment, the content of P ₂ O ₅ is preferably in the above range.

In addition, in the glass according to the 2-1 embodiment, when the content of the glass component is represented by cation%, the upper limit of the content of P ⁵⁺ is preferably 42.00 cation%, and further 41.50. Cation%, 41.00 cation%, 40.50 cation%, 40.00 cation%, 39.50 cation%, 39.00 cation%, 38.50 cation%, 38.00 cation%, 37.50 cation% , 37.00 cation%, 36.50 cation%, 36.00 cation%. The lower limit of the content of P ⁵⁺ is preferably 25.00 cation%, more preferably 25.50 cation%, 26.00 cation%, 26.50 cation%, 27.00 cation%, and 27.50 cation%. %, 28.00 cation%, 28.50 cation%, 29.00 cation%, and 29.30 cation% in this order.

P ⁵⁺ is an essential component for suppressing an increase in the refractive index nd and for containing a large amount of highly dispersed components in glass. On the other hand, when P ⁵⁺ is excessively contained, the meltability deteriorates. Therefore, in the optical glass according to the present embodiment, the content of P ⁵⁺ is preferably in the above range.

In the glass according to the 2-1 embodiment, the mass ratio of the content and the total content of _{TiO 2, Nb 2 O 5,} WO 3 and Bi ₂ O ₃ of _{Li 2 O [Li 2 O /} (TiO 2 + Nb ₂ O ₅ + WO ₃ + Bi ₂ O ₃ )] multiplied by 100 is 0.015 to 0.770. The lower limit of the value obtained by multiplying the mass ratio [Li ₂ O / (TiO ₂ + Nb ₂ O ₅ + WO ₃ + Bi ₂ O ₃ )] by 100 is preferably 0.017, more preferably 0.019, 0.021. , 0.023, 0.025, 0.027, 0.030. The upper limit of the value obtained by multiplying the mass ratio [Li ₂ O / (TiO ₂ + Nb ₂ O ₅ + WO ₃ + Bi ₂ O ₃ )] by 100 is preferably 0.750, more preferably 0.730,0. .710, 0.700, 0.680, 0.650, 0.600, and 0.550 are more preferable.

By setting the value obtained by multiplying the mass ratio [Li ₂ O / (TiO ₂ + Nb ₂ O ₅ + WO ₃ + Bi ₂ O ₃ )] by 100 to the above range, the reduction of the coloring by the heat treatment is sufficiently promoted. If the value obtained by multiplying the mass ratio [Li ₂ O / (TiO ₂ + Nb ₂ O ₅ + WO ₃ + Bi ₂ O ₃ )] by 100 exceeds 0.750, the desired high dispersion property cannot be obtained, and Stability is impaired.

In the glass according to the second embodiment, when the content of the glass component is represented by cation% and the content of W ⁶⁺ exceeds 0 cation%, the content of Ba ²⁺ and W ⁶ The upper limit of the cation ratio [Ba ²⁺ / W ⁶⁺ ] to the content of ⁺ is preferably 0.14, and more preferably 0.13, 0.12, 0.11, and 0.10. .

Ba ²⁺ is a component that contributes to low dispersion. Therefore, in the glass according to the second embodiment, the desired high dispersibility can be obtained by adding W ⁶⁺ , which is a high dispersing component, to the content of Ba ²⁺ so as to have the above cation ratio. Can be maintained.

Further, in the glass according to the second embodiment, when the content of the glass component is represented by cation%, the content of W ⁶⁺ is 0 cation% and the content of Ba ²⁺ is 0 cation. %, The upper limit of the total content of Ti ⁴⁺ and Bi ³⁺ [Ti ⁴⁺ + Bi ³⁺ ] is preferably 35.00 cation%, more preferably 34.00 cation%, and 33.3 cation%. 00 cation%, 32.50 cation%, 32.30 cation%, 32.00 cation%, 31.80 cation%, 31.60 cation%, 31.40 cation%, 31.20 cation%, 31.00 cation %, 30.80 cation%, 30.60 cation%, 30.40 cation%, 30.20 cation%, 30.10 cation%, and 30.00 cation% in this order. The lower limit of the total content [Ti ⁴⁺ + Bi ³⁺ ] is preferably 21.00 cation%, more preferably 21.20 cation%, 21.40 cation%, 21.60 cation%, and 21.80 cation%. 2,2.00 cation%, 22.20 cation%, 22.40 cation%, 22.60 cation%, 22.80 cation%, 23.00 cation%, 23.10 cation%, 23.20 cation%, 23 More preferably, in the order of .30 cation%, 23.40 cation%, and 23.50 cation%.

When the content of W ⁶⁺ is 0 cation% and the content of Ba ²⁺ exceeds 0 cation%, Ti has the largest contribution to high dispersion after W ⁶⁺ among the high dispersion components. ^By setting the total content of ⁴⁺ and Bi ³⁺ having the function of improving thermal stability in the above range, it is possible to suppress the low dispersion by Ba ²⁺ .

(Glass component)
Preferred aspects of the glass according to the above-described Embodiment 2-1 will be described in detail below.

In the glass according to the _second embodiment, the lower limit of the content of Li ₂ O is preferably 0.010%, and more preferably 0.012%, 0.014%, 0.016%, and 0.1%. 018% and 0.020% are more preferable. The upper limit of the content of Li ₂ O is preferably 0.640%, and further, 0.630%, 0.620%, 0.610%, 0.600%, 0.580%, 0.560%. %, 0.540%, 0.520%, 0.500%, 0.490%, 0.480%, 0.470%, 0.460%, 0.450%, 0.440%, 0.430 %, 0.420%, 0.410%, 0.400%, 0.390%, 0.380%, 0.370%, 0.360%, 0.350%, and 0.340% in this order. .

By setting the content of Li ₂ O within the above range, the heat treatment time required to reduce the reduction color caused by highly dispersed components such as TiO ₂ , Nb ₂ O ₅ , WO ₃ and Bi ₂ O ₃ can be reduced. . Further, a decrease in the glass transition temperature Tg can be suppressed. On the other hand, if the content of Li ₂ O is too large, the Abbe number ν _d may increase, and the thermal stability of the glass may decrease.

In the glass according to the 2-1 embodiment, the lower limit of the value of βOH represented by the following formula (1) is preferably 0.05 mm ⁻¹ , and more preferably 0.10 mm ⁻¹ and 0.15 mm ^{−. 1} , 0.20 mm ^-1 , 0.25 mm ^-1 , 0.30 mm ^-1 , and 0.35 mm ^-1 are more preferable. The upper limit value of βOH is preferably 4.00 mm ^{-1, further, 3.90mm -1, 3.80mm -1, 3.70mm} -1, 3.60mm -1, 3.50mm - ^{1, 3.40mm -1, 3.30mm -1,} 3.20mm -1, 3.10mm -1, 3.00mm -1, 2.90mm -1, 2.80mm -1, 2.70.mm - ^{1, 2.60mm -1, 2.50mm -1,} 2.40mm -1, 2.30mm -1, 2.25mm -1, 2.20mm -1, 2.10mm -1, of 2.00 mm ^-1 More preferred in order.

βOH = − [ln (D / C)] / t (1)
Here, in the above formula (1), t represents the thickness (mm) of the glass used for measuring the external transmittance, and C represents a wavelength of 2500 nm when light is incident on the glass in a direction parallel to the thickness direction. Represents the external transmittance (%), and D represents the external transmittance (%) at a wavelength of 2900 nm when light is incident on the glass in a direction parallel to the thickness direction. Ln is a natural logarithm. The unit of βOH is mm ⁻¹ .

  The “external transmittance” is a ratio of the intensity Iout of the transmitted light transmitted through the glass to the intensity Iin of the incident light incident on the glass (Iout / Iin), that is, the transmittance in consideration of the surface reflection on the surface of the glass. It is. The transmittance is obtained by measuring a transmission spectrum using a spectrophotometer. “UV-3100 (Shimadzu)” can be used as the spectroscopic device.

  ΒOH represented by the above formula (1) is defined based on the fact that the transmittance changes due to absorption of light caused by a hydroxyl group. Therefore, by evaluating βOH, the concentration of water (and / or hydroxide ions) contained in the glass can be evaluated. That is, a glass having a high βOH has a high concentration of water (and / or hydroxide ion) contained in the glass.

  By setting the value of βOH within the above range, the amount of noble metal such as platinum derived from the glass melting vessel can be reduced in the glass, and the transmittance after the heat treatment after reducing the reduced color, that is, improving the transmittance. it can. Further, the heat treatment time required for reducing the reduction color can be further reduced. On the other hand, if the value of βOH is too large, the devitrification resistance of the glass may decrease, and the amount of volatiles from the molten glass may increase.

  The method of increasing the βOH value of the glass is not particularly limited, but preferably includes a method of increasing the amount of water in the molten glass in the melting step. As a method of increasing the amount of water in the molten glass, for example, a treatment of adding water vapor to the melting atmosphere, a treatment of bubbling a gas containing water vapor in the molten glass, or the like can be mentioned.

Glass according to the 2-1 embodiment preferably contain Nb ₂ O _5. In the glass according to the present embodiment, the lower limit of the content of Nb ₂ O ₅ is preferably 5.0%, and more preferably 5.5%, 6.0%, 6.5%, and 7.0%. , 7.5%, 8.0%, 8.5%, 9.0%, 9.5%, 10.0%, 10.5%, 11.0%, 11.5%, 12.0% , 12.5%, 13.0%, 13.5%, 14.0%, 14.5%, 15.5%, 16.0%, 16.5%, 17.0%, 17.5% , 18.0%, 18.5%, 19.0%, 19.5%, 20.0%, 20.5%, 21.0%, 21.5%, 22.0%, 22.5% , 23.0%. The upper limit of the content of Nb ₂ O ₅ is preferably 60.0%, and more preferably 59.0%, 58.0%, 57.0%, 56.0%, 55.0%, 54.0%, 53.0%, 52.0%, 51.0%, 50.0%, 49.0%, 48.0%, 47.0%, 46.0%, 45.0%, 44.0%, 43.0%, 42.0%, 41.0%, 40.0%, 39.0%, 38.0%, and 37.0% are more preferable.

Nb ₂ O ₅ is a component that contributes to high dispersion. It is also a glass component that improves the thermal stability and chemical durability of the glass. On the other hand, if the content of Nb ₂ O ₅ is too large, the thermal stability of the glass tends to decrease, and the coloring of the glass tends to increase. Therefore, in the glass according to this embodiment, the content of Nb ₂ O ₅ is preferably in the above range.

In addition, in the glass according to the 2-1 embodiment, when the content of the glass component is represented by cation%, the upper limit of the content of Nb ⁵⁺ is preferably 30.00 cation%, and further 29.00. Cation%, 28.50 cation%, 28.00 cation%, 27.50 cation%, 27.00 cation%, 26.50 cation%, 26.00 cation%, 25.50 cation%, 25.00 cation% , 24.50 cation%. The lower limit of the Nb ⁵⁺ content is preferably 10.00 cation%, more preferably 11.00 cation%, 12.00 cation%, 12.50 cation%, 13.00 cation%, 13.50 cation%. %, 14.00 cation%, 14.50 cation%, 15.00 cation%, 15.50 cation%, 16.00 cation%, 16.50 cation%, 17.00 cation%, 17.50 cation% More preferred in order.

Nb ⁵⁺ is a component that contributes to high dispersion. It is also a glass component that improves the thermal stability and chemical durability of the glass. On the other hand, if the content of Nb ⁵⁺ is too large, the thermal stability of the glass tends to decrease, and the coloring of the glass tends to increase. Therefore, in the glass according to the present embodiment, the content of Nb ⁵⁺ is preferably in the above range.

Glass according to the 2-1 embodiment preferably contains TiO _2. In the glass according to the present embodiment, the lower limit of the content of TiO ₂ is preferably 5.0%, and further, 6.0%, 7.0%, 8.0%, 9.0%, and 10%. 1.0%, 11.0%, 12.0%, 13.0%, 14.0%, 15.0%, 16.0%, 17.0%, 18.0%, 19.0% Is more preferable. The upper limit of the content of TiO ₂ is preferably 50.0%, and more preferably 49.0%, 48.0%, 47.0%, 46.0%, 45.0%, and 44.4%. 0%, 43.0%, 42.0%, 41.0%, 40.0%, 39.0%, 38.0%, 37.0%, 36.0%, 35.0%, 34. 0%, 33.0%, 32.0%, 31.0% are more preferable.

TiO ₂ , like Nb ₂ O ₅ , WO ₃ and Bi ₂ O ₃ , greatly contributes to high dispersion. On the other hand, TiO ₂ relatively easily increases the coloring of the glass. Therefore, in the glass according to the present embodiment, the TiO ₂ content is preferably in the above range.

In addition, in the glass according to the second embodiment, when the content of the glass component is represented by cation%, the upper limit of the content of Ti ⁴⁺ is preferably 40.00 cation%, and further 39.00. % Cation, 38.00 cation%, 37.50 cation%, 37.00 cation%, 36.50 cation%, 36.00 cation%, 35.50 cation%, 35.00 cation%, 34.50 cation% Are more preferable. The lower limit of the content of Ti ⁴⁺ is preferably 20.00 cation%, more preferably 21.00 cation%, 21.50 cation%, 22.00 cation%, 22.50 cation%, and 23.00 cation%. %, 23.50 cation%, 24.00 cation%, 24.50 cation%, and 25.00 cation% in this order.

Ti ⁴⁺ , like Nb ⁵⁺ , W ⁶⁺ and Bi ³⁺ , greatly contributes to high dispersion. On the other hand, TiO ₂ relatively easily increases the coloring of the glass. Therefore, in the glass according to the present embodiment, the content of Ti ⁴⁺ is preferably in the above range.

In the glass according to the _second embodiment, the lower limit of the mass ratio [TiO ₂ / Nb ₂ O ₅ ] of the content of TiO _{2 and} the content of Nb ₂ O ₅ is preferably 0.16, and furthermore, Is more preferable in the order of 0.17, 0.18, 0.19, 0.20, 0.23. The upper limit of the mass ratio [TiO ₂ / Nb ₂ O ₅ ] is preferably 4.50, and furthermore, 4.40, 4.30, 4.20, 4.10, 4.00, 3.80. , More preferably 3.60.

TiO ₂ tends to lower the meltability of the glass and increase the liquidus temperature. On the other hand, Nb ₂ O ₅ suppresses a decrease in liquidus temperature and an increase in refractive index, and contributes to high dispersion. Therefore, by containing NNb ₂ O ₅ at a fixed ratio to TiO ₂ , it is possible to suppress a decrease in glass meltability and an increase in liquidus temperature. Therefore, in the glass according to the present embodiment, the cation ratio [TiO ₂ / Nb ₂ O ₅ ] is preferably in the above range.

Further, in the glass according to the 2-1 embodiment, when displaying the content of the glass component in cationic%, the cation ratio of the content and Nb ⁵⁺ content of Ti ⁴⁺ [Ti ⁴⁺ / Nb ⁵⁺ ] Is preferably 6.00, more preferably 5.90, 5.80, 5.70, 5.65, 5.60. The lower limit of the cation ratio [Ti ⁴⁺ / Nb ⁵⁺ ] is preferably 0.40, and more preferably 0.41 and 0.42.

Ti ⁴⁺ tends to lower the meltability of the glass and increase the liquidus temperature. On the other hand, Nb ⁵⁺ suppresses a decrease in liquidus temperature and an increase in refractive index, and contributes to high dispersion. Therefore, by including Nb ⁵⁺ at a fixed ratio to Ti ⁴⁺ , it is possible to suppress a decrease in glass meltability and an increase in liquidus temperature. Therefore, in the glass according to the present embodiment, the cation ratio [Ti ⁴⁺ / Nb ⁵⁺ ] is preferably in the above range.

Glass according to the 2-1 embodiment, as the network-forming component of glass other than P ₂ O _5, may include _{B 2 O 3, SiO 2,} Al 2 O 3.

In the glass according to the _second embodiment, the upper limit of the content of B ₂ O ₃ is preferably 8.0%, and furthermore, 7.0%, 6.0%, 5.0%, and 4%. 0.0%, 3.0%, 2.0%, and 1.0% are more preferable. The content of B ₂ O ₃ may be 0%.

B ₂ O ₃ is a glass network forming component and has a function of improving the meltability of the glass. On the other hand, when the content of B ₂ O ₃ is large, the decrease in Abbe number is suppressed, the high dispersion is hindered, and the chemical durability tends to decrease. Therefore, from the viewpoint of improving the thermal stability, meltability, moldability, and the like of the glass, the upper limit of the content of B ₂ O ₃ is preferably within the above range.

In the glass according to the 2-1 embodiment, the upper limit of the content of SiO ₂ is preferably 8.0%, and further, 7.0%, 6.0%, 5.0%, and 4.0%. %, 3.5%, 3.0%, 2.5%, 2.0%, 1.5%, 1.0%. The content of SiO ₂ may be 0%.

SiO ₂ is a glass network forming component and has a function of improving the thermal stability, chemical durability, and weather resistance of the glass, increasing the viscosity of the molten glass, and facilitating the molding of the molten glass. On the other hand, when the content of SiO ₂ is large, the meltability of the glass is reduced, and the glass raw material tends to remain undissolved. Therefore, from the viewpoint of improving the meltability of glass, the upper limit of the content of SiO ₂ is preferably within the above range.

In the glass according to the 2-1 embodiment, the upper limit of the content of Al ₂ O ₃ is preferably 5.0%, more preferably 4.0%, 3.5%, 3.0%, 0.5%, 2.0%, 1.5%, 1.0%, and 0.5% are more preferable. The content of Al ₂ O ₃ may be 0%.

Al ₂ O ₃ is a glass component having a function of improving the chemical durability and weather resistance of glass, and can be considered as a network-forming component. On the other hand, when the content of Al ₂ O ₃ increases, the thermal stability of the glass decreases, the glass transition temperature Tg increases, and the meltability tends to decrease. Therefore, the upper limit of the content of Al ₂ O ₃ is preferably within the above range.

In the glass according to the second embodiment, the total content of P ₂ O ₅ , B ₂ O ₃ , SiO ₂ and Al ₂ O ₃ which are network forming components of the glass [P ₂ O ₅ + B ₂ O ₃ + SiO ₂ + Al ₂ O ₃ ] is preferably 45.0%, more preferably 44.0%, 43.0%, 42.0%, 41.0%, 40.0%, and 39.0%. , 38.0%, 37.0%, 36.0%, 35.0%, 34.0%, 33.0%, 32.0%, 31.0%, 30.0%. The lower limit of the total content [P ₂ O ₅ + B ₂ O ₃ + SiO ₂ + Al ₂ O ₃ ] is preferably 10.0%, further 11.0%, 12.0%, 13.0%. %, 14.0%, 15.0%, 16.0%, 17.0%, 18.0%, 19.0%, and 20.0% are more preferable.

When the total content [P ₂ O ₅ + B ₂ O ₃ + SiO ₂ + Al ₂ O ₃ ] is in the above range, the thermal stability of the glass can be improved and the devitrification of the glass can be suppressed.

Further, in the glass according to the _second embodiment, the mass ratio of the content of P ₂ O ₅ to the total content of P ₂ O ₅ , B ₂ O ₃ , SiO ₂ and Al ₂ O ₃ [P ₂ O ₅ / (P ₂ O ₅ + B ₂ O ₃ + SiO ₂ + Al ₂ O ₃ )] is preferably 0.55, more preferably 0.60, 0.65, 0.70, 0.75, 0 .80, 0.85, 0.90 and 0.95 are more preferable. The mass ratio [P ₂ O ₅ / (P ₂ O ₅ + B ₂ O ₃ + SiO ₂ + Al ₂ O ₃ )] can be set to 1.00.

When the mass ratio [P ₂ O ₅ / (P ₂ O ₅ + B ₂ O ₃ + SiO ₂ + Al ₂ O ₃ )] is small, the thermal stability of the glass is lowered and the meltability is also lowered. Therefore, the lower limit of the mass ratio [P ₂ O ₅ / (P ₂ O ₅ + B ₂ O ₃ + SiO ₂ + Al ₂ O ₃ )] is in the above range from the viewpoint of maintaining high dispersion and good melting property of the glass. Preferably, there is.

In the glass according to the _second embodiment, the upper limit of the mass ratio [TiO ₂ / P ₂ O ₅ ] of the content of TiO _{2 and} the content of P ₂ O ₅ is preferably 4.50, and furthermore, Is more preferably 4.00, 3.50, 3.00, 2.50, 2.00, 1.50. The lower limit of the mass ratio [TiO ₂ / P ₂ O ₅ ] is preferably 0.04, and more preferably 0.08, 0.12, 0.16, 0.20, 0.24,. 28, 0.32, 0.36, 0.40, 0.44, 0.48, and 0.52 are more preferable.

In the glass according to the 2-1 embodiment, the inclusion of TiO ₂ promotes the formation of crystals in the glass, causing a problem that the transparency of the glass is reduced (cloudy). This problem can be solved by adding P ₂ O ₅ , which is a network-forming component, to TiO _{2 at} a ratio in the above range.

In addition, in the glass according to the second embodiment, when the content of the glass component is represented by cation%, the cation ratio [Ti ⁴⁺ / P ^5+] between the Ti ⁴⁺ content and the P ⁵⁺ content is ^expressed. Is preferably 1.50, and more preferably 1.40, 1.30, 1.29, 1.28, 1.27, 1.26, 1.25, 1.25, 1.23. , 1.22. The lower limit of the cation ratio [Ti ⁴⁺ / P ⁵⁺ ] is preferably 0.50, and more preferably 0.51, 0.52, and 0.53.

In the glass according to the 2-1 embodiment, by including Ti ⁴⁺ , the generation of crystals in the glass is promoted, and there is a problem that the transparency of the glass is reduced (cloudy). This problem can be solved by adding P ⁵⁺ , which is a network-forming component, to Ti ^{4+ in} a proportion within the above range.

In the glass according to the second embodiment, the upper limit of the content of WO ₃ is preferably 50.0%, further 49.0%, 48.0%, 47.0%, and 46.0%. %, 45.0%, 44.0%, 43.0%, 42.0%, 41.0%, 40.0%, 39.0%, 38.0%, 37.0%, 36.0 %, 35.0%, 34.0%, 33.0%, 32.0%, 31.0%, and 30.0% are more preferable. The lower limit of the content of WO ₃ is preferably 0.01%, and further in the order of 0.1%, 0.3%, 0.5%, 0.7%, 1.0%. preferable. The content of WO ₃ may be 0%.

WO ₃ greatly contributes to high dispersion, but tends to cause coloring of glass as compared with TiO ₂ , Nb ₂ O ₅ and Bi ₂ O _3, and deteriorates transmittance. Therefore, the content of WO ₃ is preferably in the above range.

Further, in the glass according to the second embodiment, when the content of the glass component is represented by cation%, the upper limit of the W ⁶⁺ content is preferably 20.00 cation%, and further 19.00. Cation%, 18.50 cation%, 18.00 cation%, 17.50 cation%, 17.00 cation%, 16.50 cation%, 16.00 cation%, 15.50 cation%, 15.00 cation% , 14.50 cation%, 14.00 cation%, and 13.50 cation%. The lower limit of the content of W ⁶⁺ is preferably 0.40 cation%, more preferably 0.20 cation%, and then 0.10 cation%. The content of W ⁶⁺ may be 0 cation%.

W ⁶⁺ greatly contributes to high dispersion, but tends to cause coloring of the glass as compared with Ti ⁴⁺ , Nb ⁵⁺ and Bi ^3+, and deteriorates transmittance. Therefore, the content of W ⁶⁺ is preferably in the above range.

In the glass according to the _second embodiment, the lower limit of the mass ratio [(TiO ₂ + WO ₃ ) / Nb ₂ O ₅ ] of the total content of TiO ₂ and WO _{3 to} the content of Nb ₂ O ₅ is preferably Is 0.15, and further 0.17, 0.19, 0.20, 0.21, 0.23, 0.25, 0.26, 0.28, 0.30, 0.35, 0.40, 0.45, 0.50, 0.55, 0.56, 0.57, 0.58, 0.59, 0.60, 0.61, 0.62, 0.63,. 64, more preferably 0.65. The upper limit of the mass ratio [(TiO ₂ + WO ₃ ) / Nb ₂ O ₅ ] is preferably 8.00, and 7.90, 7.80, 7.70, 7.60, and 7. 40, 7.20, and 7.00 are more preferable.

By setting the value of the mass ratio [(TiO ₂ + WO ₃ ) / Nb ₂ O ₅ ] in the above range, it is possible to obtain a glass having high dispersion suitable for chromatic aberration correction while suppressing an increase in the refractive index.

In the glass according to the second embodiment, when the content of the glass component is represented by cation%, the cation ratio of the total content of Ti ⁴⁺ and W ^{6+ to} the content of Nb ⁵⁺ [(Ti ⁴⁺ + W ⁶⁺ ) / Nb ⁵⁺ ] is preferably 7.70, more preferably 7.60, 7.50, 7.40, 7.35, 7.30, 7.28, 7 26 is more preferable. The lower limit of the cation ratio [(Ti ⁴⁺ + W ⁶⁺ ) / Nb ⁵⁺ ] is preferably 0.40, and more preferably 0.41 and 0.42.

By setting the value of the cation ratio [(Ti ⁴⁺ + W ⁶⁺ ) / Nb ⁵⁺ ] in the above range, it is possible to obtain a glass having high dispersion suitable for correcting chromatic aberration while suppressing an increase in the refractive index. it can.

In the glass according to the 2-1 embodiment, the upper limit of the content of Na ₂ O is preferably 10.0%, and further, 9.0%, 8.0%, 7.0%, and 6.0%. 0%, 5.0%, 4.0%, and 3.0% are more preferable. The content of Na ₂ O may be 0%.

In the optical glass according to the second embodiment, when the content of the glass component is represented by cation%, the upper limit of the Na ⁺ content is preferably 13.00 cation%, and more preferably 12.00. Cation%, 11.50 cation%, 11.00 cation%, 10.50 cation%, 10.00 cation%, 9.50 cation%, 9.00 cation%, 8.50 cation%, 8.00 cation% Are more preferable. The lower limit of the content of Na ⁺ is preferably 1.50 cation%, further 1.30 cation%, 1.00 cation%, 0.70 cation%, 0.50 cation%, 0.30 cation% Are more preferable. The content of Na ⁺ may be 0 cation%.

In the glass according to the _second embodiment, the upper limit of the content of K ₂ O is preferably 15.0%, and further 14.0%, 13.0%, 12.0%, and 11.2%. 0%, 10.0%, 9.0%, 8.0%, 7.0%, 6.0%, and 5.0% are more preferable. The lower limit of the content of K ₂ O is preferably 0.01%, and more preferably 0.1%, 0.3%, and 0.4%. The content of K ₂ O may be 0%.

In addition, in the optical glass according to the 2-1 embodiment, when the content of the glass component is represented by cation%, the upper limit of the content of K ⁺ is preferably 15.00 cation%, and further 14.50. Cation%, 14.00 cation%, 13.50 cation%, 13.00 cation%, 12.50 cation%, 12.00 cation%, 11.50 cation%, and 11.00 cation% are more preferable in this order. The lower limit of the K ⁺ content is preferably 1.00 cation%, more preferably 0.70 cation%, 0.50 cation%, and 0.30 cation%. The content of K ⁺ may be 0 cation%.

Na ₂ O and K ₂ O, or Na ⁺ and K ⁺ , have the effect of helping to reduce the heat treatment time required to reduce the reduced color due to the highly dispersed components. Among Na ₂ O and K ₂ O, Na ₂ O has a higher effect, and between Na ⁺ and K ⁺ , Na ⁺ has a higher effect. The effect is increased as the content of the glass is increased, but if the content is too large, the thermal stability, chemical durability and weather resistance of the glass are reduced. Therefore, it is preferable that each content of Na ₂ O and K ₂ O, Na ⁺ and K ^{+ be in} the above range.

In the glass according to the _second embodiment, the upper limit of the total content of Li ₂ O, Na ₂ O, and K ₂ O [Li ₂ O + Na ₂ O + K ₂ O] is preferably 20.0%, and furthermore, , 19.0%, 18.0%, 17.0%, 16.0%, 15.0%, 14.0%, 13.0%, 12.0%, 11.0%, 10.0% , 9.0%, 8.0%, 7.0%, and 6.0%. The lower limit of the total content [Li ₂ O + Na ₂ O + K ₂ O] is preferably 0.01%, further 0.02%, 0.03%, 0.04%, 0.05%, 0.06%, 0.07%, 0.08%, 0.09%, 0.10%, 0.20%, 0.30%, 0.40%, and 0.50% are more preferable.

Li ₂ O, Na ₂ O and K ₂ O have a function of shortening the heat treatment time required to reduce the reduction color caused by the high dispersion component and improving the melting property of the glass. However, when these contents increase, the thermal stability, chemical durability and weather resistance of the glass decrease. Therefore, the total content of Li ₂ O, Na ₂ O and K ₂ O [Li ₂ O + Na ₂ O + K ₂ O] is preferably in the above range.

In the optical glass according to the second embodiment, when the content of the glass component is represented by cation%, the upper limit of the total content of Li ⁺ , Na ^+, and K ⁺ [Li ⁺ + Na ⁺ + K ⁺ ] is as follows: It is preferably 22.00 cation%, further 21.00 cation%, 20.00 cation%, 19.00 cation%, 18.00 cation%, 17.00 cation%, 16.50 cation%, 16.60 cation%. 00 cation%, 15.50 cation%, 15.00 cation%, 14.50 cation%, 14.00 cation%, 13.50 cation%, 13.00 cation%, 12.50 cation% 12.00 cation% , And more preferably in the order of 11.50 cation%. The lower limit of the total content [Li ⁺ + Na ⁺ + K ⁺ ] is preferably 1.00 cation%, and more preferably 0.70 cation%, 0.50 cation%, and 0.30 cation%. The total content [Li ⁺ + Na ⁺ + K ⁺ ] may be 0 cation%.

Li ⁺ , Na ⁺ and K ⁺ have the function of shortening the heat treatment time required to reduce the reduction color due to the highly dispersed component, and improving the meltability of the glass. However, when these contents increase, the thermal stability, chemical durability and weather resistance of the glass decrease. Therefore, the total content of Li ⁺ , Na ⁺ and K ⁺ [Li ⁺ + Na ⁺ + K ⁺ ] is preferably in the above range.

In the glass according to the _second embodiment, the mass ratio of the content of Li ₂ O to the total content of Li ₂ O, Na ₂ O, and K ₂ O [Li ₂ O / (Li ₂ O + Na ₂ O + K ₂ O) )] Is preferably 0.0012, more preferably 0.0013, 0.0014, 0.0015, 0.0016, 0.0017, 0.0018, 0.0019, 0.0020, 0. .0021, 0.0022, 0.0023, 0.0024, 0.0025, 0.0026, 0.0027, 0.0028, 0.0029, 0.0030, 0.0032, 0.0035, 0.0037 , 0.0040. The upper limit of the mass ratio [Li ₂ O / (Li ₂ O + Na ₂ O + K ₂ O)] is preferably 1.00, and further, 0.80, 0.60, 0.50, 0.40, and 0.1. It is more preferable in the order of 30, 0.20, 0.18, and 0.16.

In the glass according to the _second embodiment, the upper limit of the content of Rb ₂ O is preferably 5.0%, and more preferably 4.0%, 3.0%, 2.0%, and 1.0%. 0%, 0.7%, 0.5%, 0.3%, and 0.1% are more preferable in this order. Further, the lower limit of the content of Rb ₂ O is preferably 0%. The content of Rb ₂ O may be 0%.

In the glass according to the _second embodiment, the upper limit of the content of Cs ₂ O is preferably 10.0%, and further, 9.0%, 8.0%, 7.0%, and 6.0%. 0%, 5.0%, 4.5%, 4.0%, 3.5%, and 3.0% are more preferable. Further, the lower limit of the content of Cs ₂ O is preferably 0%. The content of Cs ₂ O may be 0%.

Rb ₂ O and Cs ₂ O, like Na ₂ O and K ₂ O, have an effect of helping to shorten the heat treatment time required to reduce the reduction color due to the high dispersion component. It is smaller than Na ₂ O and K ₂ O. In addition, when the content of these elements increases, the thermal stability, chemical durability and weather resistance of the glass decrease. Therefore, it is preferable that each content of Rb ₂ O and Cs ₂ O be in the above range.

  In the glass according to the 2-1 embodiment, the upper limit of the content of MgO is preferably 5.0%, and further, 4.0%, 3.0%, 2.0%, and 1.0%. Are more preferable. Further, the lower limit of the content of MgO is preferably 0%. The content of MgO may be 0%.

  In the glass according to the 2-1 embodiment, the upper limit of the CaO content is preferably 6.0%, and more preferably 5.0%, 4.0%, 3.0%, and 2.0%. , 1.0% more preferably. The lower limit of the CaO content is preferably 0%. The content of CaO may be 0%.

  In the glass according to the 2-1 embodiment, the upper limit of the content of SrO is preferably 7.0%, and further, 6.0%, 5.0%, 4.0%, and 3.0%. , 2.0% and 1.0%. The lower limit of the content of SrO is preferably 0%. The content of SrO may be 0%.

  In the glass according to the second embodiment, the upper limit of the content of BaO is preferably 10.0%, and further, 9.0%, 8.0%, 7.0%, and 6.0%. , 5.0%, 4.0%, 3.0%, 2.0%, 1.0%. Further, the lower limit of the content of BaO is preferably 0%. The content of BaO may be 0%.

  MgO, CaO, SrO, and BaO are all glass components that have the function of improving the thermal stability and fusibility of glass. However, when the content of these glass components is increased, the high dispersibility is impaired, the thermal stability of the glass is reduced, and the glass is easily devitrified. Therefore, the content of each of these glass components is preferably within the above range.

In addition, in the glass according to the 2-1 embodiment, when the content of the glass component is represented by cation%, the upper limit of the Ba ²⁺ content is preferably 10.00 cation%, and further 9.00. Cation%, 8.00 cation%, 7.00 cation%, 6.00 cation%, 5.00 cation%, 4.50 cation%, 4.00 cation%, 3.50 cation%, 3.00 cation% , 2.50 cation%, 2.00 cation%, 1.50 cation%, 1.00 cation%, and 0.70 cation% in this order. Further, the lower limit of the content of Ba ²⁺ is preferably 0 cation%. The content of Ba ²⁺ may be 0 cation%.

Ba ²⁺ is a glass component having a function of improving the thermal stability and the meltability of the glass. However, when the content of these glass components is increased, the high dispersibility is impaired, the thermal stability of the glass is reduced, and the glass is easily devitrified. Therefore, the content of each of these glass components is preferably within the above range.

  In the glass according to the 2-1 embodiment, the upper limit of the total content of MgO, CaO, SrO, and BaO [MgO + CaO + SrO + BaO] is preferably 17. from the viewpoint of maintaining thermal stability without hindering high dispersion. 0%, and further 16.0%, 15.0%, 14.0%, 13.0%, 12.0%, 11.0%, 10.0%, 9.0%, 8.0%. 0%, 7.0%, 6.0%, 5.0%, 4.0%, 3.0%, 2.0%, and 1.0% are more preferable. The lower limit of the total content [MgO + CaO + SrO + BaO] is preferably 0%. The total content [MgO + CaO + SrO + BaO] may be 0%.

In the 2-1 _{embodiment, ZnO, ZrO 2, Ta 2} O 5, Ga 2 O 3, In 2 O 3, Sc 2 O 3, HfO 2, Lu 2 O 3, GeO 2, La 2 O 3, Gd The contents of ₂ O ₃ , Y ₂ O ₃ and Yb ₂ O ₃ can be the same as those in the first embodiment.

The glass according to Embodiment 2-1 mainly includes the above-mentioned glass components, that is, P ₂ O ₅ , B ₂ O ₃ , SiO ₂ , Al ₂ O ₃ , TiO ₂ , Nb ₂ O ₅ , WO ₃ , and Bi ₂ O. _{3, Li 2 O, Na 2} O, K 2 O, Rb 2 O, Cs 2 O, MgO, CaO, SrO, BaO, ZnO, ZrO 2, Ta 2 O 5, Ga 2 O 3, In 2 O 3, It is preferably composed of components selected from Sc ₂ O ₃ , HfO ₂ , Lu ₂ O ₃ , GeO ₂ , La ₂ O ₃ , Gd ₂ O ₃ , Y ₂ O ₃ , and Yb ₂ O _3. Is preferably greater than 95%, more preferably greater than 98%, even more preferably greater than 99%, and even more preferably greater than 99.5%.

  Other glass component compositions in the 2-1 embodiment can be the same as those in the 1-1 embodiment.

(Glass properties)
<Glass transition temperature Tg>
The upper limit of the glass transition temperature Tg of the glass according to Embodiment 2-1 is preferably 750 ° C, and more preferably 740 ° C, 730 ° C, 720 ° C, 710 ° C, and 700 ° C. The lower limit of the glass transition temperature Tg is preferably 500 ° C, and furthermore, 510 ° C, 520 ° C, 530 ° C, 540 ° C, 550 ° C, 560 ° C, 570 ° C, 580 ° C, 590 ° C, 600 ° C, 610 ° C., 620 ° C., and 630 ° C. are more preferable.

  When the upper limit of the glass transition temperature Tg satisfies the above range, an increase in the heat treatment temperature of the glass can be suppressed, and thermal damage to annealing equipment, for example, a continuous annealing furnace called a rare or a batch annealing furnace can be reduced. Further, the power consumption of the furnace can be suppressed.

  When the lower limit of the glass transition temperature Tg satisfies the above range, it becomes easy to maintain the thermal stability of the glass satisfactorily while maintaining the desired Abbe number.

<Refractive index n _d >
In the glass according to the 2-1 embodiment, the upper limit of the refractive index n _{d at} a wavelength of 587.56 nm is preferably 2.1500, and further, 2.1400, 2.1300, 2.200, and 2.1100. , 2.1000, 2.0900, 2.0800, 2.0700, 2.0600, 2.0500, and 2.0400. The lower limit of n _d is preferably 1.8800, and further, 1.8900, 1.9000, 1.9100, 1.9200, 1.9300, 1.9350, 1.9400, 1.9450, A larger value in the order of .9500, 1.9600, 1.9700 is more preferable.

<Refractive index n _C >
In the glass according to the 2-1 embodiment, the upper limit of the refractive index n _{C at} a wavelength of 656.27 nm is preferably 2.1350, and further, 2.1250, 2.1150, 2.1050, and 2.0950. , 2.0850, 2.0750, 2.0650, 2.0550, 2.0450, 2.0350, 2.0250, 2.0150. Further, the lower limit of the refractive index is preferably 1.8650, and further, 1.8750, 1.8850, 1.8950, 1.9050, 1.9150, 1.9200, 1.9250, 1.9350. , 1.9400, 1.9450, and 1.9550 are more preferably larger in this order.

<Light transmittance of glass>
In the 2-1 embodiment, the light transmittance can be evaluated by the coloring degree λ5, as in the 1-1 embodiment.

  In the 2-1 embodiment, the upper limit of λ5 is preferably 460 nm, and more preferably 455 nm, 450 nm, 445 nm, 440 nm, 435 nm, 430 nm, 425 nm, and 420 nm. The standard of the lower limit of λ5 is 360 nm.

<Specific gravity of glass>
The glass according to Embodiment 2-1 is not high in specific gravity while being a highly dispersed glass. Usually, if the specific gravity of the glass can be reduced, the weight of the lens can be reduced. As a result, it is possible to reduce the power consumption of the autofocus driving of the camera lens having the lens. On the other hand, when the specific gravity is excessively reduced, the thermal stability is reduced. Therefore, the upper limit of the specific gravity d is preferably 5.60, and furthermore, 5.50, 5.40, 5.30, 5.20, 5.10, 5.00, 4.90, 4.80. , 4.70, 4.60, 4.50, 4.40, 4.30, 4.20, 4.10, 4.00, 3.90, 3.80, and 3.70 in that order. From the viewpoint of improving thermal stability, the lower limit of the specific gravity d is preferably 2.80, and more preferably 2.90, 3.00, 3.10, and 3.20.

<Liquid phase temperature>
The upper limit of the liquidus temperature of the glass according to Embodiment 2-1 is preferably 1400 ° C., and further 1390 ° C., 1380 ° C., 1370 ° C., 1360 ° C., 1350 ° C., 1340 ° C., 1330 ° C., 1320 ° C. , 1310 ° C, and 1300 ° C. The lower limit of the liquidus temperature is preferably 1000 ° C., and more preferably 1010 ° C., 1020 ° C., 1030 ° C., 1040 ° C., 1050 ° C., 1060 ° C., 1070 ° C., 1080 ° C., 1090 ° C., 1100 ° C., 1110 ° C. C, 1120 C, 1130 C, 1140 C, 1150 C, 1160 C, 1170 C, and 1180 C are more preferable. According to the glass according to the present embodiment, a highly dispersed glass with improved thermal stability of the glass can be obtained.

  The liquidus temperature is determined as follows. 10 cc (10 ml) of glass is put into a platinum crucible, melted at 1250 ° C. to 1350 ° C. for 20 to 30 minutes, cooled to a glass transition temperature Tg or lower, and put together with the platinum crucible into a melting furnace at a predetermined temperature and held for 2 hours. I do. The holding temperature is 1000 ° C. or more, in steps of 5 ° C. or 10 ° C. After holding for 2 hours, the mixture is cooled, and the presence or absence of crystals inside the glass is observed with a 100-fold optical microscope. The lowest temperature at which no crystals are deposited is taken as the liquidus temperature.

(Manufacture of glass)
The glass according to Embodiment 2-1 of the present invention may be prepared by mixing glass raw materials so as to have the above-described predetermined composition and using the prepared glass raw materials according to a known glass manufacturing method. For example, a plurality of types of compounds are prepared and mixed well to form a batch raw material. The batch raw material is put into a melting vessel, melted, refined, and homogenized, then molded into a molten glass, and gradually cooled to obtain a glass. Alternatively, the batch material is placed in a melting vessel and coarsely melted (rough melted). The melt obtained by the coarse melting is rapidly cooled and pulverized to produce a cullet. Further, the cullet is placed in a melting vessel, heated and re-melted (remelted) to obtain a molten glass. After clarification and homogenization, the molten glass is formed and then gradually cooled to obtain a glass. Known methods may be applied to the forming and slow cooling of the molten glass.

  In the production of the glass according to the 2-1 embodiment, the lower limit of the melting temperature during the coarse melting is preferably 1000 ° C. when the batch raw material is roughly melted (rough melted) to produce a cullet. 1050 ° C, 1100 ° C, 1150 ° C, 1200 ° C, 1250, and 1300 ° C are more preferable. The upper limit of the melting temperature is preferably 1500 ° C, and more preferably 1450 ° C, 1400 ° C, and 1350 ° C.

  When the cullet is melted, refined, and molded to produce the glass according to the second embodiment, the lower limit of the melting temperature of the cullet is preferably 1000 ° C., and more preferably 1050 ° C., 1100 ° C., and 1150 ° C. C, 1200 C, 1250, and 1300 C in this order. The upper limit of the melting temperature is preferably 1500 ° C, and more preferably 1450 ° C, 1400 ° C, and 1350 ° C.

  Without passing through the cullet, the lower limit of the melting temperature of the batch raw material is preferably 1000 ° C. when the batch raw material is melted, refined, and molded to produce the glass according to the 2-1 embodiment. 1050 ° C, 1100 ° C, 1150 ° C, 1200 ° C, 1250, and 1300 ° C are more preferable. The upper limit of the melting temperature is preferably 1500 ° C, and more preferably 1450 ° C, 1400 ° C, and 1350 ° C.

  In the production of the glass according to the 2-1 embodiment, the lower limit of the fining temperature when refining the molten glass is preferably 1000 ° C., and more preferably 1050 ° C., 1100 ° C., 1150 ° C., 1200 ° C., 1250 ° C. And 1300 ° C. in this order. The upper limit of the fining temperature is preferably 1500 ° C., and more preferably 1450 ° C., 1400 ° C., and 1350 ° C.

  In the production of the glass according to the 2-1 embodiment, the lower limit of the outflow temperature when the molten glass is poured into the mold is preferably 1000 ° C., and more preferably 1050 ° C., 1100 ° C., 1150 ° C., and 1200 ° C. , 1250 ° C, and 1300 ° C in this order. The upper limit of the outflow temperature is preferably 1500 ° C., and more preferably 1450 ° C., 1400 ° C., and 1350 ° C.

  The compound used when preparing the batch raw material is not particularly limited as long as a desired glass component can be introduced into the glass so as to have a desired content. Such compounds include oxides, orthophosphoric acid, metaphosphate, diphosphorus pentoxide, carbonate, nitrate, hydroxide, fluoride and the like.

(Manufacture of optical glass)
The glass according to Embodiment 2-1 of the present invention can be used as it is as the optical glass according to Embodiment 2-1 of the present invention.

  When the glass according to Embodiment 2-1 of the present invention exhibits a reduction color, the glass according to this embodiment is subjected to a heat treatment to reduce the reduction color, thereby obtaining an optical glass. A known method can be used as the heat treatment method. For example, there is a method in which the glass is heated to a temperature 5 to 20 ° C. lower than the glass transition temperature Tg and held until the coloring is sufficiently reduced. After the heat treatment, the glass can be subjected to annealing to remove the distortion of the glass. As the method of slow cooling, a known method can be used. For example, there is a method of gradually lowering the temperature to a temperature lower by 100 to 150 ° C. than the heating temperature in the heat treatment.

(Manufacture of glass materials for polishing and press molding)
The glass material for polishing and the glass material for press molding according to the 2-1 embodiment of the present invention can be manufactured from any of the glass and the optical glass according to the 2-1 embodiment.

  The polishing glass material is made by subdividing glass or optical glass to produce cut pieces, and if necessary, rough polishing (barrel polishing) each cut piece to equalize the weight and attach a release agent to the surface. It can be easily manufactured by press-forming the reheated and softened glass into a desired shape. Alternatively, in a glass or optical glass manufacturing process, a predetermined weight of molten glass may be separated on a forming die and directly press-formed.

  The glass material for press molding can be manufactured by subdividing glass or optical glass into a predetermined volume, and grinding and polishing the surface. Alternatively, in a manufacturing process of glass or optical glass, a molten glass may be dropped and formed by molding the molten glass droplet.

  In the production of the glass material for polishing and the glass material for press molding, a heat treatment for reducing the reduction color may be performed. The heat treatment method is the same as the heat treatment method in the production of the optical glass. The heat treatment can be performed after molding, or before and after grinding and polishing.

(Manufacture of optical elements, etc.)
The optical element according to Embodiment 2-1 of the present invention can be manufactured from any of the glass, optical glass, glass material for polishing, and glass material for press molding according to Embodiment 2-1 of the present invention.

  The optical element according to Embodiment 2-1 of the present invention can be manufactured by subdividing glass or optical glass into a predetermined volume, and grinding and polishing the surface. In addition, glass or optical glass is subdivided to produce cut pieces, and if necessary, each cut piece is roughly polished (barrel polished) to equalize the weight and make it easier for the release agent to adhere to the surface, It can also be produced by reheating and softening the glass into a shape approximating the shape of the desired optical element, followed by grinding and polishing. Alternatively, in a glass or optical glass manufacturing process, a predetermined weight of molten glass may be separated on a forming die, directly pressed, and finally ground and polished.

  The optical element according to Embodiment 2-1 of the present invention can be manufactured by grinding and polishing the above glass material for polishing. Further, the optical element according to Embodiment 2-1 of the present invention can be manufactured by precision pressing the above glass material for press molding. The glass material for press molding may be manufactured by precision pressing after heating.

  In the manufacture of the optical element according to Embodiment 2-1 of the present invention, a heat treatment for reducing the reduced color may be performed. The heat treatment method is the same as the heat treatment method in the production of the optical glass. The heat treatment can be performed after press molding or precision pressing, and can be performed before or after grinding and polishing.

  In the manufacture of the optical element according to Embodiment 2-1 of the present invention, centering may be performed as necessary.

  The optical function surface of the manufactured optical element can be coated with an antireflection film, a total reflection film, or the like according to the purpose of use.

  Examples of the optical element include various lenses such as an aspheric lens, a micro lens, and a lens array, and a diffraction grating.

2-2 embodiment The glass of the 2-2 embodiment of the present invention is:
Abbe number ν _d is 18.10 or less,
A phosphate glass containing at least one oxide selected from TiO ₂ , Nb ₂ O ₅ , WO ₃ and Bi ₂ O ₃ ,
Under air atmosphere, remelt and mold at a temperature of 110 to 120 ° C. higher than the liquidus temperature LT for 90 minutes,
In an air atmosphere, the glass is kept at a holding temperature of 0 to 20 ° C lower than the glass transition temperature Tg for 15 minutes, and gradually cooled at a cooling rate of 30 ° C / h to a temperature of 120 ° C lower than the holding temperature to obtain a glass having a length of 17 mm and a width of 17 mm. 13mm, 10mm in thickness processed,
In a top view, a portion that is a distance of 0 to 5 mm from a vertical edge and a range of 0 to 5 mm from a horizontal edge is defined as a glass edge,
In a top view, when a portion that is a distance of 6 to 11 mm from a vertical edge and a range of 4 to 9 mm from a horizontal edge is a glass center portion,
When incident light parallel to the thickness direction, the external transmission of the glass edge T _A and the glass center external transmittance T _B is the following formula (2) with a value above T ₁ is calculated at a wavelength of 656nm ,And,
Until the difference between the external transmittance T _B of the external transmittance T _A and the glass center of the glass edge (T _A -T _B) is 5% or less,
Heat treatment in an air atmosphere at a heating rate of 100 ° C./h and holding at a heat treatment temperature of 5 to 15 ° C. lower than the glass transition temperature Tg, and at a cooling rate of 30 ° C./h to a temperature of 120 ° C. lower than the above heat treatment temperature When the slow cooling process of slow cooling is repeated once or multiple times,
A glass in which the total holding time at the heat treatment temperature in the heat treatment is within 48 hours.
T ₁ = 0.83 × ｛1-[(n _C -1) / (n _C +1)] ² ] ² × 98 (2)
(In the formula (2), n _C is the heat treatment until the difference between the external transmittance T _B of the external transmittance T _A and the glass center of the glass edge (T _A -T _B) is less than 5% And the refractive index at a wavelength of 656.27 nm when a slow cooling treatment is performed.)

  Hereinafter, the glass according to Embodiment 2-2 will be described in detail.

In the glass according to Embodiment 2-2, the Abbe number ν _d is 18.10 or less. The upper limit of the Abbe number ν _d is preferably 18.05, and further, 18.00, 17.90, 17.80, 17.70, 17.60, 17.50, 17.40, 17.30. , 17.20, 17.10, 17.00, 16.90, 16.80, 16.78, 16.76, 16.74, 16.72, 16.70, 16.68, 16.66, 16. .64, 16.62, 16.60, 16.58, 16.56, 16.54, 16.52, 16.50. Further, the lower limit of the Abbe number is preferably 15.00, and further, 15.10, 15.20, 15.25, 15.30, 15.35, 15.40, 15.45, 15.50. , 15.52, 15.54, 15.56, 15.58, 15.60.

Glass according to the 2-2 embodiment comprises at least one oxide selected from _{TiO 2, Nb 2 O 5,} WO 3 and Bi ₂ O _3.

The glass according to the second to second embodiments is a phosphate glass. Therefore, the glass according to Embodiment 2-2 mainly contains a phosphate as a network-forming component, and its content is expressed as the content of P ₂ O ₅ .

In the glass according to Embodiment 2-2, the lower limit of the content of P ₂ O ₅ is preferably 7.0%, and further, 8.0%, 9.0%, 10.0%, and 11%. 1.0%, 12.0%, 13.0%, 14.0%, 15.0%, 16.0%, 17.0%, 18.0%, 19.0%, 20.0% Is more preferable. Further, the upper limit of the content of P ₂ O ₅ is preferably 37.0%, and further, 36.0%, 35.0%, 34.5%, 34.0%, 33.5%, 33.0%, 32.5%, 32.0%, 31.5%, 31.0%, 30.5%, and 30.0% are more preferable.

P ₂ O ₅ is a component necessary for glass to contain many highly dispersed components. On the other hand, if P ₂ O ₅ is excessively contained, the meltability deteriorates. Therefore, in the glass according to the present embodiment, the content of P ₂ O ₅ is preferably in the above range.

In the glass according to Embodiment 2-2, when the content of the glass component is represented by cation%, the upper limit of the content of P ⁵⁺ is preferably 42.00 cation%, and further 41.50. Cation%, 41.00 cation%, 40.50 cation%, 40.00 cation%, 39.50 cation%, 39.00 cation%, 38.50 cation%, 38.00 cation%, 37.50 cation% , 37.00 cation%, 36.50 cation%, 36.00 cation%. The lower limit of the content of P ⁵⁺ is preferably 25.00 cation%, more preferably 25.50 cation%, 26.00 cation%, 26.50 cation%, 27.00 cation%, and 27.50 cation%. %, 28.00 cation%, 28.50 cation%, 29.00 cation%, and 29.30 cation% in this order.

P ⁵⁺ is an essential component for suppressing an increase in the refractive index nd and for containing a large amount of highly dispersed components in glass. On the other hand, when P ⁵⁺ is excessively contained, the meltability deteriorates. Therefore, in the optical glass according to the present embodiment, the content of P ⁵⁺ is preferably in the above range.

The glass according to Embodiment 2-2 can relatively uniformly reduce the reduction color caused by highly dispersed components such as TiO ₂ , Nb ₂ O ₅ , WO ₃ and Bi ₂ O ₃ , and reduce the reduction color. This is a glass that can reduce the heat treatment time required for performing the heat treatment. Specifically, when the glass is heat-treated by a predetermined operation, the holding time at the heat treatment temperature (hereinafter, sometimes referred to as “fading time”) is within 48 hours, and the reduced color is reduced to a level that does not cause any problem. It is a glass that can be reduced. Details will be described below.

  In the heat treatment for reducing the reduction color, the fading time until the transmittance of the glass falls within a predetermined range differs depending on the coloring state of the glass and the size of the glass.

  Therefore, in the 2-2nd embodiment, the glass according to the present embodiment is reduced and colored under certain conditions, and the fading time is evaluated using a reduced glass sample processed to a predetermined size. The reduced glass sample used for the measurement is formed by remelting the glass according to the present embodiment at a temperature higher than the liquidus temperature LT by 110 to 120 ° C. for 90 minutes in the air atmosphere, and then forming the glass transition temperature in the air atmosphere. The glass obtained by holding at a holding temperature of 0 to 20 ° C. lower than Tg for 15 minutes and gradually cooling to a temperature of 120 ° C. lower than the holding temperature at a cooling rate of 30 ° C./h is processed into a 17 mm long, 13 mm wide, and 10 mm thick. Get it.

  In order to remelt the glass at a temperature higher by 110 to 120 ° C. than the liquidus temperature LT in the atmosphere, the glass may be placed in a platinum crucible, heated and re-melted (remelted) to obtain a molten glass. At this time, coloring due to the highly dispersed component occurs.

  The molten glass is poured into a mold and formed into a plate shape. This is maintained at a holding temperature of 0 to 20 ° C. lower than the glass transition temperature Tg for 15 minutes in an air atmosphere, and gradually cooled to a temperature of 120 ° C. lower than the holding temperature at a cooling rate of 30 ° C./h to reduce distortion of the glass. remove.

  The glass from which the distortion has been removed is subdivided, polished, and processed into a size of 17 mm long, 13 mm wide and 10 mm thick. At this time, an upper surface and a lower surface (a surface of 17 mm in length and 13 mm in width) are optically polished to obtain a reduced glass sample.

The reduced glass sample thus obtained is subjected to a heat treatment and a slow cooling treatment under the following conditions, and the discoloration time is evaluated.
That is, a heat treatment is performed at a heating rate of 100 ° C./h and maintained at a heat treatment temperature 5 to 15 ° C. lower than the glass transition temperature Tg in an air atmosphere, and at a cooling rate of 30 ° C./h, 120 ° C. lower than the above heat treatment temperature. A slow cooling process for gradually cooling to a temperature is performed. The heat treatment reduces coloring caused by highly dispersed components.

The heat treatment and the slow cooling treatment are performed until the reduced glass sample fades to a level having no practical problem. That is, when the incident light parallel to the thickness direction of the sample after processing, the external transmittance T _B of the external transmittance T _A and glass center portion of the glass edge in the wavelength 656nm is calculated by the following formula (2) that value above T _1, and performed until the difference between the external transmittance T _B of the external transmittance T _a and glass center of the glass end (T _a -T _B) is 5% or less.
T ₁ = 0.83 × {1-{(n _C -1) / (n _C +1)} ² ｝ ² × 98 (2)

Incidentally, n _C in the above formula (2) is heat treated to the difference between the external transmittance T _B of the external transmittance T _A and glass center of the glass end (T _A -T _B) is less than 5% And the refractive index at a wavelength of 656.27 nm when subjected to a slow cooling process. The refractive index n _C is measured based on Japan Optical Glass Industry Association Standard (JOGIS 01-2003).

  The heat treatment and the annealing treatment may be performed once or may be performed plural times. The color fading time in the case where the heat treatment and the annealing treatment are performed a plurality of times may be different for each time.

  In the glass according to Embodiment 2-2, the total fade time in the heat treatment is within 48 hours, preferably within 46 hours, and further within 44 hours, within 42 hours, within 40 hours, within 38 hours, Within 36 hours, within 34 hours, within 32 hours, within 30 hours, within 29 hours, within 28 hours, within 27 hours, within 26 hours, within 25 hours, and more preferably within 24 hours.

  When the heat treatment and the slow cooling treatment are performed once, the color fading time is the bleaching time in one time. When the heat treatment and the slow cooling treatment are performed plural times, the bleaching time in each time is used. Is the sum of For example, if the first color fading time is 12 hours and the second color fading time is 6 hours, the total color fading time is 18 hours.

  In the above heat treatment, the heat treatment temperature is set to a temperature lower by 5 to 15 ° C. than the glass transition temperature Tg in consideration of heat treatment of a plurality of glasses having different glass transition temperatures Tg at a time. Therefore, in the glass according to the present embodiment, if the reduced glass sample obtained as described above is heat-treated at a heat treatment temperature lower by 5 to 15 ° C. than the glass transition temperature Tg, the bleaching time is sufficiently reduced within 48 hours. If the color can be reduced, that is, if the heat treatment is performed at least at a heat treatment temperature lower than the glass transition temperature Tg by 15 ° C., the reduced color can be sufficiently reduced within a bleaching time of 48 hours.

  Here, the glass edge is a portion that is a distance of 0 to 5 mm from a vertical edge and a distance of 0 to 5 mm from a horizontal edge in a top view. This is a portion which is 6 to 11 mm from the vertical end and 4 to 9 mm from the horizontal end when viewed from above.

Heat treatment and slow cooling process, when the incident light parallel to the thickness direction, the external transmittance T _B of the external transmittance T _A and glass center portion of the glass edge at a wavelength of 656 nm, calculated by the above formula (2) performed until a value above T ₁ being. External transmittance T _B of the external transmittance T _A and glass center portion of the glass edge at a wavelength of 656nm is preferably the following formula (3) the value T ₂ or more calculated by, more preferably the following formula (4) in the calculated value T ₃ or more, still more preferably the following equation (5) the value T ₄ or more order calculated by.
T ₂ = 0.84 × ｛1-[(n _C -1) / (n _C +1)] ² ] ² × 98 (3)
T ₃ = 0.85 × ｛1-[(n _C −1) / (n _C +1)] ² ] ² × 98 (4)
T ₄ = 0.86 × ｛1-[(n _C −1) / (n _C +1)] ² ] ² × 98 (5)

Further, the difference between the external transmittance T _B of the external transmittance T _A and glass center of the glass end (T _A -T _B) is 5% or less, the reduction color of the entire glass is substantially uniformly reduced Means that.

In the heat treatment, the reduction of the reduced color of the glass proceeds from the surface of the glass to the center. Therefore, during the heat treatment, the center of the glass is colored deeper than the end of the glass. When the reduced color at the center of the glass is reduced to the same degree as the glass edge, that is, when the reduced color is uniformly reduced, the external transmittance T _A at the glass edge and the external transmittance T at the center of the glass are reduced. The difference from _B (T _A -T _B ) is 5% or less.

2-2 In the glass according to the embodiment, heat treatment and slow cooling process, the difference between the external transmittance T _B of the external transmittance T _A and glass center of the glass end (T _A -T _B) 5% The process is carried out until the content becomes the following, preferably 4% or less, more preferably 3% or less, further preferably 2% or less, further preferably 1% or less, and still more preferably 0.5% or less.

That is, in the glass according to the 2-2 embodiment, heat treatment and slow cooling process, calculates the external transmittance T _B of the external transmittance T _A and glass center portion of the glass edge at a wavelength of 656nm is in the above formula (2) is the is the value above T _1, performed until the difference (T _a -T _B) is 5% or less. Preferably, the heat treatment and slow cooling process is a external transmittance T _A and the external transmittance T _B is the formula (2) the value above T ₁ calculated by the difference (T _A -T _B) is less than 4% Until it becomes 3% or less, 2% or less, 1% or less, and 0.5% or less. The difference (T _A -T _B) are preferred over smaller.

Preferably, in the glass according to the 2-2 embodiment, heat treatment and slow cooling process, the external transmittance T _B is the formula of the external transmittance T _A and glass center portion of the glass edge at a wavelength of 656 nm (3 ) when the value T ₂ or more calculated by, performed until the difference (T _a -T _B) is 5% or less. More preferably, the heat treatment and slow cooling process, the external transmittance T _A and the external transmittance T _B is at the formula (3) the value T ₂ or more calculated by the difference (T _A -T _B) 4% The process is performed until the content becomes 3% or less, 2% or less, 1% or less, and 0.5% or less. The difference (T _A -T _B) are preferred over smaller.

Preferably, the glass according to the 2-2 embodiment, heat treatment and slow cooling process, the external transmittance T _B is the formula of the external transmittance T _A and glass center portion of the glass edge at a wavelength of 656 nm (4) and be calculated value T ₃ or more, performed until the difference (T _a -T _B) is 5% or less. More preferably, the heat treatment and slow cooling process, the external transmittance T _A and the external transmittance T _B is at the formula (4) the value T ₃ or more, which is calculated by the difference (T _A -T _B) 4% The process is performed until the content becomes 3% or less, 2% or less, 1% or less, and 0.5% or less. The difference (T _A -T _B) are preferred over smaller.

Preferably, the glass according to the 2-2 embodiment, heat treatment and slow cooling process, the external transmittance T _B is the formula of the external transmittance T _A and glass center portion of the glass edge at a wavelength of 656nm (5) and be calculated value T ₄ or more, performed until the difference (T _a -T _B) is 5% or less. More preferably, the heat treatment and slow cooling process, the external transmittance T _A and the external transmittance T _B is at the formula (5) the value T ₄ or more, which is calculated by the difference (T _A -T _B) 4% The process is performed until the content becomes 3% or less, 2% or less, 1% or less, and 0.5% or less. The difference (T _A -T _B) are preferred over smaller.

In the glass according to Embodiment 2-2, the shorter the fading time, the better. Thus, a most preferred embodiment, the heat treatment and slow cooling treatment, with fading time within 24 hours, the external transmittance T _B is the formula of the external transmittance T _A and glass center portion of the glass edge at a wavelength of 656 nm (5) in it the calculated values T ₄ or more, the difference (T _a -T _B) is equal to or less than 0.5%.

  The external transmittance is measured based on the Japan Optical Glass Industry Association Standard (JOGIS 02-2003). In the measurement of the external transmittance, the incident light irradiates the upper surface (a surface of 17 mm in length and 13 mm in width) perpendicularly. The incident light is applied so as to fall within the glass edge and glass center regions, that is, within a range of 5 mm × 5 mm.

In the glass according to Embodiment 2-2, the lower limit of the total content of TiO ₂ , Nb ₂ O ₅ , WO ₃ and Bi ₂ O ₃ [TiO ₂ + Nb ₂ O ₅ + WO ₃ + Bi ₂ O ₃ ] is preferably 35%, and further 36%, 38%, 40%, 42%, 44%, 46%, 48%, 50%, 52%, 54%, 56%, 58%, 60%, 62%, More preferred in the order of 64%. The upper limit of the total content [TiO ₂ + Nb ₂ O ₅ + WO ₃ + Bi ₂ O ₃ ] is preferably 90%, and further, 88%, 86%, 85%, 84%, 83%, 82%. , 81%, 80%, 79%, 78%, 77% in this order.

TiO ₂ , Nb ₂ O ₅ , WO ₃ and Bi ₂ O ₃ contribute to high dispersion of glass. Also, by containing an appropriate amount, it also has a function of improving the thermal stability of the glass. Therefore, the lower limit of the total content [TiO ₂ + Nb ₂ O ₅ + WO ₃ + Bi ₂ O ₃ ] is preferably within the above range. On the other hand, TiO ₂ , Nb ₂ O ₅ , WO ₃ and Bi ₂ O ₃ increase the coloring of the glass. Therefore, the upper limit of the total content [TiO ₂ + Nb ₂ O ₅ + WO ₃ + Bi ₂ O ₃ ] is preferably in the above range.

In the glass according to Embodiment 2-2, when the content of the glass component is represented by cation%, the total content of Ti ⁴⁺ , Nb ⁵⁺ , W ⁶⁺ and Bi ³⁺ [Ti ⁴⁺ + Nb ^{5 +} + W ⁶⁺ + Bi ³⁺ ] is preferably 52.00 cation%, more preferably 52.10 cation%, 52.15 cation%, 52.20 cation%, 52.25 cation%, 52.25 cation%. 30 cation% is more preferable. The upper limit of the total content [Ti ⁴⁺ + Nb ⁵⁺ + W ⁶⁺ + Bi ³⁺ ] is preferably 75.00 cation%, more preferably 74.50 cation%, 74.00 cation%, and 73.50 cation%. , 73.00 cation%, 72.50 cation%, 72.00 cation%, 71.50 cation%, 71.00 cation%, and 70.50 cation% in this order.

Ti ⁴⁺ , Nb ⁵⁺ , W ⁶⁺ and Bi ³⁺ contribute to high dispersion of glass. Also, by containing an appropriate amount, it also has a function of improving the thermal stability of the glass. Therefore, the lower limit of the total content [Ti ⁴⁺ + Nb ⁵⁺ + W ⁶⁺ + Bi ³⁺ ] is preferably in the above range. On the other hand, Ti ⁴⁺ , Nb ⁵⁺ , W ⁶⁺ and Bi ³⁺ increase the coloring of the glass. Therefore, the upper limit of the total content [Ti ⁴⁺ + Nb ⁵⁺ + W ⁶⁺ + Bi ³⁺ ] is preferably within the above range.

In the glass according to Embodiment 2-2, the upper limit of the content of Bi ₂ O ₃ is preferably 38%, and furthermore, 35%, 33%, 30%, 28%, 25%, 23%, More preferred in the order of 20%. The lower limit of the content of Bi ₂ O ₃ is preferably 0%. The content of Bi ₂ O ₃ may be 0%.

Bi ₂ O ₃ is a component that contributes to high dispersion. Further, by setting the content of Bi ₂ O ₃ within the above range, an increase in specific gravity and a decrease in glass transition temperature Tg can be suppressed. As the specific gravity of the glass increases, the mass of the optical element increases. For example, when a lens having a large mass is incorporated in an autofocus type imaging lens, the power required for driving the lens during autofocus increases, and the battery is significantly consumed. Therefore, the content of Bi ₂ O ₃ is preferably set in the above range.

In addition, in the glass according to Embodiment 2-2, when the content of the glass component is represented by cation%, the upper limit of the Bi ³⁺ content is preferably 10.00 cation%, and further 9.00. Cation%, 8.00 cation%, 7.00 cation%, 6.00 cation%, 5.00 cation%, 4.50 cation%, 4.00 cation%, 3.50 cation%, 3.00 cation% , 2.50 cation%, 2.00 cation%, 1.50 cation%, and 1.00 cation%. The content of Bi ³⁺ may be 0 cation%.

Bi ³⁺ is a component that contributes to high dispersion. Further, when the content of Bi ³⁺ is in the above range, an increase in specific gravity and a decrease in glass transition temperature Tg can be suppressed. As the specific gravity of the glass increases, the mass of the optical element increases. For example, when a lens having a large mass is incorporated in an autofocus type imaging lens, the power required for driving the lens during autofocus increases, and the battery is significantly consumed. Therefore, the content of Bi ³⁺ is preferably in the above range.

In the glass according to the 2-2 embodiment, the mass ratio of the content and the total content of _{TiO 2, Nb 2 O 5,} WO 3 and Bi ₂ O ₃ of _{Li 2 O [Li 2 O /} (TiO 2 + Nb ₂ O ₅ + WO ₃ + Bi ₂ O ₃ )], and the lower limit of the value obtained by multiplying by 100 is preferably 0.017, more preferably 0.019, 0.021, 0.023, 0.025, 0. 027 and 0.030 are more preferable. The upper limit of the value obtained by multiplying the mass ratio [Li ₂ O / (TiO ₂ + Nb ₂ O ₅ + WO ₃ + Bi ₂ O ₃ )] by 100 is preferably 0.750, more preferably 0.730,0. .710, 0.700, 0.680, 0.650, 0.600, and 0.550 are more preferable.

In the glass according to Embodiment 2-2, when the content of the glass component is represented by cation% and the content of W ⁶⁺ exceeds 0 cation%, the content of Ba ^{2+ and} the content of W ⁶ The upper limit of the cation ratio [Ba ²⁺ / W ⁶⁺ ] to the content of ⁺ is preferably 0.14, and more preferably 0.13, 0.12, 0.11, and 0.10. .

Ba ²⁺ is a component that contributes to low dispersion. Therefore, in the glass according to Embodiment 2-2, the desired high dispersibility can be obtained by ^{incorporating} W ⁶⁺ , which is a highly dispersible component, to the above-mentioned cation ratio with respect to the content of Ba ^2+. Can be maintained.

In the glass according to Embodiment 2-2, when the content of the glass component is represented by cation%, the content of W ⁶⁺ is 0 cation% and the content of Ba ²⁺ is 0 cation. %, The upper limit of the total content of Ti ⁴⁺ and Bi ³⁺ [Ti ⁴⁺ + Bi ³⁺ ] is preferably 35.00 cation%, more preferably 34.00 cation%, and 33.3 cation%. 00 cation%, 32.50 cation%, 32.30 cation%, 32.00 cation%, 31.80 cation%, 31.60 cation%, 31.40 cation%, 31.20 cation%, 31.00 cation %, 30.80 cation%, 30.60 cation%, 30.40 cation%, 30.20 cation%, 30.10 cation%, and 30.00 cation% in this order. The lower limit of the total content [Ti ⁴⁺ + Bi ³⁺ ] is preferably 21.00 cation%, more preferably 21.20 cation%, 21.40 cation%, 21.60 cation%, and 21.80 cation%. 2,2.00 cation%, 22.20 cation%, 22.40 cation%, 22.60 cation%, 22.80 cation%, 23.00 cation%, 23.10 cation%, 23.20 cation%, 23 More preferably, in the order of .30 cation%, 23.40 cation%, and 23.50 cation%.

When the content of W ⁶⁺ is 0 cation% and the content of Ba ²⁺ exceeds 0 cation%, Ti has the largest contribution to high dispersion after W ⁶⁺ among the high dispersion components. ^By setting the total content of ⁴⁺ and Bi ³⁺ having the function of improving thermal stability in the above range, it is possible to suppress the low dispersion by Ba ²⁺ .

  Other glass components in the second embodiment can be the same as those in the second embodiment. Further, the glass properties, glass, optical glass, glass material for polishing, glass material for press molding, optical elements, and the like in the 2-2 embodiment can be the same as those in the 2-1 embodiment.

  Hereinafter, the present invention will be described with reference to examples, but the present invention is not limited to only the following examples.

  Examples 1-1 to 1-3 are examples corresponding to the first embodiment. Examples 2-1 to 2-4 are examples corresponding to the second embodiment.

(Example 1-1)
Nos. Shown in Table 1-1-1, Table 1-1-4, and Table 1-1-5, and Table 1-2-1, Table 1-2-3, and Table 1-2-4. Compound raw materials corresponding to the respective components, that is, raw materials such as phosphates, carbonates, oxides, etc., were weighed and sufficiently mixed to obtain a glass having a composition of 1 to 129, thereby obtaining mixed raw materials.

  Here, Table 1-1-1, Table 1-1-4 and Table 1-1-5 are shown in Table 1-2-1, Table 1-2-3 and Table 1-2-4 by mass%. No. is expressed in cation%. 1 to 129 are shown. That is, the glass composition is shown in Table 1-1-1, Table 1-1-4, and Table 1-1-5, and Table 1-2-1, Table 1-2-3, and Table 1-2-4. Although the method is different, the same No. Have the same composition. Therefore, Table 1-1-1, Table 1-1-4, Table 1-1-5 and Table 1-2-1, Table 1-2-3, and Table 1-2-4 are substantially the same. 4 shows an optical glass.

In Table 1-2-1, Table 1-2-3, and Table 1-2-4, the glass composition is indicated by the cation% when the total amount of the anion component is O ²⁻ . That is, in Table 1-2-1, Table 1-2-3, and Table 1-2-4, the content of O ²⁻ is 100 anion% in all cases.

  Moreover, the total content of the glass components described in Table 1-1-2, Table 1-1-3, and Tables 1-1-6 to 1-1-9 and the ratio between the content of the glass components are as follows. , Table 1-1-1, Table 1-1-4, and Table 1-1-5 are values calculated based on the content of each glass component. Similarly, the total content of the glass components described in Table 1-2-2, Table 1-2-5, and Table 1-2-6 and the ratio between the content of the glass components are shown in Table 1-2. -1, a value calculated based on the content of each glass component described in Table 1-2-3 and Table 1-2-4.

  The above prepared raw material was put into a platinum crucible, heated to 1200 ° C. to 1350 ° C., melted, stirred and clarified, and then the molten glass was cast from the crucible into a mold to form a glass block.

  Observation of each of the obtained glass blocks revealed no foreign matter such as crystals or unmelted raw materials in the glass, and high-quality optical glass with high homogeneity was obtained. In addition, optical glass No. Nos. 1 to 6 and 12 to 129 are examples of the 1-1 embodiment, and optical glass Nos. 1 to 129 are examples of the 1-2 embodiment.

  The obtained optical glass No. The refractive index nd, Abbe number νd, glass transition temperature, specific gravity, λ5, and liquid phase temperature of 1 to 129 are shown in Tables 1-3, 1-4-1 and 1-4-4-2. The refractive index nd, Abbe number νd, glass transition temperature, specific gravity, λ5, and liquidus temperature were measured as follows. In addition, the blank in Table 1-3 shows that it has not been measured.

(1) Refractive index nd and Abbe number νd
It was measured based on Japan Optical Glass Industry Association standard JOGIS-01. The measurement results are shown in Table 1-3, Table 1-4-1 and Table 1-4-2.

(2) Glass transition temperature Tg
The glass transition temperature was measured using a differential scanning calorimeter DSC8270 from an endothermic curve when the temperature of the solid-state glass was raised. The Tg using this measurement shows a correspondence with the Tg measured based on JOGIS-08, Japan Optical Glass Industry Association Standard. The measurement results are shown in Table 1-3, Table 1-4-1 and Table 1-4-2.

(3) λ5
λ5 was measured as follows. Spectral transmittance in a wavelength range from 280 nm to 700 nm was measured using a glass sample having a thickness of 10 mm and having parallel and optically polished flat surfaces. The spectral transmittance was calculated by B / A by injecting a light beam of intensity A perpendicularly to one optically polished plane and measuring the intensity B of a light beam emitted from the other plane. Therefore, the spectral transmittance includes the reflection loss of light rays on the sample surface. The wavelength at which the spectral transmittance becomes 5% is λ5. The measurement results are shown in Table 1-3, Table 1-4-1 and Table 1-4-2.

(4) Specific Gravity The specific gravity was measured based on Japan Optical Glass Industry Association Standard JOGIS-05. The measurement results are shown in Table 1-3, Table 1-4-1 and Table 1-4-2.

(5) Liquid phase temperature LT
The glass sample was placed in a furnace heated to a predetermined temperature and held for 2 hours. After cooling, the inside of the glass was observed with an optical microscope of 100 times, and the liquidus temperature was determined from the presence or absence of crystals. The measurement results are shown in Table 1-3, Table 1-4-1 and Table 1-4-2.

(Example 1-2)
In the same manner as in Example 1-1, optical glass no. The glass raw material was heated, melted, clarified, and homogenized to obtain 1-129, and the obtained molten glass was poured into a mold, rapidly cooled, and formed into a glass block. Next, after annealing the glass block, it was cut and ground to produce a glass material for press molding.

(Example 1-3)
The glass material for press molding made of various optical glasses produced in Example 1-2 is heated and softened, and press-molded by a known method using a press mold to produce optical element blanks such as lens blanks and prism blanks. did.

  The optical element blank was precisely annealed to precisely adjust the refractive index to a required refractive index, and then a concave lens, a convex lens, and a prism were manufactured by a known grinding and polishing method.

  When the obtained lens and a lens made of a low dispersion glass having a large Abbe number νd were combined, chromatic aberration could be corrected well and the field curvature could be reduced.

  The following Examples 2-1 and 2-2 are examples corresponding to the 2-1 embodiment, and Examples 2-3 and 2-4 are examples corresponding to the 2-2 embodiment.

  Here, in Example 2-1, Table 2-1A shows the glass compositions of the glass samples A to D by mass%, and Table 2-1B shows the cation%. That is, although the display method of the glass composition is different between Table 2-1A and Table 2-1B, the glasses with the same number have the same composition. Thus, Tables 2-1A and 2-1B show substantially the same glass.

  Similarly, in Example 2-2, the glass samples in Tables 2-3A-1 to 2-3A-8 are shown by mass%, and Tables 2-3B-1 to 2-3B-8 are shown in cation%. The glass compositions of Nos. 1 to 109 are indicated. That is, although the display method of the glass composition is different between Tables 2-3A-1 to 2-3A-8 and Tables 2-3B-1 to 2-3B-8, the glasses having the same number have the same composition. Therefore, Tables 2-3A-1 to 2-3A-8 and Tables 2-3B-1 to 2-3B-8 show substantially the same glass.

In Table 2-1B and Tables 2-3B-1 to 2-3B-8, the glass composition is indicated by cation% when the total amount of the anion component is O ²⁻ . That is, in Table 2-1B and Tables 2-3B-1 to 2-3B-8, the content of O ²⁻ is 100 anion% in all cases.

(Example 2-1)
[Preparation of glass sample]
Raw materials are weighed and blended so that the composition of the obtained glass becomes each of the compositions shown in Table 2-1A and Table 2-1B, and the obtained blended raw material (batch raw material) is put into a platinum crucible, and then stored at 1300 to 1300. The mixture was heated and melted at 1350 ° C. for 90 minutes in an air atmosphere, and homogenized and refined by stirring to obtain a molten glass. The molten glass was cast into a mold, molded, gradually cooled, ground and polished to a length of 17 mm, a width of 12 mm, and a thickness of 10 mm to obtain a glass sample. At this time, the upper surface and the lower surface (a surface having a length of 17 mm and a width of 12 mm) were optically polished.
The obtained glass sample had a reduced color.

[Evaluation of glass sample]
The obtained glass samples, by the method described below, confirmation of the glass composition, refractive index (n _d and n _C), Abbe number ([nu _d), glass transition temperature (Tg), the liquidus temperature (LT), The value of βOH was measured, and the retention time at the heat treatment temperature required to sufficiently reduce the reduced color and the transmittance after the heat treatment were measured.

[1] The glass samples obtained as confirmation of the glass composition described above a suitable amount collected, which was acid and alkali treatment, the Li ₂ O content was determined by ICP-MS, glass other than Li ₂ O The content of the component was measured by ICP-AES, and it was confirmed that the content was consistent with each oxide composition shown in Table 2-1A and Table 2-1B.

[2] the refractive index (n _d and n _C), Abbe number ([nu _d)
The glass sample was kept at a temperature near the glass transition temperature Tg for 48 hours in an air atmosphere, then gradually cooled at a temperature lowering rate of 30 ° C./hour, and then allowed to cool to reduce coloring. The obtained sample was processed to produce a prism, and the refractive indices n _d , n _F , and n _C were measured based on the refractive index measurement method of the Japan Optical Glass Industrial Standards. The Abbe number ν _d was calculated using the measured values of the refractive indexes n _d , n _F , and n _C. The results are shown in Table 2-1A.

[3] Glass transition temperature (Tg)
The measurement was performed at a heating rate of 10 ° C./min using a thermomechanical analyzer manufactured by Rigaku Corporation. The results are shown in Table 2-1A.

[4] Liquid phase temperature A glass sample of 10 cc (10 ml) was put into a platinum crucible, melted at 1250 ° C. to 1350 ° C. for 20 to 30 minutes, cooled to a glass transition temperature Tg or lower, and the glass was cooled together with the platinum crucible at a predetermined temperature. It was put in the melting furnace and kept for 2 hours. The holding temperature was 1000 ° C. or higher in steps of 10 ° C. The lowest temperature at which no crystal was precipitated after holding for 2 hours was taken as the liquidus temperature. The results are shown in Table 2-1A.

[5] βOH
The glass sample was processed into a 1 mm-thick plate that was optically polished on both sides parallel and flat. Light is incident on the optical polished surface in a perpendicular direction, and the external transmittance C at a wavelength of 2500 nm and the external transmittance D at a wavelength of 2900 nm are measured using a spectrophotometer (UV-3100, manufactured by Shimadzu). ΒOH was calculated by the equation (1).
βOH = − [ln (D / C)] / t (1)
In the above formula (1), ln is a natural logarithm, and the thickness t corresponds to the interval between the two planes. The results are shown in Table 2-1A.

[6] Holding Time at Heat Treatment Temperature The above glass sample exhibiting a reduced color was heat treated. That is, in an air atmosphere, heating is performed at a heating rate of 100 ° C./hour, a heat treatment is performed at a heating temperature of 5 to 15 ° C. lower than the glass transition temperature Tg for a predetermined time, and a cooling rate of 30 ° C./hour is performed at 120 ° C. It was gradually cooled to a low temperature. The heat treatment and slow cooling were repeated until the reduced color of the glass sample was sufficiently reduced. When the reduced color was reduced and the color became uniform, it was evaluated that the reduced color was sufficiently reduced. Table 2-2 shows the total holding time at the heat treatment temperature required for sufficiently reducing the reduced color.

[7] Transmittance after heat treatment The external transmittance of the glass sample in which the reduced color was reduced by the heat treatment and the color became uniform was measured. Light was incident in a direction perpendicular to the optically polished surface, and the external transmittance at a wavelength of 656 nm was measured using a spectrophotometer (UV-3150, manufactured by Shimadzu). The results are shown in Table 2-2.

(Example 2-2)
[Preparation of glass sample]
A glass sample was prepared in the same manner as in Example 2-1 except that the composition of the obtained glass was adjusted to each of the compositions shown in Table 3 and steam was added to the melting atmosphere to obtain a molten glass.
The obtained glass sample had a reduced color.

[Evaluation of glass sample]
The obtained glass samples, in the same manner as in Example 2-1, confirmation of the glass composition, refractive index (n _d and n _C), Abbe number ([nu _d), glass transition temperature (Tg), the liquidus temperature (LT) and the value of βOH were measured, and the retention time at the heat treatment temperature required for sufficiently reducing the reduced color and the transmittance after the heat treatment were measured. The results are shown in Tables 2-3A and 2-3B and 2-4.

(Example 2-3)
[Preparation of reduced glass sample]
The glass samples (Samples A to D) obtained in Example 2-1 were heated at 1300 ° C. for 90 minutes in an air atmosphere to be remelted, homogenized and clarified by stirring to obtain a molten glass. The molten glass is cast into a mold and molded, and is kept at a holding temperature of 0 to 20 ° C lower than the glass transition temperature Tg for 15 minutes in an air atmosphere, and at a cooling rate of 30 ° C / h, 120 ° C above the holding temperature. The glass was gradually cooled to a low temperature, ground and polished to a length of 17 mm, a width of 12 mm, and a thickness of 10 mm to obtain a reduced glass sample. At this time, the upper surface and the lower surface (a surface having a length of 17 mm and a width of 12 mm) were optically polished.
The obtained reduced glass sample had a reduced color.

[Evaluation of reduced glass samples]
The obtained reduced glass sample was heated at a heating rate of 100 ° C./hour under an air atmosphere, and heat-treated for a predetermined time at a heating temperature of 5 to 15 ° C. lower than the glass transition temperature Tg, and at a cooling rate of 30 ° C./hour. A slow cooling treatment was performed to a temperature 120 ° C. lower than the heat treatment temperature. Until the difference between the external transmittance T _B of the external transmittance T _A and glass center of the glass end (T _A -T _B) is 5% or less, was repeated heat treatment and slow cooling process. The external transmittances T _A and T _B were measured by using a spectrophotometer (UV-3150, manufactured by Shimadzu) to measure the external transmittance at a wavelength of 656 nm by irradiating light in a direction perpendicular to the optically polished surface. .

Total and external transmission of holding time at the heat treatment temperature difference between the external transmittance T _B of the external transmittance T _A and glass center of the glass end (T _A -T _B) is required until more than 5% the rate T _a and T _B are shown in Table 2-5.

(Example 2-4)
[Preparation of reduced glass sample]
The glass samples (sample Nos. 1 to 20, 22 to 32, 42, 44 to 52, 54, 57 to 80, 88 to 95) obtained in Example 2-2 were prepared in the same manner as in Example 2-3. Remelting was performed to obtain a reduced glass sample.
The obtained reduced glass sample had a reduced color.

[Evaluation of reduced glass samples]
The resultant reducing glass samples, in the same manner as in Example 2-3, the difference between the external transmittance T _B of the external transmittance T _A and glass center of the glass end (T _A -T _B) is 5 %, And the total of the holding times at the heat treatment temperature required until the content becomes not more than% and the external transmittances T _A and T _B were measured. The results are shown in Table 2-6.

Claims (6)

Abbe number νd is 16.70 or less,
The refractive index nd is 2.1000 or less,
P ₂ O ₅ , TiO ₂ and Nb ₂ O ₅ ,
Mass ratio of the content of content and Nb ₂ O ₅ of _{TiO 2 [TiO 2 / Nb 2} O 5] is not less than 0.15,
The total content of TiO ₂ , Nb ₂ O ₅ , WO ₃ and Bi ₂ O ₃ [TiO ₂ + Nb ₂ O ₅ + WO ₃ + Bi ₂ O ₃ ] is 63.0% by mass or more;
The total content of TiO ₂ , Nb ₂ O ₅ and WO ₃ [TiO ₂ + Nb ₂ O ₅ + WO ₃ ] is 45.0 mass% or more;
A phosphate optical glass having a Na ₂ O content of 2.69% by mass or less. The phosphate optical glass according to claim 1, wherein the content of Bi ₂ O ₃ is 29.0% by mass or less. Abbe number νd is 16.70 or less,
The content of Bi ₂ O ₃ is 29.0% by mass or less,
The total content of TiO ₂ , Nb ₂ O ₅ and WO ₃ is 45.0% by mass or more;
The total content of TiO ₂ , Nb ₂ O ₅ , WO ₃ and Bi ₂ O ₃ [TiO ₂ + Nb ₂ O ₅ + WO ₃ + Bi ₂ O ₃ ] is 63.0% by mass or more;
A phosphate optical glass having a Na ₂ O content of 2.69 % by mass or less. The mass ratio of the total content of TiO ₂ and WO _{3 to} the content of Nb ₂ O ₅ [(TiO ₂ + WO ₃ ) / Nb ₂ O ₅ ] is 0.15 or more. 3. The phosphate optical glass according to item 1.   A press-molding glass material comprising the phosphate optical glass according to claim 1.   An optical element comprising the phosphate optical glass according to claim 1.