KR20130123824A - Wide-angle lens system for visible ray and near infrared rays - Google Patents

Abstract

The present invention relates to a wide-angle lens system for visible ray and near infrared rays which is applicable for a vehicle and a monitoring camera and which performing excellent optical performance in a visible ray band and an near infrared ray band. The wide-angle lens system for visible ray and near infrared rays includes a first glass lens of a convex meniscus type convex toward an object which has a negative refractive force successively from objects; a second plastic lens of a meniscus type which has a positive refractive force and includes at least one non-aspherical surface and which is recessed toward an object; a third plastic lens which has a positive refractive force and which includes at least one non-aspherical surface; a forth glass lens of both-side convex shape which has a positive refractive force; and a fifth plastic lens which has a negative refractive force and which includes at least one non-aspherical surface. The present invention is provided to reduce manufacturing costs by utilizing two glass lenses or less and to photograph a subject within a visible ray region and a near infrared ray region at high definition and obtain enough definition even though the temperature is changed within a range of (-20~80.

Description

Wide-angle lens system for visible ray and near infrared rays}

The present invention relates to a wide-angle lens system for visible light and near infrared light that can be applied to vehicles and surveillance cameras and exhibits excellent optical performance even in the visible light and near infrared bands.

Generally, a camera is mounted on a mobile communication terminal, a computer, a notebook computer, and a vehicle so that the user can view the surrounding image information or take a picture. Cameras are also required to have a small size, light weight and high image quality according to the trend of slimming of mobile communication terminals and miniaturization of computers and laptops. Camera is required. In addition, such a camera should have a large angle of view to obtain as wide a range of image information as possible.

1 is a diagram illustrating a conventional wide-angle lens system.

The wide-angle lens system includes a first lens L1, a second lens L2, a third lens L3, an aperture AS, a fourth lens L4, a fifth lens L5, and the like from an object side. The sixth lens L6 is disposed. An optical filter OF such as an infrared filter and a cover glass is disposed between the sixth lens 6 and the imaging surface IP.

The first lens L1 and the second lens L2 have a meniscus shape convex toward the object side, and the radiuses of curvature of the object-side surfaces 1 and 3 are smaller than those of the image-side surfaces 2 and 4. Big.

The third lens L3 and the fourth lens L4 are formed such that the object side surfaces 5 and 7 are convex toward the object side, and the image side surfaces 6 and 8 are convex toward the image side.

The fifth lens L5 is bonded to the fourth lens L4 to form one lens group. The fifth lens L5 is formed such that the object side surface 9 is concave toward the object side and the image side surface 10 is concave toward the image side. The sixth lens L6 is formed such that the object side surface 11 is convex toward the object side and the image side surface 12 is convex toward the image side.

This conventional wide-angle lens system is made by mixing six spherical glass lenses and aspherical glass lenses to realize a wide angle. In the extreme, at least 5 to 6 glass lenses should be used to guarantee the same resolution under severe temperature conditions inside and outside the vehicle.

Such a wide-angle lens system has an advantage of a small change in resolution due to the characteristics of the glass material, but in order to achieve high resolution, the number of glass lenses must be increased. In addition, in order to reduce the manufacturing cost, it should be composed only of spherical glass lenses, in which case there is a limit in increasing the resolution of the wide-angle lens system.

If the number of plastic lenses is increased to increase the resolution and reduce the number of lenses, the change in the resolution may occur due to the change of the refractive index due to the temperature change of the plastic material under the severe temperature conditions of the vehicle and the external surveillance environment, and thus the result may not be satisfactory. .

In addition, such a wide-angle lens system has a problem in that the optical performance in the infrared region is remarkably degraded, so that it is impossible to capture images at a satisfactory resolution in both the visible region and the near infrared region including the wavelength band of 400 to 950 nm without separate focusing. .

Accordingly, the present invention has been invented in view of the above circumstances, and it is possible to capture a subject at high resolution in both the visible and near-infrared region while reducing the production cost by limiting the use of the glass lens to less than two sheets, and having a wide temperature change. It is an object of the present invention to provide a wide-angle lens system for visible light and near infrared light that can guarantee resolution even at (-20 ° C. to 80 ° C.).

According to an aspect of the present invention for achieving the above object, a wide-angle lens system for visible light and near infrared light, the first glass lens of the meniscus type having negative refractive power in order from the object side and convex toward the object side; A second plastic lens of a meniscus type having positive refractive power and concave toward the object and having at least one surface aspherical; A third plastic lens having positive refractive power and at least one surface being aspherical; iris; A fourth glass lens having positive refractive power and double-sided convex; A fifth plastic lens having negative refractive power and at least one surface being aspherical; .

In addition, both surfaces of the first glass lens and the fourth glass lens are spherical surfaces.

In addition, both surfaces of the fifth plastic lens are concave.

In addition, the fourth glass lens is made of Abbe's number of 50 or more.

In addition, the fifth plastic lens has a refractive index of 1.6 or more.

In addition, among the lenses, the fourth glass lens has the highest refractive power.

In addition, among the lenses, the refractive power of the second plastic lens is the lowest.

Further, the wide angle lens system for visible light and near infrared light satisfies the following conditions.

0.01 <| K1 / Kt | <0.5

Here, K1 is the refractive power of the first glass lens, Kt is the refractive power of the entire lens system.

Further, the wide angle lens system for visible light and near infrared light satisfies the following conditions.

0.01 <| K2 / Kt | <0.5

Here, K2 is the refractive power of the second plastic lens, Kt is the refractive power of the entire lens system.

Further, the wide angle lens system for visible light and near infrared light satisfies the following conditions.

0.01 <| K3 / Kt | <0.5

Here, K3 is the refractive power of the third plastic lens, Kt is the refractive power of the entire lens system.

Further, the wide angle lens system for visible light and near infrared light satisfies the following conditions.

0.4 <| K4 / Kt | <1

Here, K4 is the refractive power of the fourth glass lens, Kt is the refractive power of the entire lens system.

Further, the wide angle lens system for visible light and near infrared light satisfies the following conditions.

0.4 <| K5 / Kt | <1

Here, K5 is the refractive power of the fifth plastic lens, Kt is the refractive power of the entire lens system.

According to another aspect of the present invention for achieving the above object, a wide-angle lens system for visible light and near infrared light, the first polymer lens having a negative refractive power in order from the object side, convex toward the object side and at least one surface is aspherical; A second plastic lens of a meniscus type having positive refractive power and concave toward the object and having at least one surface aspherical; A third plastic lens having positive refractive power and at least one surface being aspherical; iris; A fourth glass lens having positive refractive power and double-sided convex; A fifth plastic lens having negative refractive power and at least one surface being aspherical; .

In addition, the first polymer lens is manufactured by thermal curing or UV irradiation curing.

In addition, the first polymer lens is made of Abbe's number of 50 or more.

According to the present invention, it is possible to reduce the production cost by limiting the use of the glass lens to less than two sheets, and to capture a high-resolution image of the subject in both visible and near-infrared region, and at the same time, a wide temperature change (-20 ° C to 80 ° C). ) Can provide a wide-angle lens system for visible light and near infrared light that can guarantee resolution.

1 is a diagram illustrating a conventional wide-angle lens system.
2 is a diagram showing the configuration of a wide-angle lens system for visible light and near infrared light according to an embodiment of the present invention.
3A is a diagram showing the configuration of a wide-angle lens system for visible light and near infrared light according to the first embodiment of the present invention.
3B to 3D are graphs of resolutions of temperature of a wide-angle lens system for visible light and near infrared light according to a first exemplary embodiment of the present invention in the visible light region.
3E to 3G are graphs of resolutions according to temperatures of a wide-angle lens system for visible light and near infrared light according to a first exemplary embodiment of the present invention in the near infrared region.
4A is a diagram showing the configuration of a wide-angle lens system for visible light and near infrared light according to a second embodiment of the present invention.
4B to 4D are graphs of resolutions of temperature of a wide-angle lens system for visible light and near infrared light according to a second exemplary embodiment of the present invention in the visible light region.
4E to 4G are graphs of resolutions according to temperatures of a wide-angle lens system for visible light and near infrared light according to a second exemplary embodiment of the present invention in the near infrared region.
5A is a diagram showing the configuration of a wide-angle lens system for visible light and near infrared light according to a third embodiment of the present invention.
5B to 5D are graphs of resolutions of temperature of a wide-angle lens system for visible light and near infrared light according to a third exemplary embodiment of the present invention in the visible light region.
5E to 5G are graphs of resolutions according to temperatures of a wide-angle lens system for visible light and near infrared light according to a third exemplary embodiment of the present invention in the near infrared region.
6A is a diagram showing the configuration of a wide-angle lens system for visible light and near infrared light according to a fourth embodiment of the present invention.
6B to 6D are graphs of resolutions of temperature of a wide-angle lens system for visible light and near infrared light according to a fourth exemplary embodiment of the present invention in the visible light region.
6E to 6G are graphs of resolutions according to temperatures of a wide-angle lens system for visible light and near infrared light according to a fourth exemplary embodiment of the present invention in the near infrared region.
7 is a diagram illustrating the configuration of a wide-angle lens system for visible light and near infrared light according to another embodiment of the present invention.
8A is a diagram showing the configuration of a wide-angle lens system for visible light and near infrared light according to a fifth embodiment of the present invention.
8B to 8D are graphs of resolutions according to temperatures of a wide-angle lens system for visible light and near infrared light according to a fifth exemplary embodiment of the present invention in the visible light region.
8E to 8G are graphs of resolutions according to temperatures of a wide-angle lens system for visible light and near infrared light according to a fifth exemplary embodiment of the present invention in the near infrared region.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. In the drawings, like reference numerals refer to like elements throughout. The same reference numerals in the drawings denote like elements throughout the drawings.

2 is a diagram showing the configuration of a wide-angle lens system for visible light and near infrared light according to an embodiment of the present invention.

The wide-angle lens system (hereinafter, referred to as a wide-angle lens system) for visible light and near infrared light may include a first glass lens L1, a second plastic lens L2, a third plastic lens L3, and an aperture 160 in order from an object side. And a fourth glass lens L4 and a fifth plastic lens L5. The first glass lens L1, the second plastic lens L2, and the third plastic lens L3 form a first lens group, and the fourth glass lens L4 and the fifth plastic lens L5 are second A lens group is formed.

The first glass lens L1 is a lens located closest to the object side. The first glass lens L1 has a negative refractive power and is formed in a meniscus type in which it is convex toward the object side. The first glass lens L1 is closest to the external environment, and is formed of a glass material in order to withstand external scratches and humidity and to converge wide angle light. Both surfaces of the first glass lens L1 may be spherical surfaces, and the radius of curvature of the object-side surface 111 is greater than the radius of curvature of the image-side surface 112.

The second plastic lens L2 is located after the first glass lens L1. The second plastic lens L2 is a meniscus-type lens that is concave toward the object and at least one surface is aspheric and is formed of a plastic material. The second plastic lens (L2) is the opposite of the first glass lens (L1) to reduce the angle of the light incident from the first glass lens (L1) to be easily formed on the lens provided after the aperture 160 Has refractive power. In addition, the second plastic lens L2 verticalizes the light to the aperture, thereby enabling high resolution. Reference numeral 121 denotes an object side surface of the second plastic lens L2, and 122 denotes an image side surface of the second plastic lens L2.

It is preferable that the second plastic lens L2 has the lowest refractive power among the lenses. Refractive power refers to the power of the lens as 1 / focal length f. High refractive power means good power to break light. When a large amount of power is applied to a plastic lens, the focal distance and the like may be changed according to the temperature change, resulting in a relatively large resolution change depending on the temperature. Therefore, the second refractive lens is placed relatively close to the external environment and the lowest refractive power is given to the second plastic lens L2 made of plastic material, thereby minimizing the resolution change according to temperature.

The third plastic lens L3 is located next to the second plastic lens L2. The third plastic lens L3 has a positive refractive power and at least one surface is aspherical and formed of a plastic material. The third plastic lens L3 may be formed in a meniscus type concave toward the object side or may have a convex shape on both sides. The third plastic lens L3 reduces the angle of the light incident from the first glass lens L1 so that the third plastic lens L3 can be easily imaged on the lens provided after the aperture 160. In addition, the third plastic lens L3 verticalizes the light to the aperture 160 to realize high resolution. Reference numeral 131 denotes an object side surface of the third plastic lens L3, and 132 denotes an image side surface of the third plastic lens L3.

The aperture 160 is positioned after the third plastic lens L3. The aperture 160 adjusts the size of the hole to adjust the amount of light passing through the lens.

The fourth glass lens L4 is positioned after the diaphragm 160. The fourth glass lens L4 has positive refractive power and is formed of a glass material having a double-sided convex shape. The fourth glass lens L4 is made of a double-sided spherical lens, thereby lowering the manufacturing cost and facilitating assembly. The fourth glass lens L4 is preferably made of a glass lens having an Abbe's number of 50 or more to correct chromatic aberration for each wavelength. Abbe's number is a number which shows the property regarding the dispersion | distribution of the light of optical glass, and the larger the Abbe's number, the less the color dispersion occurs and a clear image can be obtained. Reference numeral 141 denotes an object side surface of the fourth glass lens L4, and 142 denotes an image side surface of the fourth glass lens L4.

It is preferable that the 4th glass lens L4 has the highest refractive index among each lens. The glass material has a rate of change with temperature which is one-tenth of that of plastic, and has excellent reliability according to the temperature change. When a large amount of power is applied to a plastic lens, the focal distance and the like may be changed according to the temperature change, resulting in a relatively large resolution change depending on the temperature. Therefore, among the five lenses, the highest refractive power is imparted to the fourth glass lens L4 formed of the glass material.

The fifth plastic lens L5 is located after the fourth glass lens L4. The fifth plastic lens L5 has a negative refractive power and is formed of a plastic material having at least one surface aspherical. Both surfaces of the fifth plastic lens L5 may be concave. The fifth plastic lens L5 is preferably formed of a plastic material having a high refractive index of 1.6 or more in order to realize high resolution. Reference numeral 151 denotes an object side surface of the fifth plastic lens L5, and 152 denotes an image side surface of the fifth plastic lens L5.

An optical filter 170 may be positioned between the fifth plastic lens L5 and the imaging surface 180. The optical filter 170 may be an infrared filter, a cover glass, or the like, and the optical filter 170 is considered to have no effect on optical performance.

The wide-angle lens system of the present invention uses only two glass lenses of the first glass lens L1 and the fourth glass lens L4, and both surfaces thereof are spherical so that manufacturing cost can be reduced. Since the first glass lens L1 is positioned at the outermost side in direct contact with the external environment, it is possible to efficiently cope with scratches and humidity using relatively durable glass. In addition, the fourth glass lens L4 may be made of a glass lens having an Abbe number of 50 or more, and may have the highest refractive power, thereby minimizing the resolution change due to the temperature change.

The second plastic lens L2, the third plastic lens L3, and the fifth plastic lens L5 are formed of a plastic material having at least one surface aspherical. The second plastic lens L2 located relatively close to the external environment has the lowest refractive power, thereby minimizing the change in resolution with temperature. The fifth plastic lens L5, which is farthest from the external environment and closest to the imaging surface 180, has a high refractive index of 1.6 or more, thereby increasing the resolution of the lens system.

Thus, the wide-angle lens system of the present invention is composed of a total of five lenses, limiting the use of the glass lens to less than two sheets while reducing the manufacturing cost, while realizing a wide-angle high resolution and a wide temperature change (-20 ℃) ~ 80 ℃) has the advantage that can guarantee the resolution. In addition, the wide-angle lens system of the present invention has the advantage that the image can be captured at an excellent resolution without focusing in the near infrared region (700 ~ 950nm) by implementing a wide-angle high resolution with a total of five lenses.

Hereinafter, first to fourth embodiments of the wide-angle lens system of the present invention will be described.

1st Example

3A is a diagram showing the configuration of a wide-angle lens system according to the first embodiment of the present invention. 3B to 3D are graphs of resolutions according to temperatures of the wide-angle lens system according to the first embodiment of the present invention in the visible light region. 3E to 3G are graphs of resolution according to temperature of the wide-angle lens system according to the first embodiment of the present invention in the near infrared region.

The following shows design data of the wide-angle lens system according to the first embodiment of the present invention.

lens if Radius of curvature thickness Refractive index Abe number Focal length Refractive ability The first lens Front page 13.04303 One 1.62041 60.32 -6.95013 0.318742 The second page 3.154995 2.368528 The second lens Front page -3.952684 3.234667 1.5324 56.04 21.09085 0.105036 The second page -3.822794 4.062404 Third lens Front page -12.1969 1.056789 1.5324 56.04 16.03664 0.13814 The second page -5.1765 0.05 Fourth lens Front page 3.1 2.4 1.62041 60.32 2.933051 0.755289 The second page -3.1 0.05 Fifth lens Front page -3.3051 0.672375 1.6328 23.35 -3.21392 0.689283 The second page 5.70408 1.431832

Here, the F number is 2.64, the total focal length is 2.2153mm, and the angle of view is 90 °.

The focal length is the longest of the second plastic lens L2 and the shortest of the fourth glass lens L4. Therefore, the refractive power of the second plastic lens L2 is the lowest, and the refractive power of the fourth glass lens L4 is the highest. Refractive power is the inverse of focal length. If the refractive power of the other lens is higher than the refractive power of the fourth glass lens L4, it becomes undesirable to be a temperature sensitive lens system.

| Kn / Kt | is an absolute value obtained by dividing the refractive power of each lens by the refractive power of all lenses, and represents the ratio of the refractive power of each lens to the refractive power of all lenses.

The refractive ability of the first glass lens L1 satisfies the following Conditional Expression 1.

0.01 <| K1 / Kt | <0.5 [Condition 1]

Here, K1 is the refractive power of the first glass lens L1, and Kt is the refractive power of the entire lens system.

The refractive power of the second plastic lens L2 satisfies the following conditional expression (2).

0.01 <K2 / Kt | <0.5 [Condition 2]

Here, K2 is the refractive power of the second plastic lens L2, and Kt is the refractive power of the entire lens system.

The refractive power of the third plastic lens L3 satisfies the following Conditional Expression 3.

0.01 <| K3 / Kt | <0.5 [Condition 3]

Here, K3 is the refractive power of the third plastic lens L3, Kt is the refractive power of the entire lens system.

The refractive ability of the fourth glass lens L4 satisfies the following Conditional Expression 4.

0.4 <| K4 / Kt | <1 [Condition 4]

Here, K4 is the refractive power of the fourth glass lens L4, and Kt is the refractive power of the entire lens system.

The refractive power of the fifth plastic lens L5 satisfies the following conditional expression (5).

0.4 <| K5 / Kt | <1 [Condition 5]

Here, K5 is the refractive power of the fifth plastic lens L5, and Kt is the refractive power of the entire lens system.

From the above Conditional Expressions 1 to 5, it can be seen that the refractive power of the first glass lens L1, the second plastic lens L2, and the third plastic lens L3 occupies a low ratio in the refractive power of the entire lens system. In addition, it can be seen that the refractive power of the fourth glass lens L4 and the fifth plastic lens L5 occupies a high ratio in the refractive power of the entire lens system. This is to reduce the change in resolution due to temperature change by providing low refractive power to the first glass lens L1, the second plastic lens L2, and the third plastic lens L3 which are relatively close to the external environment.

Matters relating to the aspherical surface used in this embodiment are obtained from the following equation.

[Equation 1]

Where Z is the distance from the vertex of the lens to the optical axis direction,

        Y: distance in the direction perpendicular to the optical axis,

        c is the inverse of the radius of curvature r at the vertices of the lens,

        K: Conic constant,

        A, B, C, D, E, F: Aspheric coefficient

In this embodiment, both surfaces of the second plastic lens L2, the third plastic lens L3, and the fifth plastic lens L5 are formed as aspheric surfaces. Conic constants and aspheric coefficients of the second plastic lens L2, the third plastic lens L3, and the fifth plastic lens L5 are as follows.

division The second lens Third lens Fifth lens Front page The second page Front page The second page Front page The second page K 0 -7.92461 12.41775 0 40.673808 20.381633 A4 0.001064 0.004194 -0.0004 -0.00095 0.010507 0.014397 A6 6.00E-05 -0.00015 0.003124 0.000451 0.006974 -0.00016 A8 1.73E-05 5.61E-05 -0.00236 -0.00033 -0.00226 0.004197 A10 3.84E-06 -2.41E-06 0.000554 1.54E-04 0.003513 -9.87E-04

3B, 3C, and 3D show graphs of resolution of the lens system at respective temperatures (20 ° C., 80 ° C., −20 ° C.) in the visible light region.

In the graph, the horizontal axis represents a spatial frequency, and the higher the value of the spatial frequency, the higher the resolution. For example, the highest value of 160 on the horizontal axis means that there are 160 pixel pairs (1 cycle) of black and white within 1 mm.

The vertical axis represents a Modulation Transfer Function (MTF), which indicates the degree to which pixel pairs can be resolved. The modulation transfer function is a function that indicates how well the lens system passes the spatial frequency to the image plane. If an image (several kinds of spatial frequencies) passes through the lens system and is reproduced at the same brightness on the image surface, the value of the modulation transfer function becomes "1", and becomes "0" when the image disappears completely on the image surface.

In addition, the color of a line, a straight line, a dotted line, etc. represent the resolution for each position. For example, in the graph, the solid red line is the resolution of light entering the center of the lens, green is the light coming in at 15 ° (half angle), blue is the light coming in at 30 ° (half angle), and purple is 45 ° (half angle). Indicates incoming light. The color of these lines represents the light entering the lens at four representative points (0 °, 15 °, 30 °, 45 °).

Looking at Figures 3b to 3d, it can be seen that the resolution of the wide-angle lens system at 20 ° C is similarly maintained at 80 ° C, -20 ° C. Therefore, the wide-angle lens system of the present embodiment can reduce the manufacturing cost by limiting the use of the glass lens to two sheets while reducing the total number of lenses. In addition, high resolution of a wide angle can be realized, and resolution can be guaranteed even under a wide range of temperature changes (-20 ° C to 80 ° C).

3E, 3F and 3G show graphs of resolution of the lens system at respective temperatures (20 ° C., 80 ° C., −20 ° C.) in the near infrared region.

3E to 3G, it can be seen that the resolution of the wide-angle lens system at 20 ° C in the near infrared region is sufficiently maintained at 80 ° C and -20 ° C. Therefore, the wide-angle lens system of the present embodiment can guarantee the resolution even in a wide range of temperature changes (-20 ° C. to 80 ° C.) while maintaining excellent resolution without additional focus adjustment even in the near infrared region.

Second Example

4A is a diagram showing the configuration of a wide-angle lens system according to the second embodiment of the present invention. 4B to 4D are graphs of resolutions according to temperatures of the wide-angle lens system according to the second embodiment of the present invention in the visible light region. 4E to 4G are graphs of resolution according to temperature of the wide-angle lens system according to the second exemplary embodiment of the present invention in the near infrared region.

The following shows design data of the wide-angle lens system according to the second embodiment of the present invention.

lens if Radius of curvature thickness Refractive index Abe number Focal length Refractive ability The first lens Front page 6 0.9 1.512391 58.0483 -10.2181 0.231354 The second page 2.653831 2.99164 The second lens Front page -3.858436 2.993886 1.5324 56.04 21.65461 0.109168 The second page -3.670257 4.01278 Third lens Front page -9.5157 1.121024 1.5324 56.04 18.35125 0.12882 The second page -5.0179 0.300432 Fourth lens Front page 3.1 2.4 1.62041 60.32 2.933051 0.805987 The second page -3.1 0.113207 Fifth lens Front page -2.623825 1.96555 1.6328 23.35 -3.81755 0.619245 The second page 39.30567 0.626603

Here, the F number is 2.25, the total focal length is 2.364 mm, and the angle of view is 80 °.

The focal length is the longest of the second plastic lens L2 and the shortest of the fourth glass lens L4. Therefore, the refractive power of the second plastic lens L2 is the lowest, and the refractive power of the fourth glass lens L4 is the highest. In addition, the refractive power of each lens satisfies the conditional expressions 1 to 5.

In this embodiment, both surfaces of the second plastic lens L2, the third plastic lens L3, and the fifth plastic lens L5 are formed as aspheric surfaces. Conic constants and aspheric coefficients of the second plastic lens L2, the third plastic lens L3, and the fifth plastic lens L5 are as follows.

division The second lens Third lens Fifth lens Front page The second page Front page The second page Front page The second page K 0 0 -5.92869 0 12.7103 1567.532 A4 -0.00363 0.000454 0.000758 0.007037 0.03638 0.02873 A6 -3.70E-04 -2.67E-06 0.008499 0.00254 0.003269 -0.00863 A8 3.97E-05 6.04E-05 -0.00342 0.000308 0.000506 0.007942 A10 9.25E-06 -2.90E-06 0.00086 3.04E-04 0.003957 -7.31E-04

4B, 4C and 4D show graphs of resolution of the lens system at respective temperatures (20 ° C., 80 ° C., −20 ° C.) in the visible region.

In the graph, the color of the line, the straight line, the dotted line, etc., represent the resolution for each position. For example, in the graph, the solid red line is the resolution of the light coming into the center of the lens, green is the light coming in at 15 ° (half angle), blue is the light coming in at 30 ° (half angle), and purple is 40 ° (half angle). Indicates incoming light.

Looking at Figures 4b to 4d, it can be seen that the resolution of the wide-angle lens system at 20 ° C is similarly maintained at 80 ° C and -20 ° C. Therefore, the wide-angle lens system of the present embodiment can reduce the manufacturing cost by limiting the use of the glass lens to two sheets while reducing the total number of lenses. In addition, high resolution of a wide angle can be realized, and resolution can be guaranteed even under a wide range of temperature changes (-20 ° C to 80 ° C).

4E, 4F and 4G show graphs of resolution of the lens system at respective temperatures (20 ° C., 80 ° C., −20 ° C.) in the near infrared region.

4E to 4G, it can be seen that the resolution of the wide-angle lens system at 20 ° C in the near infrared region is sufficiently maintained at 80 ° C and -20 ° C. Therefore, the wide-angle lens system of the present embodiment can guarantee the resolution even in a wide range of temperature changes (-20 ° C. to 80 ° C.) while maintaining excellent resolution without additional focus adjustment even in the near infrared region.

Third Example

5A is a diagram showing the configuration of a wide-angle lens system according to the third embodiment of the present invention. 5B to 5D are graphs of resolutions according to temperatures of the wide-angle lens system according to the third embodiment of the present invention in the visible light region. 5E to 5G are graphs of resolution according to temperature of the wide-angle lens system according to the third embodiment of the present invention in the near infrared region.

The following shows design data of the wide-angle lens system according to the third embodiment of the present invention.

lens if Radius of curvature thickness Refractive index Abe number Focal length Refractive ability The first lens Front page 5.618973 0.9 1.743985 44.8172 -10.1375 0.241589 The second page 3 2.485158 The second lens Front page -5.164315 3.834806 1.5324 56.04 18.63897 0.131397 The second page -4.272927 2.8 Third lens Front page -9.4848 1.646958 1.5324 56.04 15.20095 0.161115 The second page -4.6303 0.1 Fourth lens Front page 3.1 2.4 1.62041 60.32 2.933051 0.835001 The second page -3.1 0.115613 Fifth lens Front page -2.361265 1.530818 1.6328 23.35 -3.33883 0.73352 The second page 25.12518 0.730714

Here, the F number is 2.29, the total focal length is 2.449mm, and the angle of view is 86 °.

The focal length is the longest of the second plastic lens L2 and the shortest of the fourth glass lens L4. Therefore, the refractive power of the second plastic lens L2 is the lowest, and the refractive power of the fourth glass lens L4 is the highest. In addition, the refractive power of each lens satisfies the conditional expressions 1 to 5.

In this embodiment, both surfaces of the second plastic lens L2, the third plastic lens L3, and the fifth plastic lens L5 are formed as aspheric surfaces. Conic constants and aspheric coefficients of the second plastic lens L2, the third plastic lens L3, and the fifth plastic lens L5 are as follows.

division The second lens Third lens Fifth lens Front page The second page Front page The second page Front page The second page K 0 0 2.582887 0 1.379885 40.8581 A4 -0.00645 -0.001 0.000227 0.007154 0.052289 0.036612 A6 -3.26E-04 2.55E-04 0.010454 0.001817 -0.00664 -0.01045 A8 3.67E-05 5.50E-05 -0.00564 0.001697 0.008354 0.012277 A10 1.21E-05 -4.90E-06 0.002152 -5.56E-04 -0.00126 -2.37E-03

5B, 5C, and 5D show graphs of resolution of the lens system at 20 ° C., 80 ° C., and −20 ° C., respectively.

In the graph, the color of the line, the straight line, the dotted line, etc., represent the resolution for each position. For example, in the graph, the solid red line is the resolution of light entering the center of the lens, green is the light coming in at 15 ° (half angle), blue is the light coming in at 30 ° (half angle), and purple is 43 ° (half angle). Indicates incoming light.

5B to 5D, it can be seen that the resolution of the wide-angle lens system at 20 ° C is similarly maintained at 80 ° C and -20 ° C. Therefore, the wide-angle lens system of the present embodiment can reduce the manufacturing cost by limiting the use of the glass lens to two sheets while reducing the total number of lenses. In addition, high resolution of a wide angle can be realized, and resolution can be guaranteed even under a wide range of temperature changes (-20 ° C to 80 ° C).

5E, 5F and 5G show graphs of resolution of the lens system at respective temperatures (20 ° C., 80 ° C., −20 ° C.) in the near infrared region.

5E to 5G, it can be seen that the resolution of the wide-angle lens system at 20 ° C. in the near infrared region is sufficiently maintained at 80 ° C. and −20 ° C. Therefore, the wide-angle lens system of the present embodiment can guarantee the resolution even in a wide range of temperature changes (-20 ° C. to 80 ° C.) while maintaining excellent resolution without additional focus adjustment even in the near infrared region.

Fourth Example

6A is a diagram showing the configuration of a wide-angle lens system according to the fourth embodiment of the present invention. 6B to 6D are graphs of resolutions according to temperatures of the wide-angle lens system according to the fourth embodiment of the present invention in the visible light region. 6E to 6G are graphs of resolution according to temperature of the wide-angle lens system according to the fourth embodiment of the present invention in the near infrared region.

The following shows design data of the wide-angle lens system according to the fourth embodiment of the present invention.

lens if Radius of curvature thickness Refractive index Abe number Focal length Refractive ability The first lens Front page 5.990299 0.9 1.62041 60.32 -10.9483 0.223815 The second page 3 2.506201 The second lens Front page -6.277501 3.5 1.5324 56.04 19.94593 0.122852 The second page -4.81801 3.048517 Third lens Front page -9.2888 1.885735 1.5324 56.04 15.36307 0.159499 The second page -4.6562 0.05 Fourth lens Front page 3.1 2.4 1.62041 60.32 2.933051 0.835444 The second page -3.1 0.15 Fifth lens Front page -2.282242 1.944743 1.6328 23.35 -3.55076 0.690106 The second page 193.1217 0.569727

Here, the F number is 2.25, the total focal length is 2.45 mm, and the angle of view is 90 °.

The focal length is the longest of the second plastic lens L2 and the shortest of the fourth glass lens L4. Therefore, the refractive power of the second plastic lens L2 is the lowest, and the refractive power of the fourth glass lens L4 is the highest. In addition, the refractive power of each lens satisfies the conditional expressions 1 to 5.

In this embodiment, both surfaces of the second plastic lens L2, the third plastic lens L3, and the fifth plastic lens L5 are formed as aspheric surfaces. Conic constants and aspheric coefficients of the second plastic lens L2, the third plastic lens L3, and the fifth plastic lens L5 are as follows.

division The second lens Third lens Fifth lens Front page The second page Front page The second page Front page The second page K 0 0 17.39571 0 1.197332 173.888 A4 -0.00588 -0.00211 -0.00119 0.005356 0.042895 0.028873 A6 -3.68E-04 1.83E-04 0.009598 -0.0012 -0.00598 -0.01144 A8 -6.17E-06 5.47E-05 -0.00559 0.003409 0.008752 0.009612 A10 1.10E-05 -5.58E-06 0.002261 -1.12E-03 -0.00134 -9.55E-04

6B, 6C and 6D show resolution graphs of the lens system at 20 ° C., 80 ° C., and −20 ° C., respectively.

In the graph, the color of the line, the straight line, the dotted line, etc., represent the resolution for each position. For example, in the graph, the solid red line is the resolution of light entering the center of the lens, green is the light coming in at 15 ° (half angle), blue is the light coming in at 30 ° (half angle), and purple is 45 ° (half angle). Indicates incoming light.

Looking at Figures 6b to 6d, it can be seen that the resolution of the wide-angle lens system at 20 ° C is similarly maintained at 80 ° C and -20 ° C. Therefore, the wide-angle lens system of the present embodiment can reduce the manufacturing cost by limiting the use of the glass lens to two sheets while reducing the total number of lenses. In addition, high resolution of a wide angle can be realized, and resolution can be guaranteed even under a wide range of temperature changes (-20 ° C to 80 ° C).

6E, 6F and 6G show graphs of resolution of the lens system at respective temperatures (20 ° C., 80 ° C., −20 ° C.) in the near infrared region.

6E to 6G, it can be seen that the resolution of the wide-angle lens system at 20 ° C in the near infrared region is sufficiently maintained at 80 ° C and -20 ° C. Therefore, the wide-angle lens system of the present embodiment can guarantee the resolution even in a wide range of temperature changes (-20 ° C. to 80 ° C.) while maintaining excellent resolution without additional focus adjustment even in the near infrared region.

7 is a diagram showing the configuration of a wide-angle lens system according to another embodiment of the present invention.

The wide-angle lens system includes a first polymer lens L1, a second plastic lens L2, a third plastic lens L3, an aperture 260, a fourth glass lens L4, and a fifth plastic in order from the object side. The lens L5 is included. The first polymer lens L1, the second plastic lens L2, and the third plastic lens L3 form a first lens group, and the fourth glass lens L4 and the fifth plastic lens L5 are second A lens group is formed.

Except for the first polymer lens L1 in this embodiment, the configuration of the second plastic lens L2, the third plastic lens L3, the fourth glass lens L4, and the fifth plastic lens L5 is illustrated in FIG. The second plastic lens L2, the third plastic lens L3, the fourth glass lens L4, and the fifth plastic lens L5 shown in FIG. 2 are the same.

The first polymer lens L1 is a lens located closest to the object side. The first polymer lens L1 has negative refractive power, is convex toward the object side, and at least one surface is formed as an aspherical surface. In order to correct chromatic aberration for each wavelength, the first polymer lens L1 is preferably made of Abbe's number of 50 or more.

The first polymer lens L1 is formed of a polymer material and manufactured by thermal curing or UV (ultraviolet) irradiation curing. Here, the polymer is a higher concept of plastic, and plastic is a kind of polymer. In general, injection molding of a lens is a method in which a molten material is put into a mold to be cooled and hardened. In this embodiment, the first polymer lens L1 is hardened by applying heat or irradiating UV. The advantage of the polymer lens is that the aspheric surface can be easily applied since the molding can be molded according to the mold while the deformation sensitivity to temperature change is close to that of the glass material after molding.

Typical glass lenses are too difficult and expensive to apply aspherical surfaces. Therefore, in the present embodiment, the first glass lens L1 shown in FIG. 2 is replaced with the first polymer lens L1 to form a polymer, thereby reducing manufacturing cost and easily forming an aspherical surface. It can have the advantages of the glass material with little deformation.

In addition, in this embodiment, the low refractive power is imparted to the first polymer lens L1, so that it is not necessary to require high processing accuracy, and thus, the first glass lens L1 can be easily replaced with the first polymer lens L1. It becomes possible. As such, the wide-angle lens system of the present embodiment may have the advantages of the wide-angle lens system shown in FIG. 2 at a low cost of manufacturing the entire lens system.

The second plastic lens L2 is located after the first glass lens L1. The second plastic lens L2 is a meniscus type lens having a positive refractive power and concave toward the object side and having at least one surface aspherical surface formed of a plastic material. Reference numeral 221 denotes an object side surface of the second plastic lens L2, and 222 denotes an image side surface of the second plastic lens L2.

It is preferable that the second plastic lens L2 has the lowest refractive power among the lenses. Refractive power refers to the power of the lens as 1 / focal length f. When a large amount of power is applied to a plastic lens, the focal distance and the like may be changed according to the temperature change, resulting in a relatively large resolution change depending on the temperature. Therefore, the second refractive lens is placed relatively close to the external environment and the lowest refractive power is given to the second plastic lens L2 made of plastic material, thereby minimizing the resolution change according to temperature.

The third plastic lens L3 is located next to the second plastic lens L2. The third plastic lens L3 has a positive refractive power and at least one surface is aspherical and formed of a plastic material. The third plastic lens L3 may be formed in a meniscus type concave toward the object side or may have a convex shape on both sides. Reference numeral 231 denotes an object side surface of the third plastic lens L3, and 232 denotes an image side surface of the third plastic lens L3.

An aperture 260 is positioned after the third plastic lens L3. The aperture 260 adjusts the size of the hole to adjust the amount of light passing through the lens.

The fourth glass lens L4 is positioned after the stop 260. The fourth glass lens L4 has positive refractive power and is formed of a glass material having a double-sided convex shape. The fourth glass lens L4 is made of a double-sided spherical lens, thereby lowering the manufacturing cost and facilitating assembly. The fourth glass lens L4 is preferably made of a glass lens having an Abbe number of 50 or more to correct chromatic aberration for each wavelength. Reference numeral 241 denotes an object side surface of the fourth glass lens L4, and 242 denotes an image side surface of the fourth glass lens L4.

It is preferable that the 4th glass lens L4 has the highest refractive index among each lens. When a large amount of power is applied to a plastic lens, the focal distance and the like may be changed according to the temperature change, resulting in a relatively large resolution change depending on the temperature. Therefore, among the five lenses, the highest refractive power is imparted to the fourth glass lens L4 formed of the glass material.

The fifth plastic lens L5 is located after the fourth glass lens L4. The fifth plastic lens L5 has a negative refractive power and is formed of a plastic material having at least one surface aspherical. Both surfaces of the fifth plastic lens L5 may be concave. The fifth plastic lens L5 is preferably formed of a plastic material having a high refractive index of 1.6 or more in order to realize high resolution. Reference numeral 251 denotes an object side surface of the fifth plastic lens L5, and 252 denotes an image side surface of the fifth plastic lens L5.

An optical filter 270 may be positioned between the fifth plastic lens L5 and the imaging surface 280. The optical filter 270 may be an infrared filter, a cover glass, or the like.

The wide-angle lens system of the present invention can reduce the manufacturing cost by using only one glass lens (fourth glass lens L4). In addition, the fourth glass lens L4 may be made of a glass lens having an Abbe number of 50 or more, and may have the highest refractive power, thereby minimizing the resolution change due to the temperature change.

The first polymer lens L1, the second plastic lens L2, the third plastic lens L3, and the fifth plastic lens L5 are formed of a plastic material having at least one surface aspheric. The second plastic lens L2 located relatively close to the external environment has the lowest refractive power, thereby minimizing the change in resolution with temperature. The fifth plastic lens L5, which is furthest from the external environment and closest to the imaging surface 280, has a high refractive index of 1.6 or more, thereby increasing the resolution of the lens system.

Thus, the wide-angle lens system of the present invention is composed of a total of five lenses, limiting the use of glass lenses to one sheet, while reducing the manufacturing cost, while realizing a wide-angle high resolution and a wide temperature change (-20 ℃ ~ 80 ℃) also has the advantage that can guarantee the resolution. In addition, the wide-angle lens system of the present invention has the advantage that the image can be captured at an excellent resolution without focusing in the near infrared region (700 ~ 950nm) by implementing a wide-angle high resolution with a total of five lenses.

Hereinafter, a fifth embodiment according to the present wide-angle lens system will be described.

Fifth Example

8A is a diagram showing the configuration of a wide-angle lens system according to the fifth embodiment of the present invention. 8B to 8D are graphs of resolutions according to temperatures of the wide-angle lens system according to the fifth embodiment of the present invention in the visible light region. 8E to 8G are graphs of resolution according to temperature of the wide-angle lens system according to the fifth embodiment of the present invention in the near infrared region.

The following shows design data of the wide-angle lens system according to the fifth embodiment of the present invention.

lens if Radius of curvature thickness Refractive index Abe number Focal length Refractive ability The first lens Front page 55.34301 0.6 1.528208 54 -5.23433 0.287773 The second page 2.623395 2.8 The second lens Front page -4.657147 3.5 1.5324 56.04 30.74566 0.048992 The second page -4.572285 3.7 Third lens Front page -11.4241 1.5 1.5324 56.04 9.634128 0.15635 The second page -3.7013 0.05 Fourth lens Front page 3.1 2.4 1.62041 60.32 2.933051 0.513561 The second page -3.1 0.05 Fifth lens Front page -2.884278 0.63 1.6328 23.35 -3.39018 0.444313 The second page 9.082165 1.145334

Here, the F number is 2.01, the total focal length is 1.5063 mm, and the angle of view is 90 °.

The focal length is the longest of the second plastic lens L2 and the shortest of the fourth glass lens L4. Therefore, the refractive power of the second plastic lens L2 is the lowest, and the refractive power of the fourth glass lens L4 is the highest. If the refractive power of the other lens is higher than the refractive power of the fourth glass lens L4, it becomes undesirable to be a temperature sensitive lens system.

The refractive ability of the first polymer lens L1 satisfies Condition 1 above.

0.01 <| K1 / Kt | <0.5 [Condition 1]

Here, K1 is the refractive power of the first polymer lens L1, and Kt is the refractive power of the entire lens system.

The refractive power of the second plastic lens L2 satisfies Condition 2 above.

0.01 <K2 / Kt | <0.5 [Condition 2]

Here, K2 is the refractive power of the second plastic lens L2, and Kt is the refractive power of the entire lens system.

The refractive power of the third plastic lens L3 satisfies Condition 3 above.

0.01 <| K3 / Kt | <0.5 [Condition 3]

Here, K3 is the refractive power of the third plastic lens L3, Kt is the refractive power of the entire lens system.

The refractive ability of the fourth glass lens L4 satisfies Condition 4 above.

0.4 <| K4 / Kt | <1 [Condition 4]

Here, K4 is the refractive power of the fourth glass lens L4, and Kt is the refractive power of the entire lens system.

The refractive power of the fifth plastic lens L5 satisfies Condition 5 above.

0.4 <| K5 / Kt | <1 [Condition 5]

Here, K5 is the refractive power of the fifth plastic lens L5, and Kt is the refractive power of the entire lens system.

From the above Conditional Expressions 1 to 5, it can be seen that the refractive power of the first polymer lens L1, the second plastic lens L2, and the third plastic lens L3 occupies a low ratio in the refractive power of the entire lens system. In addition, it can be seen that the refractive power of the fourth glass lens L4 and the fifth plastic lens L5 occupies a high ratio in the refractive power of the entire lens system. This is to reduce the change in resolution due to temperature change by providing low refractive power to the first polymer lens L1, the second plastic lens L2, and the third plastic lens L3 which are relatively close to the external environment.

In the present exemplary embodiment, both surfaces of the first polymer lens L1, the second plastic lens L2, the third plastic lens L3, and the fifth plastic lens L5 are formed as aspherical surfaces. Conic constants and aspheric coefficients of the first polymer lens L1, the second plastic lens L2, the third plastic lens L3, and the fifth plastic lens L5 are as follows.

division The first lens The second lens Third lens Fifth lens Front page The second page Front page The second page Front page The second page Front page The second page K -128.651 -0.24417 0 0 0 0 0 43.1979 A4 -0.00011 -0.00016 -0.00222 0.000686 -0.01213 -0.00521 0.023696 0.036255 A6 1.08E-06 6.92E-13 -1.02E-04 5.41E-05 0.000661 0.000427 -0.00181 0.004278 A8 -5.62E-16 1.01E-16 1.83E-05 8.19E-06 -0.00011 0.00028 -0.00094 -0.00103 A10 -3.28E-19 -2.33E-20 3.13E-16 2.92E-16 -0.00018 -3.64E-05 0.000195 8.03E-05

8B, 8C and 8D show graphs of resolution of the lens system at respective temperatures (20 ° C., 80 ° C., −20 ° C.) in the visible range.

In the graph, the color of the line, the straight line, the dotted line, etc., represent the resolution for each position. For example, in the graph, the solid red line is the resolution of light entering the center of the lens, green is the light coming in at 15 ° (half angle), blue is the light coming in at 30 ° (half angle), and purple is 45 ° (half angle). Indicates incoming light. The color of these lines represents the light entering the lens at four representative points (0 °, 15 °, 30 °, 45 °).

8B to 8D, it can be seen that the resolution of the wide-angle lens system at 20 ° C is similarly maintained at 80 ° C and -20 ° C. Therefore, the wide-angle lens system of the present embodiment can reduce the manufacturing cost by limiting the use of glass lenses to one sheet while reducing the total number of lenses. In addition, high resolution of a wide angle can be realized, and resolution can be guaranteed even under a wide range of temperature changes (-20 ° C to 80 ° C).

8E, 8F and 8G show graphs of resolution of the lens system at respective temperatures (20 ° C., 80 ° C., −20 ° C.) in the near infrared region.

8E to 8G, it can be seen that the resolution of the wide-angle lens system at 20 ° C in the near infrared region is sufficiently maintained at 80 ° C and -20 ° C. Therefore, the wide-angle lens system of the present embodiment can guarantee the resolution even in a wide range of temperature changes (-20 ° C. to 80 ° C.) while maintaining excellent resolution without additional focus adjustment even in the near infrared region.

It will be apparent to those skilled in the art that various modifications and variations can be made in the present invention without departing from the spirit and scope of the invention will be.

111, 121, 131, 141, 151: object side
112, 122, 132, 142, 152: upper side
160: aperture
170: optical filter
180: image plane
L1: first glass lens
L2: second plastic lens
L3: third plastic lens
L4: fourth glass lens
L5: fifth plastic lens

Claims (15)

In the wide-angle lens system for visible light and near infrared light,
A first glass lens of a meniscus type having negative refractive power in order from the object side and convex toward the object side;
A second plastic lens of a meniscus type having positive refractive power and concave toward the object and having at least one surface aspherical;
A third plastic lens having positive refractive power and at least one surface being aspherical;
iris;
A fourth glass lens having positive refractive power and double-sided convex;
A fifth plastic lens having negative refractive power and at least one surface being aspherical;
Wide-angle lens system for visible light and near infrared light comprising a. The method of claim 1,
And the first glass lens and the fourth glass lens are spherical both surfaces, and the wide angle lens system for visible light and near infrared light. 3. The method of claim 2,
The fifth plastic lens is a wide-angle lens system for visible light and near infrared light concave on both sides. The method of claim 1,
The fourth glass lens is a wide-angle lens system for visible light and near infrared rays formed of a material of Abbe number 50 or more. The method of claim 1,
The fifth plastic lens is a wide-angle lens system for visible light and near infrared light having a refractive index of 1.6 or more. The method according to any one of claims 1 to 5,
A wide-angle lens system for visible light and near infrared light having the highest refractive power of the fourth glass lens among the lenses. The method according to any one of claims 1 to 5,
A wide-angle lens system for visible light and near infrared light having the lowest refractive power of the second plastic lens among the lenses. The method according to any one of claims 1 to 5,
Wide-angle lens system for visible and near infrared light that meets the following conditions.
0.01 <| K1 / Kt | <0.5
Here, K1 is the refractive power of the first glass lens, Kt is the refractive power of the entire lens system. The method according to any one of claims 1 to 5,
Wide-angle lens system for visible and near infrared light that meets the following conditions.
0.01 <| K2 / Kt | <0.5
Here, K2 is the refractive power of the second plastic lens, Kt is the refractive power of the entire lens system. The method according to any one of claims 1 to 5,
Wide-angle lens system for visible and near infrared light that meets the following conditions.
0.01 <| K3 / Kt | <0.5
Here, K3 is the refractive power of the third plastic lens, Kt is the refractive power of the entire lens system. The method according to any one of claims 1 to 5,
Wide-angle lens system for visible and near infrared light that meets the following conditions.
0.4 <| K4 / Kt | <1
Here, K4 is the refractive power of the fourth glass lens, Kt is the refractive power of the entire lens system. The method according to any one of claims 1 to 5,
Wide-angle lens system for visible and near infrared light that meets the following conditions.
0.4 <| K5 / Kt | <1
Here, K5 is the refractive power of the fifth plastic lens, Kt is the refractive power of the entire lens system. In the wide-angle lens system for visible light and near infrared light,
A first polymer lens having negative refractive power in order from the object side and convex toward the object side and at least one surface being aspherical;
A second plastic lens of a meniscus type having positive refractive power and concave toward the object and having at least one surface aspherical;
A third plastic lens having positive refractive power and at least one surface being aspherical;
iris;
A fourth glass lens having positive refractive power and double-sided convex;
A fifth plastic lens having negative refractive power and at least one surface being aspherical;
Wide-angle lens system for visible light and near infrared light comprising a. The method of claim 13,
The first polymer lens is a wide-angle lens system for visible light and near infrared light manufactured by heat curing or UV irradiation curing. 15. The method of claim 14,
The first polymer lens is a wide-angle lens system for visible light and near infrared rays formed of a material of Abbe number 50 or more.

Images