JP5808081B2 - Optical glass, optical element and preform - Google Patents

Description

  The present invention relates to an optical glass, an optical element, and a preform.

High refractive index and high dispersion glass is in great demand as a material for optical elements such as various lenses. For example, in Patent Documents 1 to 3, the refractive index (n _d ) is 1.70 to 2.00, the Abbe number ( An optical glass with a ν _d ) of 15 to 29.5 is described.

  An optical system in which these optical glasses are used is mounted on an optical product such as a digital camera. However, in order to improve chromatic aberration, it is desirable that the optical glass in the high refractive index and high dispersion region has a small partial dispersion ratio.

  Conventionally, high refractive index and high dispersion glass has a tendency to deteriorate the light transmittance (coloring degree) in the visible region.

JP-A-52-25812 JP 2004-161598 A International Publication No. 2004/110942 Pamphlet

In optical glass, there is an approximately linear relationship between a partial dispersion ratio (θg, F) representing partial dispersion in a short wavelength region and an Abbe number (ν _d ). The straight line representing this relationship plots the partial dispersion ratio and Abbe number of NSL7 and PBM2 on the Cartesian coordinates employing the partial dispersion ratio (θg, F) on the vertical axis and the Abbe number (ν _d ) on the horizontal axis. It is represented by a straight line connecting two points and is called a normal line (see FIG. 1). Normal glass, which is the standard for normal lines, differs depending on the optical glass manufacturer, but each company defines it with almost the same slope and intercept. (NSL7 and PBM2 are optical glasses manufactured by OHARA, Inc., and the Abbe number (ν _d ) of PBM2 is 36.3, the partial dispersion ratio (θg, F) is 0.5828, and the Abbe number (ν _d ) of NSL7. Is 60.5, and the partial dispersion ratio (θg, F) is 0.5436.)

However, particularly high dispersion (low Abbe number (ν _d )) glass has a partial dispersion ratio (θg, F) of the glass that is far from the normal line. Therefore, when an optical element is manufactured using these highly dispersed glasses, chromatic aberration is generated in the optical element, so that it is necessary to correct the chromatic aberration.

An object of the present invention is to solve the problems in the conventional optical glass as described above.
That is, an object of the present invention is to provide an optical glass having a high refractive index and a high dispersibility, a small partial dispersion ratio, and a good transmittance.

The inventor has intensively studied to solve the above-mentioned problems, and has completed the present invention.
The present invention includes the following (1) to (9).
(1) the glass the total amount of substance of the oxide composition in terms of, 10.0 to 60.0% of _P 2 _{O 5} component in mol%, and _Nb 2 _{O 5} component 5.0-45.0%, The content of TiO ₂ component is 0 to 30.0%, the content of B ₂ O ₃ component is 0% or more and less than 5.0%, and the partial dispersion ratio (θg, F) is between the Abbe number (ν _d ) and ν _d In the range of ≦ 25, the relationship of (−0.0016 × ν _d +0.63460) ≦ (θg, F) ≦ (−0.00563 × ν _d +0.75873) is satisfied, and in the range of ν _d > 25 (− 0.0025 × ν _d +0.65710) ≦ (θg, F) ≦ −0.0034 × ν _d +0.70300
(2) The optical glass according to the above (1), wherein a substance amount ratio TiO ₂ / Nb ₂ O ₅ having an oxide equivalent composition is 1.00 or less.
(3) the glass the total amount of substance of the oxide composition in terms of the following 8.9% of WO ₃ components in mole%, and Bi ₂ O ₃ component from the above (1) containing less 13.9% (2 ) Any one of the optical glasses.
(4) SiO ₂ component 0 to 30.0% in mol% with respect to the total amount of glass in oxide-converted composition
GeO ₂ component 0 to 20.0%
TeO ₂ component 0 to 20.0%
Li ₂ O component 0 to 30.0%
Na ₂ O component 0-50.0%
K ₂ O component 0 to 25.0%
Cs ₂ O component 0 to 20.0%
MgO component 0 to 15.0%
CaO component 0 to 20.0%
SrO component 0 to 20.0%
BaO component 0 to 30.0%
ZnO component 0 to 30.0%
Al ₂ O ₃ component 0 to 20.0%
ZrO ₂ component 0 to 20.0%
La ₂ O ₃ component 0 to 20.0%
Gd ₂ O ₃ component 0 to 20.0%
Y ₂ O ₃ component 0 to 20.0%
Ta ₂ O ₅ component 0 to 20.0%
In ₂ O ₃ component 0 to 20.0%
Yb ₂ O ₃ component 0 to 20.0%
CeO ₂ component 0-1.0%
Sb ₂ O ₃ component 0 to 1.0%
Optical glass in any one of said (1)-(3) which further contains each component of.
(5) The optical glass according to any one of the above (1) to (4), wherein the substance amount ratio (Li ₂ O + K ₂ O) / Na ₂ O of the oxide equivalent composition is 2.000 or less.
(6) A wavelength having a refractive index (n _d ) of 1.70 or more and 2.00 or less, an Abbe number (ν _d ) of 15 or more and 29.5 or less, and a spectral transmittance of 70% (λ ₇₀ ) Optical glass in any one of said (1)-(5) whose is 500 nm or less.
(7) An optical element obtained by grinding and polishing the optical glass according to any one of (1) to (6).
(8) An optical element obtained by precision press-molding the optical glass according to any one of (1) to (7).
(9) Preform for precision press molding comprising the optical glass according to any one of (1) to (8).

  According to the present invention, an optical glass having a high refractive index and a high dispersibility, a small partial dispersion ratio, and a good transmittance can be provided.

It is a figure which shows the normal line by which partial dispersion ratio ((theta) g, F) is represented on the orthogonal coordinate of a vertical axis | shaft and Abbe number ((nu) _d ) on a horizontal axis. It is a figure which shows the relationship between the partial dispersion ratio ((theta) g, F) and the Abbe number ((nu) _d ) about the glass of the Example of this application, and a comparative example.

The present invention will be described.
The present invention, the glass the total amount of substance of the oxide composition in terms of, in mole percent, from 10.0 to 60.0% of P ₂ O ₅ component, a Nb ₂ O ₅ component 5.0 to 45.0% TiO ₂ component is contained in an amount of 0 to 30.0%, B ₂ O ₃ component is contained in an amount of 0% or more and less than 5.0%, and the partial dispersion ratio (θg, F) is between the Abbe number (ν _d ) and ν _The optical glass satisfies the relationship of the following formula (1) in the range of _d ≦ 25, and satisfies the relationship of the following formula (2) in the range of ν _d > 25.
Formula (1) ... (− 0.0016 × ν _d +0.63460) ≦ (θg, F) ≦ (−0.00563 × ν _d +0.75873)
Formula (2) ... (− 0.0025 × ν _d +0.65710) ≦ (θg, F) ≦ (−0.0034 × ν _d +0.70300)
Hereinafter, such an optical glass is also referred to as “optical glass of the present invention”.

Each component of the optical glass of the present invention will be described.
Hereinafter, unless otherwise specified, the content (%) of each component means mol% based on oxide.

The P ₂ O ₅ component is an important component as a glass-forming oxide and an effective component for imparting high dispersibility to the glass. Accordingly, the P ₂ O ₅ component can preferably be contained at a lower limit of 10.0%, more preferably 15.0%, still more preferably 20.0%, preferably 60.0%, more preferably 50%. 0.0%, more preferably 40.0% can be contained as the upper limit.
The P ₂ O ₅ component can be contained in the glass using, for example, orthophosphoric acid, phosphate, or the like as a raw material.

The Nb ₂ O ₅ component is an essential component effective for increasing the refractive index, decreasing the partial dispersion ratio while increasing the dispersion, and improving the chemical durability and devitrification resistance. However, if the amount is too small, the effect becomes insufficient. On the other hand, if the amount is too large, the devitrification resistance is deteriorated, and the transmittance in the visible light short wavelength region is likely to be deteriorated. Therefore, it can be contained preferably at a lower limit of 5.0%, more preferably 10.0%, still more preferably 15.0%, preferably 45.0%, more preferably 40.0%, still more preferably May contain up to 35.0%.
The Nb ₂ O ₅ component can be contained in the glass using, for example, Nb ₂ O ₅ as a raw material.

The TiO ₂ component has the effect of increasing the partial dispersion ratio while increasing the refractive index and increasing the dispersion. However, if the amount is too large, the transmittance in the visible light short wavelength region is deteriorated. Accordingly, the upper limit of the amount of this component is preferably 30.0%, more preferably 26.0%, still more preferably 15.0%, and most preferably 12%.
The TiO ₂ component can be contained in the glass using, for example, TiO ₂ as a raw material.

The B ₂ O ₃ component is an optional component that acts as a glass-forming oxide and is effective in lowering the glass transition point (Tg). However, if the amount is too large, chemical durability tends to deteriorate. Accordingly, the upper limit of the amount of this component is preferably less than 5%, more preferably 3.0%, and still more preferably less than 2.37%.
B ₂ O ₃ can be contained in the glass using, for example, H ₃ BO ₃ or B ₂ O ₃ as a raw material.

In the optical glass of the present invention, the substance amount ratio of TiO ₂ and Nb ₂ O ₅ is preferably 1.00 or less. The partial dispersion ratio (θg, F) can be reduced by setting the substance amount ratio to 1.00 or less. In addition, the transparency of the glass in the visible range can be increased, and the coloring of the glass can be reduced. Therefore, the substance amount ratio TiO ₂ / Nb ₂ O _{5 with} respect to the total amount of glass in the oxide conversion composition is preferably 1.00%, more preferably 0.80%, and even more preferably 0.63%. can do.

The WO ₃ component has the effect of adjusting the optical constant, improving devitrification resistance, and increasing the partial dispersion ratio. However, if the amount is too large, the devitrification resistance and the light transmittance in the short wavelength region of the visible light region are adversely affected. Accordingly, the upper limit of the amount of this component is preferably 8.9%, more preferably 5.5%, and still more preferably less than 1.9%.
The WO ₃ component can be contained in the glass using, for example, WO ₃ as a raw material.

The Bi ₂ O ₃ component has the effect of increasing the refractive index, increasing the dispersion, reducing the partial dispersion ratio, and lowering the glass transition temperature (Tg). However, if the amount is too large, the devitrification resistance tends to deteriorate, and the partial dispersion ratio tends to increase. Therefore, the upper limit of the amount of this component is preferably 13.9%, more preferably 11%, and still more preferably 9%. In addition, since Bi ₂ O ₃ is an optional component, it is possible to produce the glass of the present invention even if it is not contained, but in order to facilitate the above effect, it preferably exceeds 0%, more The lower limit is preferably 0.1%, more preferably 1.0%.
The Bi ₂ O ₃ component can be contained in the glass using, for example, Bi ₂ O ₃ as a raw material.

The SiO ₂ component is an optional component that acts as a glass-forming oxide, and is effective in increasing the viscosity of the glass and improving devitrification resistance and chemical durability. However, if the amount is too small, the effect is insufficient. On the other hand, if the amount is too large, the devitrification resistance and the meltability tend to deteriorate. Therefore, the upper limit of the amount of this component is preferably 30.0%, more preferably 25.0%, and still more preferably 20.0%.
The SiO ₂ component can be contained in the glass using, for example, SiO ₂ as a raw material.

The GeO ₂ component is an optional component having an effect of increasing the refractive index and improving the devitrification resistance, and acts as a glass forming oxide. However, if the amount is too large, the raw material is very expensive, which increases the cost. Accordingly, the upper limit is preferably 20.0%, more preferably 15.0%, and still more preferably 8.5%.
The GeO ₂ component can be contained in the glass using, for example, GeO ₂ as a raw material.

The TeO ₂ component is a component that has an effect of increasing the refractive index. When melting a glass raw material in a platinum crucible or a melting tank in which a portion in contact with molten glass is formed of platinum, tellurium and platinum are alloyed. Since the heat resistance is likely to deteriorate in the alloyed part, there is a concern about the risk of an accident that a hole is opened in the part and the molten glass flows out. Therefore, the upper limit is preferably 20.0%, more preferably 15.0%, and still more preferably 7.6%.
The TeO ₂ component can be contained in the glass using, for example, TeO ₂ as a raw material.

The Li ₂ O component has the effect of reducing the partial dispersion ratio, significantly lowering the glass transition temperature (Tg), and promoting the melting of the mixed glass raw material. In the composition system of the present invention, the reheat press molding is effective. There is an effect to suppress devitrification. However, if the amount is too large, the devitrification resistance tends to deteriorate rapidly. Accordingly, the upper limit of the amount of this component should preferably be 30.0%, more preferably 25.0%, still more preferably less than 17.0%. In addition, since Li ₂ O is an optional component, it is possible to produce the glass of the present invention even if it is not contained. However, in order to facilitate the above effect, it preferably exceeds 0%, more preferably Is 0.1%, more preferably 1.0%.
The Li ₂ O component can be contained in the glass using, for example, Li ₂ O or a carbonate, nitrate, hydroxide, or the like as a raw material.

The Na ₂ O component has the effect of lowering the glass transition temperature (Tg) and promoting the melting of the mixed glass raw material. However, if the amount is too large, the devitrification resistance tends to deteriorate rapidly. Accordingly, the upper limit of the amount of this component is preferably 50.0%, more preferably 45.0%, and still more preferably 40.0%. In addition, since Na ₂ O is an optional component, it is possible to produce the glass of the present invention even if it is not contained. However, in order to easily exhibit the effect, it preferably exceeds 0%, more preferably Is 0.1%, more preferably 1.0%, and most preferably 13%.
The Na ₂ O component can be contained in the glass by using, for example, Na ₂ O or its carbonate, nitrate, hydroxide, etc. as a raw material.

The K ₂ O component has the effect of lowering the glass transition temperature (Tg) and promoting the melting of the mixed glass raw material. However, when the amount is too large, the devitrification resistance deteriorates rapidly, and in the composition system of the present invention, the devitrification property at the time of reheat press molding tends to deteriorate rapidly. Therefore, the upper limit of the amount of this component should preferably be 25.0%, more preferably 20.0%, still more preferably 18.0%, and most preferably 13%.
The K ₂ O component can be contained in the glass using, for example, K ₂ O or a carbonate, nitrate, hydroxide, or the like as a raw material.

The Cs ₂ O component has an effect of lowering the glass transition temperature (Tg) and promoting the melting of the mixed glass raw material. Therefore, the upper limit is preferably 20.0%, more preferably 19.0%, and still more preferably 18.0%.
Cs ₂ O component, the raw material as for example Cs ₂ O or a carbonate, nitrate, hydroxide and the like can be contained in the glass by using.

The MgO component is effective for adjusting the optical constant. However, if the amount is too large, the devitrification resistance tends to deteriorate. Therefore, the upper limit is preferably 15.0%, more preferably 14.0%, and still more preferably 13.0%.
The MgO component can be contained in the glass using, for example, MgO or a carbonate, nitrate, hydroxide, or the like as a raw material.

The CaO component is effective for adjusting the optical constant. However, if the amount is too large, the devitrification resistance tends to deteriorate. Therefore, the upper limit is preferably 20.0%, more preferably 19.5%, and still more preferably 19.0%.
The CaO component can be contained in the glass using, for example, CaO or a carbonate, nitrate, hydroxide, or the like as a raw material.

The SrO component is effective for adjusting the optical constant. However, if the amount is too large, the devitrification resistance tends to deteriorate. Therefore, the upper limit is preferably 20.0%, more preferably 19.5%, and still more preferably 19.0%.
The SrO component can be contained in the glass using, for example, SrO or a carbonate, nitrate, hydroxide, or the like as a raw material.

The BaO component is effective for adjusting the optical constant. However, if the amount is too large, the devitrification resistance tends to deteriorate. Therefore, the upper limit of the amount of this component is preferably 30.0%, more preferably 25.0%, and still more preferably 17.0%.
The BaO component can be contained in the glass using, for example, BaO or a carbonate, nitrate, hydroxide, or the like as a raw material.

The ZnO component has the effect of lowering the glass transition temperature (Tg) and improving chemical durability. However, if the amount is too large, the devitrification resistance tends to deteriorate. Therefore, the upper limit of the amount of this component should preferably be 40.0%, more preferably 30.0%, still more preferably 20.0%, and most preferably 3.0%.
The ZnO component can be contained in the glass using, for example, ZnO as a raw material.

The Al ₂ O ₃ component is an optional component effective for improving chemical durability. However, if the amount is too large, the devitrification resistance tends to deteriorate. Accordingly, the upper limit is preferably 20.0%, more preferably 15.0%, and still more preferably 10.0%.
The Al ₂ O ₃ component can be contained in the glass using, for example, Al ₂ O ₃ or Al (OH) ₃ as a raw material.

The ZrO ₂ component has the effect of increasing the refractive index, reducing the partial dispersion ratio, and improving the chemical durability. However, if the amount is too large, the devitrification resistance tends to deteriorate. Accordingly, the upper limit is preferably 20.0%, more preferably 15.0%, and still more preferably 10.0%.
The ZrO ₂ component can be contained in the glass using, for example, ZrO ₂ as a raw material.

The La ₂ O ₃ component is an effective component for increasing the refractive index of the glass and reducing the dispersion. However, if the amount is too large, the devitrification resistance tends to deteriorate. Accordingly, the upper limit is preferably 20.0%, more preferably 15.0%, and still more preferably 10.0%.
The La ₂ O ₃ component can be contained in the glass using, for example, La ₂ O ₃ , lanthanum nitrate or a hydrate thereof as a raw material.

The Gd ₂ O ₃ component is effective for increasing the refractive index of the glass and lowering the dispersion. However, if the amount is too large, the devitrification resistance tends to deteriorate. Therefore, it can contain preferably 20.0%, more preferably 15.0%, and even more preferably 10.0.
Gd ₂ O ₃ can be contained in the glass using, for example, Gd ₂ O ₃ as a raw material.

The Y ₂ O ₃ component is effective in increasing the refractive index of the glass and lowering the dispersion. However, if the amount is too large, the devitrification resistance tends to deteriorate. Accordingly, the upper limit is preferably 20.0%, more preferably 15.0%, and still more preferably 10.0%.
The Y ₂ O ₃ component can be contained in the glass using, for example, Y ₂ O ₃ as a raw material.

The Ta ₂ O ₅ component has an effect of increasing the refractive index and improving chemical durability and devitrification resistance. However, if the amount is too large, the devitrification resistance tends to deteriorate. Accordingly, the upper limit is preferably 20.0%, more preferably 15.0%, and still more preferably 10.0%.
The Ta ₂ O ₅ component can be contained in the glass using, for example, Ta ₂ O ₅ as a raw material.

The In ₂ O ₃ component is effective in increasing the refractive index of the glass and lowering the dispersion. Accordingly, the upper limit is preferably 20.0%, more preferably 15.0%, and still more preferably 10.0%.
The In ₂ O ₃ component can be contained in the glass using, for example, In ₂ O ₃ or In ₂ F ₃ as a raw material.

The Yb ₂ O ₃ component is effective in increasing the refractive index of the glass and lowering the dispersion. However, if the amount is too large, devitrification resistance and chemical durability are likely to deteriorate. Therefore, the upper limit is preferably 20.0%, preferably 15.0%, more preferably 10.0%.
The Yb ₂ O ₃ component can be contained in the glass using, for example, Yb ₂ O ₃ as a raw material.

The Ga ₂ O ₃ component is a component having an effect of increasing the refractive index, but the raw material is very expensive. Accordingly, the upper limit is preferably 10.0%, more preferably 8.0%, and still more preferably 5.0%.
The Ga ₂ O ₃ component can be contained in the glass using, for example, Ga ₂ O ₃ as a raw material.

The CeO ₂ component is a component having an effect of improving devitrification resistance. However, if the amount is too large, the light transmittance in the short wavelength region is likely to deteriorate. Accordingly, the upper limit of the amount of this component is preferably 1.0%, more preferably 0.8%, and still more preferably 0.5%.
The CeO ₂ component can be contained in the glass using, for example, CeO ₂ as a raw material.

The Sb ₂ O ₃ component can be optionally added for defoaming when the glass is melted, but if the amount is too large, the transmittance in the short wavelength region of the visible light region tends to deteriorate. Accordingly, the upper limit of the amount of this component is preferably 1.0%, more preferably 0.8%, and still more preferably 0.5%.
Note that the content (%) of the Sb ₂ O ₃ component means an externally added amount (mol%). Here, the “outside split” represents the mol% of Sb ₂ O ₃ alone in terms of oxide, when the molar amount of the whole glass composition component excluding the Sb ₂ O ₃ component is 100.

In the optical glass of the present invention, the substance amount ratio of the substance amount sum (Li ₂ O + K ₂ O) to Na ₂ O is preferably 2.00 or less. By setting the substance amount ratio to 2.00 or less, the partial dispersion ratio (θg, F) can be reduced. Therefore, the substance ratio (Li ₂ O + K ₂ O) / Na ₂ O with respect to the total glass substance quantity of the oxide conversion composition is preferably 2.00%, more preferably 1.70%, and even more preferably 1.435%. Can be contained as an upper limit.

  In addition, the raw material used in order to contain each component which exists in the said glass was described for the purpose of illustration, and is not limited to the said enumerated oxide etc. That is, it can be selected from known raw materials in accordance with various changes in the glass production conditions.

Lu ₂ O _3, but the components of SnO _2, BeO is possible to contain, Lu ₂ O ₃ in an actual manufacturing becomes high raw material cost because it is expensive raw materials impractical, SnO ₂ is When a glass raw material is melted in a platinum crucible or in a melting tank where the molten glass is made of platinum, the portion where tin and platinum are alloyed to become an alloy has poor heat resistance. There is concern about the danger of accidents in which holes are opened and molten glass flows out, and there is a problem that BeO is a component that has a harmful effect on the environment and a very large environmental load. Accordingly, it is preferably contained in an amount of less than 0.1%, more preferably 0.05%, and even more preferably not contained.

  Next, components that should not be contained in the optical glass of the present invention will be described.

  Since lead compounds are a component that has a large environmental impact, not only for glass production, but also for cold processing of glass such as polishing and disposal of glass. It should not be included in the optical glass of the invention.

As ₂ O ₃ , cadmium, thorium and thallium all have harmful effects on the environment and are extremely heavy components of the environment, and therefore should not be contained in the optical glass of the present invention.

  Furthermore, it is preferable that the optical glass of the present invention does not contain coloring components such as V, Cr, Mn, Fe, Co, Ni, Cu, Mo, Eu, Nd, Sm, Tb, Dy, and Er. However, the term “not contained” means that it is not contained artificially unless it is mixed as an impurity.

  In addition, the notation on the basis of oxides of the content of each component used in this specification is that all oxides, composite salts, metal fluorides, etc. used as raw materials for the glass constituents of the present invention are melted. When it assumes that it decomposes | disassembles and changes to an oxide, it represents the mol% of the said production | generation oxide of each component with respect to the whole composition.

  Next, the physical properties of the optical glass of the present invention will be described.

In the optical glass of the present invention, the partial dispersion ratio (θg, F) needs to be close to the normal line. More specifically, in the optical glass of the present invention, the partial dispersion ratio (θg, F) is in the range of ν _d ≦ 25 between the Abbe number (ν _d ) and the formula (1): [(−0. 0016 × ν _d +0.63460) ≦ (θg, F) ≦ (−0.00563 × ν _d +0.75873)]. Accordingly, the position of the plot of the partial dispersion ratio (θg, F) and the Abbe number (ν _d ) is brought close to the normal line (Normal Line) in FIG. 1 while having high dispersion. Therefore, it can be inferred that chromatic aberration due to an optical element using this optical glass is reduced.
In such a range of ν _d ≦ 25, it is preferable to satisfy the relationship (−0.0016 × ν _d +0.63660) ≦ (θg, F), and (−0.0016 × ν _d +0.63860) ≦ ( It is more preferable to satisfy the relationship of θg, F).
Further, in such a range of ν _d ≦ 25, it is preferable to satisfy the relationship (θg, F) ≦ (−0.00563 × ν _d +0.755673), and (θg, F) ≦ (−0.00563 ×). It is more preferable to satisfy the relationship of ν _d +0.75473), and it is further preferable to satisfy the relationship of (θg, F) ≦ (−0.00563 × ν _d +0.75273).
Further, in the optical glass of the present invention, the partial dispersion ratio (θg, F) is in the range of ν _d > 25 between the Abbe number (ν _d ) and the formula (2): [(−0.0025 × ν _d +0.65710) ≦ (θg, F) ≦ (−0.0034 × ν _d +0.70300)].
In such a range of ν _d > 25, it is preferable to satisfy the relationship (−0.0025 × ν _d +0.65910) ≦ (θg, F), and (−0.0025 × ν _d +0.66110) ≦ ( It is more preferable to satisfy the relationship of θg, F).
In such a range of ν _d > 25, it is preferable to satisfy the relationship of (θg, F) ≦ (−0.00340 × ν _d +0.70100), and (θg, F) ≦ (−0.00340 × (ν _d +0.69900) is more preferable, and (θg, F) ≦ (−0.00340 × ν _d +0.69700) is more preferable. In particular, in a region where the Abbe number (ν _d ) is small, the partial dispersion ratio (θg, F) of general glass is higher than that of the normal line, and the partial dispersion ratio (θg, F) of general glass is high. And the Abbe number (ν _d ) are represented by curves. However, since it is difficult to approximate this curve, the present invention uses a straight line having a different slope from ν _d = 25 as a partial dispersion ratio (θg, F) lower than that of general glass. Expressed.
The optical glass of the present invention satisfies such a relationship. That is, it is an optical glass having a high refractive index and high dispersibility and a small partial dispersion ratio.

  In the present invention, the partial dispersion ratio (θg, F) is the refractive index (nC) in the C line (wavelength 656.27 nm) and the F line for the optical glass obtained at a slow cooling rate of -25 ° C / hour. The refractive index (nF) at (wavelength 486.13 nm) and the refractive index (ng) at the g line (wavelength 435.835 nm) are measured, and the formula by (θg, F) = (ng−nF) / (nF−nC) It means the value calculated in.

The optical glass of the present invention further has good transmittance. Specifically, the wavelength (λ ₈₀ ) at which the transmittance is 80% is preferably 655 nm or less, more preferably 600 nm or less, and even more preferably 550 nm or less. The wavelength (λ ₇₀ ) at which the transmittance is 70% is preferably 500 nm or less, more preferably 480 nm or less, still more preferably 450 nm or less, and most preferably 420 nm or less. The wavelength (λ ₅ ) at which the transmittance is 5% is preferably 450 nm or less, more preferably 420 nm or less, and still more preferably 400 nm or less.
Incidentally, the transmittance is relative to the incident light intensity when irradiated perpendicularly to one of the optically polished surfaces of a glass sample subjected to parallel and flat optical polishing having a thickness of 10.0 ± 0.1 mm. It is represented by the ratio of the intensity of transmitted light transmitted through the glass sample and emitted from the other optical polishing surface (transmitted light intensity / incident light intensity). The wavelength at which the transmittance is 80% is λ ₈₀ , the wavelength at 70% is λ ₇₀ , and the wavelength at 5% is λ ₅ .

The optical glass of the present invention has a refractive index (n _d ) of 1.70 or more and 2.00 or less, an Abbe number (ν _d ) of 15 or more and 29.5 or less, and a spectral transmittance of 70. % (Λ ₇₀ ) is preferably 500 nm or less.
Here, the refractive index (n _d ) is preferably 1.70 or more, more preferably 1.74 or more, and even more preferably 1.78 or more. Further, the refractive index (n _d ) is preferably 2.00 or less, more preferably 1.98 or less, and further preferably 1.96 or less.
The Abbe number (ν _d ) is more preferably 15 or more, more preferably 17 or more, and further preferably 19 or more. Further, the Abbe number (ν _d ) is more preferably 29.5 or less, more preferably 28 or less, more preferably 27 or less, and even more preferably 26 or less.

  As described above, the optical glass of the present invention is an optical glass having a high refractive index and a high dispersibility, a small partial dispersion ratio, and a good transmittance.

In the optical glass of the present invention, when the glass transition point (Tg) becomes too high, as described above, when precision press molding is performed, deterioration of the mold tends to occur. Therefore, Tg of the optical glass of the present invention is preferably 700 ° C., more preferably 680 ° C., and further preferably 650 ° C.
The yield point (At) is preferably 750 ° C., more preferably 730 ° C., and still more preferably 700 ° C. or less.

  The optical glass of the present invention is useful for various optical elements and optical designs. For example, the optical glass of the present invention can be ground and polished to obtain an optical glass. Further, for example, an optical glass for precision press molding can be obtained from the optical glass of the present invention. Among them, it is particularly preferable to form a preform from the optical glass of the present invention, and to produce optical elements such as lenses, prisms, mirrors and the like by using means such as polishing and precision press molding for the preform. . As a result, when used in optical devices that transmit visible light to optical elements such as cameras and projectors, the optical system in these optical devices can be miniaturized while realizing high-definition and high-precision imaging characteristics. Can be planned. Here, the method for producing the preform material is not particularly limited. For example, a glass gob forming method described in JP-A-8-319124 and an optical glass manufacturing method and manufacturing apparatus described in JP-A-8-73229 are disclosed. Thus, a method of manufacturing a preform material directly from molten glass can also be used, and a method of manufacturing by performing cold processing such as grinding and polishing on a strip material formed from optical glass can also be used.

  Examples of the present invention will be described below, but the present invention is not limited to these examples.

The compositions of Examples 1 to 29 of the glass of the present invention and the compositions of Comparative Examples 1 to 3 are compared with the refractive index (n _d ), Abbe number (ν _d ), partial dispersion ratio (θg, F), λ of these glasses. ₈₀ , λ ₇₀ , λ ₅ , refractive index (nC) at C line (wavelength 656.27 nm), refractive index (nF) at F line (wavelength 486.13 nm), refractive index at g line (wavelength 435.835 nm) ( ng) and shown in Tables 1-4. Among these, Examples 1-3 and 6-10 are taken as reference examples of the present invention. In the table, the composition of each component is expressed in mol%. Further, the content (%) of the Sb ₂ O ₃ component means an externally added amount (mol%). Moreover, the relationship of the Abbe number ((nu) _d ) and the partial dispersion ratio ((theta) g, F) in the glass of Examples 1-29 and Comparative Examples 1-3 is shown in FIG.

  The optical glass of Examples of the present invention (Examples 1 to 29) shown in Tables 1 to 3 shows ordinary optical glass raw materials such as oxides, hydroxides, carbonates and nitrates in Tables 1 to 4. Weighing, mixing, and pouring into a platinum crucible at the composition ratio of each example, and homogenizing by melting, clarifying, and stirring at 900 to 1400 ° C. for 3 to 5 hours according to the meltability depending on the composition Then, it was obtained by casting into a mold or the like and gradually cooling.

The refractive index (n _d ) and the Abbe number (ν _d ) were measured for the optical glass obtained at a slow cooling rate of −25 ° C./hour.

  The partial dispersion ratio (θg, F) is the refractive index (nC) in the C line (wavelength 656.27 nm) and the F line (wavelength 486.13 nm) of the optical glass obtained by setting the slow cooling rate to −25 ° C./hour. ) And the refractive index (ng) at the g-line (wavelength 435.835 nm) were measured and calculated by the formula of θg, F = (ng−nF) / (nF−nC).

Further, λ ₈₀ , λ ₇₀ , and λ ₅ were measured using “U-4100” manufactured by Hitachi, Ltd.

As can be seen from Tables 1 to 3, the Abbe number (ν _d ) and the partial dispersion ratio (θg, F) in the optical glasses of Examples of the present invention (Examples 1 to 29) are expressed by the following formulas (1) and ( It satisfies 2). Also, the refractive index (n _d ) is 1.77 or higher and is high. Further, λ ₈₀ is 524.5 nm or less, λ ₇₀ is 447.5 nm or less, and λ ₅ is 390 nm or less. That is, the transmittance is also good. Therefore, it can be said that the optical glasses of Examples 1 to 29 have high refractive index and high dispersibility, a small partial dispersion ratio, and good transmittance.

Further, as shown in FIG. 2, in the optical glasses of Examples 1 to 29, the partial dispersion ratio (θg, F) is (−0.00250 ××) when ν _d > 25 in relation to the Abbe number (ν _d ). ν _d +0.65710) or more, more specifically (−0.00250 × ν _d +0.66110) or more, (−0.00340 × ν _d +0.70300) or less, and more specifically (−0. And (−0.00160 × ν _d +0.63460) or more at νd ≦ 25, more specifically, (−0.00160 × ν _d +0.63860) or more, −0.00563 × ν _d +0.75873) or less. In the optical glasses of Comparative Examples 1 to 3, the partial dispersion ratio (θg, F) exceeds (−0.00340 × νd + 0.70300) when ν _d > 25, and (−0) when νd ≦ 25. .00563 × νd + 0.75873). For this reason, it became clear that the optical glass of the Example of this invention has a partial dispersion ratio ((theta) g, F) near a normal line, and a small chromatic aberration compared with the glass of Comparative Examples 1-3).

  Furthermore, using the optical glass of the example of the present invention, after forming a preform for polishing, grinding and polishing were performed to form lenses and prisms. In addition, a precision press-molding preform was formed using the optical glass of the example of the present invention, and the precision press-molding preform was precision press-molded into a lens and a prism. In either case, it could be processed into various lens and prism shapes.

Claims (5)

It contains 10.0 to 60.0% of P ₂ O ₅ component and 5.0 to 45.0% of Nb ₂ O ₅ component in mol% with respect to the total amount of glass in oxide conversion composition,
The content of TiO ₂ component is 30.0% or less,
B ₂ O ₃ component content is less than 5.0%,
The content of the WO ₃ component is 3. 0% or less,
2. BaO component content is 3. 0% or less under,
Li ₂ O component content exceeds 0% and 30.0% or less
The content of GeO ₂ component is 8.5% or less,
Bi ₂ O ₃ content is 9% or less
TeO ₂ component content is 7.6% or less,
Having a refractive index (n _d ) of 1.70 or more and 1.87 or less,
Having an Abbe number (ν _d ) of 15 or more and 29.5 or less,
The substance amount ratio TiO ₂ / Nb ₂ O ₅ is 0.63 or less,
The substance amount ratio (Li ₂ O + K ₂ O) / Na ₂ O is 1.435 or less,
The wavelength (λ ₇₀ ) at which the spectral transmittance shows 70% is 500 nm or less,
(−0.0016 × ν _d +0.63460) ≦ (θg, F) ≦ (−0...) In a range where the partial dispersion ratio (θg, F) is Abbe number (ν _d ) and ν _d ≦ 25. 00563 × ν _d +0.75873), and in the range of ν _d > 25, (−0.0025 × ν _d +0.65710) ≦ (θg, F) ≦ −0.0034 × ν _d +0.70300 Optical glass that satisfies the relationship. SiO ₂ component 0 to 30.0% in mol% with respect to the total amount of glass in oxide equivalent composition
Na ₂ O component 0-50.0%
K ₂ O component 0 to 25.0%
Cs ₂ O component 0 to 20.0%
MgO component 0 to 15.0%
CaO component 0 to 20.0%
SrO component 0 to 20.0%
ZnO component 0-40.0%
Al ₂ O ₃ component 0 to 20.0%
ZrO ₂ component 0 to 20.0%
La ₂ O ₃ component 0 to 20.0%
Gd ₂ O ₃ component 0 to 20.0%
Y ₂ O ₃ component 0 to 20.0%
Ta ₂ O ₅ component 0 to 20.0%
In ₂ O ₃ component 0 to 20.0%
Yb ₂ O ₃ component 0 to 20.0%
CeO ₂ component 0-1.0%
Sb ₂ O ₃ component 0 to 1.0%
The optical glass according to claim 1, further comprising: An optical element that can be ground and polished optical glass according to claim 1 or 2. Optical element formed by precision press molding an optical glass according to claim 1 or 2. Claim 1 or preform for precision press molding comprised of the optical glass according to 2.

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