KR101624873B1 - Camera optical module of athermalization far infrared - Google Patents

Abstract

The present invention relates to a far infrared ray camera optical system, which is a meniscus lens which is formed by molding and which faces the object and which is convex toward the object, has a positive refractive index and both surfaces are aspherical, A first lens which is a diffractive optical element to which a non-heating is applied to minimize focal distance variation during temperature change, including arsenic (As) and selenium (Se), which are chalcogenide optical materials capable of minimizing distance variation; A third surface formed by molding and facing the first lens has a positive refractive index as a convex meniscus lens toward the first lens, both surfaces are aspherical, and the focal length variation of the optical system according to temperature is minimized A second lens including arsenic (As) and selenium (Se), which are chalcogenide optical materials, which can be made non-thermally to minimize focal distance variation during temperature change; And an infrared filter disposed behind the second lens and allowing only far-infrared rays to pass therethrough, the focal length of the first lens and the second lens satisfying the following formula (1) And the dispersion ratio of the lens and the second lens satisfies the following formula (2): " (2) "
The present invention can detect a living or object located at a long distance with a detection distance of 2500 meters and a detection angle of 22 deg or more, and can be applied to various fields (night boundary, method CCTV, etc.) So that it is easy to manufacture and the manufacturing cost is low. Also, it can be used in various temperature ranges.

Description

[0001] The present invention relates to a camera optical module for athermalization far infrared

The present invention relates to a camera optical module for a non-thermal infrared ray, and more particularly, to a camera optical module for a non-thermal infrared ray, which can be applied to various applications, is made non-thermal, and has a low manufacturing cost.

An object having temperature such as a person and an animal generates a self-generated infrared ray and a far-infrared ray. Since a far infrared ray camera shoots infrared rays generated from an object, it is possible to shoot without needing a separate infrared ray source radiating device and can be used in a dark place. However, when a lens designed for visible light is used under infrared conditions, a lens for visible light can not transmit far-infrared rays, and therefore a lens dedicated to far-infrared rays is required.

In general, lenses for exclusive use of far-infrared rays are mostly designed for observation or photographing of objects separated by a short distance (for example, 20 to 30 m).

However, since an object to be observed or photographed using far-infrared rays may be located close to the object, most of the object is located at a distance greater than the object distance. Therefore, the conventional far- have.

In addition, components such as lenses constituting an optical system of a camera are susceptible to temperature changes, and when the temperature range to be operated is widely applied, the focal distance of the optical system changes due to heat shrinkage and expansion of the components, .

As a prior art to the present invention, it is possible to exemplify the registered patent 10-1214601.

It is an object of the present invention to provide a camera optical module for a non-heated infrared camera capable of detecting an organism or an object with a detection distance of 2500 meters and a detection angle of 22 degrees or more.

It is another object of the present invention to provide a camera optical module for a non-heating infrared ray capable of minimizing changes in focal length of an optical system in various temperature environments to maintain the performance of the optical system.

Further, it is an object of the present invention to provide a camera optical module for a non-heating infrared ray which can be applied to various fields (military field, night boundary, security CCTV, automobile, etc.).

It is another object of the present invention to provide a camera optical module for a non-heating infrared camera which can be molded by molding, and is easy to manufacture and low in manufacturing cost.

According to an aspect of the present invention, there is provided a far-infrared ray camera optical system, comprising: a meniscus lens formed by molding and directed toward an object, the meniscus lens being convex toward the object and having a positive refractive index; Which is a chalcogenide optical material capable of minimizing the change of the focal length of the optical system depending on the temperature, including arsenic (As) and selenium (Se) A first lens that is a diffractive optical element; A third surface formed by molding and facing the first lens has a positive refractive index as a convex meniscus lens toward the first lens, both surfaces are aspherical, and the focal length variation of the optical system according to temperature is minimized A second lens including arsenic (As) and selenium (Se), which are chalcogenide optical materials, which can be made non-thermally to minimize focal distance variation during temperature change; And an infrared filter disposed behind the second lens and allowing only far-infrared rays to pass therethrough, the focal length of the first lens and the second lens satisfying the following formula (1) And the dispersion ratio of the lens and the second lens satisfies the following formula (2): " (2) "

[Equation 1]

2.0 <n110 <3.0, 2.0 <n210 <3.0, 20 <v1 <200, 20 <v2 <200, f1 <f2, 1.0 <f2 / f <30, 1.0 <f2 / f1 <3.0

n 110 denotes a refractive index at a wavelength of 10 μm of the first lens,

n108 denotes a refractive index at a wavelength of 8 mu m of the first lens,

n112 denotes a refractive index at a wavelength of 12 mu m of the first lens,

n210 is a refractive index at a wavelength of 10 mu m of the second lens,

n208 is a refractive index at a wavelength of 8 mu m of the second lens,

n212 is a refractive index at a wavelength of 12 mu m of the second lens

&Quot; (2) &quot;

v1 = (n110-1) / (n108-n112), v2 = (n210-1) / (n208-n212)

f is a composite focal length of the first and second lenses at a reference wavelength of 10 mu m,

f1 is the focal length of the first lens at a reference wavelength of 10 mu m,

f2 is the focal length of the second lens at the reference wavelength of 10 mu m

And a diaphragm disposed forward of the first lens.

And a diaphragm disposed on the first surface of the first lens.

The radius of curvature of the first surface of the first lens facing the object side may be smaller than the radius of curvature of the third surface of the second lens facing the first lens.

The edge of the second surface of the first lens facing the second lens can be planarized.

The melting point of the first lens and the second lens may be less than 250 ° C.

The arsenic may comprise 35-45%, and the selenium may comprise 55-65%.

The present invention as described above has a detection distance of 2500 meters and a detection angle of 22 degrees or more. It is easy to manufacture an infrared lens, low manufacturing cost, and can detect an organism or an object.

Further, the present invention can be used in various temperature environments.

In addition, the present invention can be applied to various fields (military field, night boundary, method CCTV, etc.).

Further, the present invention has a structure capable of molding by molding, which is easy to manufacture and low in manufacturing cost.

1 is a cross-sectional view showing a configuration of a camera optical module for a non-heating infrared ray according to an embodiment of the present invention.
Fig. 2 is a view showing an example of a diaphragm arrangement state used in the present invention. Fig.
FIG. 3 is a graph showing spherical aberration, astigmatism, and distortion of the camera module for a non-heating infrared ray shown in FIG. 1;
4A to 4M are graphs showing a temperature-dependent modulation transfer function (MTF) of a camera optical module for a non-heating infrared ray shown in FIG.
FIG. 5 is a graph showing a temperature-dependent performance of a camera optical module for a non-heating infrared ray shown in FIG.
6 is a graph showing the diffraction capability of the first lens of the camera optical module for the non-heating infrared ray shown in Fig.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.

1 is a cross-sectional view showing a configuration of a camera optical module for a non-heating infrared ray according to an embodiment of the present invention.

Referring to FIG. 1, a non-thermal infrared camera optical module 100 according to an embodiment of the present invention includes a first lens L1, a second lens L2, and a far-infrared filter F. In addition, the non-heating infrared camera optical module 100 according to the present invention may further include a diaphragm.

First, the first lens L1, the second lens L2, the far-infrared ray filter F and the diaphragm, which are components of the present invention, can be disposed in a cylindrical barrel (not shown) having a predetermined diameter and length .

A fixing ring or the like for fixing the lens and the filter may be disposed inside the lens barrel.

The detection range of the camera optical module 100 for the non-heating infrared ray according to the present invention may be set to 2500 m, and the detection angle of view may be set to 22 degrees or more. Here, the optical system according to the present invention can measure up to 1000 m based on a person, and can detect up to 2500 m based on an object.

In addition, an effective focal length (EFL) of the camera optical module 100 for the non-heating infrared ray according to the present invention is set to 35 mm. When the effective focal length is set to be short, a wide range can be photographed at a close distance. If the effective focal distance is set long, the angle of view becomes narrow and the photographic range can be photographed. The effective focal lengths of commercially available infrared optical systems are 7.5 mm, 19 mm, 35 mm, 50 mm, and 60 mm. In 35mm optical system, the detection distance is 950m for person and 2550m for object.

In an infrared optical system, a 35 mm optical system can be classified as a medium-distance type. Since the optical system according to the present invention has a detection distance of 2500 m, it is preferable that the lens according to this embodiment is a 35 mm optical system.

The first lens L1, the second lens L2, and the far-infrared filter F are arranged in order from the inner end of the barrel to the other end.

The first lens L1 is a meniscus type convex lens having a convex surface facing the object. The first lens L1 is a convex lens having both surfaces, that is, a first surface R1 on which light is incident and a second surface R2 on which light is transmitted It is aspheric. The first lens L1 has a positive refractive index.

The diameter of the first lens L1 may be larger than the diameter of the second lens L2. It is preferable that the edge of the second surface R2 of the first lens L1 is processed into a flat surface. It is preferable that the concave portion on the second surface R2 of the first lens L1 is larger than the diameter of the second lens L2.

Here, the first lens L1 preferably employs a diffractive optical element (DOE). The diffractive optical element is an optical element that collects light using diffraction by periodic structures rather than refraction or reflection. Since the diffraction optical element is a well-known technique widely known in the field, a detailed description thereof will be omitted.

In the present invention, when the diffractive optical element is applied to the first lens L1, the dispersion ratio and the chromatic aberration can be corrected, and accordingly, the optical design can be optimized with less cost.

The second lens L2 is a convex lens having both surfaces, that is, a third surface R3 on which light is incident and a fourth surface R4 on which light is transmitted are all aspherical surfaces.

The third surface R3 of the second lens L2 is convex with respect to the object to which the non-thermal infrared ray camera optical module 100 is directed, the fourth surface R4 is concave with respect to the direction in which the focal point is formed, The lens L2 is a meniscus type convex lens. The second lens L2 has a positive refractive index.

Here, it is preferable that a glass material having a melting point lower than 250 deg. C is used as the material used for manufacturing the first lens L1 and the second lens L2.

It is preferable that the specifications of the first lens L1 and the second lens L2 satisfy the following equations (1) and (2).

n 110 denotes a refractive index at a wavelength of 10 μm of the first lens,

n108 denotes a refractive index at a wavelength of 8 mu m of the first lens,

n112 denotes a refractive index at a wavelength of 12 mu m of the first lens,

n210 is a refractive index at a wavelength of 10 mu m of the second lens,

n208 is a refractive index at a wavelength of 8 mu m of the second lens,

n212 is a refractive index at a wavelength of 12 mu m of the second lens

f is a composite focal length of the first and second lenses at a reference wavelength of 10 mu m,

f1 is the focal length of the first lens at a reference wavelength of 10 mu m,

f2 is the focal length of the second lens at the reference wavelength of 10 mu m

The first lens L1 and the second lens L2 are preferably formed by a molding process using a predetermined mold. The manufacturing of the lens by molding is well known in the art as disclosed in Japanese Patent Application Laid-Open No. 2001-113041, and thus a detailed description thereof will be omitted.

In addition, in the case of an infrared lens, the first lens L1 and the second lens L2 are made of a chalcogenide material [arsenic (As) and selenium (Se)]. Accordingly, the first lens and the second lens (L1, L2) are athermalized and can be used in a wider temperature range. At this time, the first lens L1 and the second lens L2 are formed of arsenic (35 to 45 mass%), which is a chalcogenide material, which minimizes a change in refractive index according to temperature and minimizes a change in focal distance, To 65% by mass) is used.

The non-thermal infrared camera module 100 according to the present invention may further include a diaphragm 110. The diaphragm 110 is configured such that the degree of aperture of the lens can be changed so that the amount of light incident on the first lens L1 can be adjusted as needed.

The diaphragm 110 may be disposed in front of the first lens L1. At this time, the diaphragm 110 may be disposed at a predetermined distance from the first surface R1 of the first lens L1.

Fig. 2 is a view showing an example of a diaphragm arrangement state used in the present invention. Fig. In Fig. 2, only the first lens L1 and the diaphragm are shown to show the arrangement state of the diaphragm.

Referring to Fig. 2, the diaphragm 110 may be disposed directly on the first surface R1 of the first lens L1. That is, the diaphragm 110 may be disposed in a state of being in close contact with the first surface R1.

When the diaphragm 110 is disposed on the first lens L1, the configuration of the optical system can be simplified, the performance of the optical system can be improved, and the manufacturing cost of the lens barrel can be reduced.

The aperture stop is a well-known technique widely used in this field, so a detailed description thereof will be omitted.

The far-infrared filter F is arranged behind the second lens L2 so that only infrared rays can be transmitted through the light passing through the first lens L1 and the second lens L2. Among infrared rays, infrared rays having a wavelength of 0.75 to 3 占 퐉 are near-infrared rays, infrared rays having a wavelength of 3 to 5 占 퐉 are medium infrared rays, and infrared rays having a wavelength of 8 to 13 占 퐉 are far-infrared rays. Here, it is preferable that the far-infrared filter F transmit far-infrared rays of 8 占 퐉 or more.

The far-infrared filter F has a uniform thickness, and it is preferable that the fifth surface R5 on which light is incident and the sixth surface R6 through which light is incident are preferably planar on both surfaces thereof.

It is preferable that each optical surface of the camera module for the non-heating infrared ray shown in Fig. 1 has the numerical values described in [Table 1], [Table 2] and [Table 3] below.

[Table 1] shows the basic data of the components of the camera optical module for the non-heating infrared ray.

Basic lens data Face number Radius of curvature Face spacing Refractive index Dispersion rate object infinite infinite R1 28.72 (aspherical surface) 9.00 2.7781 160.18 R2 32.36 (aspherical surface) 17.00 R3 32.63 (aspherical surface) 8.50 2.7781 16.018 R4 37.99 (aspherical surface) 11.00 R5 infinite 1.1 4.0032 861.03 R6 infinite 0.9488 Image infinite 0.00

Table 2 shows the aspherical surface coefficient values of the first and second lenses used in the present invention.

Aspherical coefficient K A B C D R1 -0.82523073 -2.29554E-06 -2.10389E-08 -1.14833E-11 -2.17471E-13 R2 1.37062350 -2.15185E-05 -6.76031E-08 -1.83804E-10 2.25032E-13 R3 6.23269926 -3.96961E-05 -2.13007E-07 -3.79949E-09 2.26131E-11 R4 5.58952257 -2.25707E-05 -2.44439E-07 -3.89447E-09 1.94350E-11

Table 3 shows the diffraction coefficient values of the first and second lenses and far-infrared ray filters used in the present invention.

R Coefficient 2 -0.257869E-03 4 -0.369967E-07 6 0.227883E-08 8 -0.593179E-11

The performance of the present invention configured as described above is the same as described with reference to FIG. 3 to FIG.

3 is a graph showing the spherical aberration, astigmatism, and distortion of the camera module for the non-heating infrared ray shown in Fig. 1, respectively.

4A to 4M are graphs showing a temperature-dependent modulation transfer function (MTF) of a camera optical module for a non-heating infrared ray shown in FIG.
Here, 'Modulation Transfer Function (MTF)' means the resolution of the optical module according to the present invention.

4A to 4M, the first and second lenses L1 and L2, which are components of the camera module for a non-heating infrared ray according to the present invention, are subjected to athermalization, The image is operated within a temperature range of 80 占 폚 and stable optical performance is shown in a temperature range of -30 占 폚 to 70 占 폚.

FIG. 5 is a graph showing a temperature-dependent performance of a camera optical module for a non-heating infrared ray shown in FIG.

6 is a graph showing the diffraction capability of the first lens of the camera optical module for the non-heating infrared ray shown in Fig.

The present invention as described above is capable of detecting a living organism or object located at a long distance with a detection distance of 2500 meters and a detection angle of 22 degrees or more and is applicable to various fields (nighttime boundary, method CCTV, etc.) And can be molded by molding, so that it is easy to manufacture and the manufacturing cost is low. Also, it can be used in various temperature ranges.

While the present invention has been described with reference to exemplary embodiments, it is to be understood that the invention is not limited to the disclosed exemplary embodiments, but, on the contrary, is intended to cover various modifications and equivalent arrangements included within the spirit and scope of the appended claims. Accordingly, the true scope of the present invention should be determined by the technical idea of the appended claims.

100: Nonthermalized far infrared camera optical module
L1: first lens
L2: second lens
F: far-infrared filter

Claims (7)

As a far-infrared camera optical system,
The first surface R1 formed by molding and directed toward the object is a meniscus lens convex toward the object and has a positive refractive index and both surfaces are aspherical surfaces to minimize the change of the focal length of the optical system depending on the temperature (As), which is a chalcogenide optical material, is contained in an amount of 35 to 45 mass% and selenium (Se) is contained in a mass ratio of 55 to 65 mass%, and diffraction optics A first lens L1 as an element;
A third surface R3 formed by molding and facing the first lens is a meniscus lens convex toward the first lens L1 and has a positive refractive index and both surfaces are aspherical surfaces, (As), which is a chalcogenide optical material capable of minimizing the focal distance variation, is contained in an amount of 35 to 45 mass%, and the selenium (Se) is contained in 55 to 65 mass% A second lens L2 to which a non-heating is applied to minimize the second lens L2;
A far-infrared ray filter (F) disposed behind the second lens (L2) and passing only the far-infrared rays among the incident rays; And
And a diaphragm (110) arranged in front of the first lens (L1)
The focal lengths of the first lens L1 and the second lens L2 satisfy the following formula (1)
The dispersion ratios of the first lens L1 and the second lens L2 satisfy the following formula (2)
The aspherical surface coefficient values of the first lens (L1) and the second lens (L2) satisfy the following Table 2,
Wherein the diffraction coefficient values of the first lens (L1), the second lens (L2), and the far-infrared filter satisfy the following Table 3.

[Equation 1]
2.0 <n110 <3.0, 2.0 <n210 <3.0, 20 <v1 <200, 20 <v2 <200, f1 <f2, 1.0 <f2 / f <30, 1.0 <f2 / f1 <3.0
n 110 denotes a refractive index at a wavelength of 10 μm of the first lens,
n108 denotes a refractive index at a wavelength of 8 mu m of the first lens,
n112 denotes a refractive index at a wavelength of 12 mu m of the first lens,
n210 is a refractive index at a wavelength of 10 mu m of the second lens,
n208 is a refractive index at a wavelength of 8 mu m of the second lens,
n212 is a refractive index at a wavelength of 12 mu m of the second lens
&Quot; (2) &quot;
v1 = (n110-1) / (n108-n112), v2 = (n210-1) / (n208-n212)
f is a composite focal length of the first and second lenses L1 and L2 at a reference wavelength of 10 mu m,
f1 is the focal length of the first lens L1 at a reference wavelength of 10 mu m,
f2 is the focal length of the second lens L2 at the reference wavelength of 10 mu m

[Table 2]

[Table 3]

The method according to claim 1,
Further comprising a diaphragm (110) disposed in front of the first lens (L1).
delete The method according to claim 1,
Wherein a curvature radius of a first surface R1 of the first lens L1 facing the object side is smaller than a curvature radius of a third surface R3 of the second lens L2 facing the first lens L1 Nonthermalized far infrared camera optical module for far infrared rays. The method according to claim 1,
Wherein the edge of the second surface (R2) of the first lens (L1) facing the second lens (L2) is planarized. The method according to claim 1,
Wherein the melting point of the first lens (L1) and the second lens (L2) is less than 250 占 폚. The method according to any one of claims 1 to 4,
Wherein the arsenic (As) is contained in an amount of 35 to 45 mass%, and the selenium (Se) is contained in an amount of 55 to 65 mass%.

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