WO2018056681A1

WO2018056681A1 - Long-wave infrared camera and camera lens having 21-degree horizontal angle of view

Info

Publication number: WO2018056681A1
Application number: PCT/KR2017/010282
Authority: WO
Inventors: 신승철; 정석현
Original assignee: 주식회사 소모에너지엔테크놀러지
Priority date: 2016-09-20
Filing date: 2017-09-20
Publication date: 2018-03-29
Also published as: CN107843976A; TWI625968B; TW201815152A; HK1246863A1; KR101777661B1

Abstract

The present invention relates to a long-wave infrared camera and camera lens having a 21-degree horizontal angle of view, the lens having a 21-degree horizontal angle of view being made of moldable optical material and having a concave surface (R2) for primary bending of incoming light from a subject, and a convex surface (R3) for secondary bending of the light that has passed through the concave surface (R2), wherein the concave surface (R2) and convex surface (R3) are defined by the relationships in formula 1, table 1 and table 2 of the detailed description.

Description

Long-wavelength infrared cameras with a horizontal angle of view of 21 degrees and lenses for cameras

The present invention relates to a long-wavelength infrared camera and a lens for a camera having a horizontal angle of view of 21 degrees, and more particularly, to a low-wavelength infrared ("LWIR") camera and a lens for a camera that can be used in various security surveillance fields.

The long wavelength infrared rays are light in the wavelength range of 8 µm to 12 µm and include the wavelength range of the infrared rays emitted by humans.

The long wavelength infrared camera is a camera that can detect and capture infrared rays generated by humans or animals at night.

The body temperature of humans and animals is about 310K, and the peak wavelength at 310K of black body radiation is about 8 µm to 12 µm.

Therefore, it is possible to acquire the presence or absence of an image of the human or the animal and the infrared energy of the human or the animal through the long-wavelength infrared camera.

However, in Korea, the development of a long wavelength infrared dedicated lens and a long wavelength infrared camera system is very slow, and most of them depend on imports and are sold at very high prices.

In particular, the conventional infrared camera is made mainly of direct-processing lenses based on germanium (Germanium) lens, the manufacturing cost is high and the manufacturing time was also long.

Therefore, the germanium lens is mainly applied to the military field, and in the civil field, its use is insignificant due to the price problem.

The present invention has been made to solve the above problems of the prior art, the object of the present invention can be applied to the mold molding optical material to lower the production cost compared to the existing germanium lens and to be easily applied to the civil field through mass production The present invention provides a long wavelength infrared camera having a horizontal angle of view of 21 degrees and a lens for a camera.

In order to achieve the above object, a lens for a long wavelength infrared camera having a horizontal angle of view of 21 degrees according to the present invention,

Made of optical material for molding

A concave surface R2 that primarily refracts light incident from a subject; And,

It includes a convex surface (R3) for refracting secondary light passing through the concave surface (R2), the concave surface (R2) and the convex surface (R3) are shown in the following <Equation 1> A lens having a horizontal angle of view of 21 degrees, which is defined by the relationship of Table 2;

TABLE 1

Where k is the conic surface coefficient, A4, A6, A8 and A10 are aspherical coefficients, h is the distance from the optical axis to the concave or convex surface and c represents the center curvature;

TABLE 2

Here, the radius of curvature and the thickness have an allowable range of ± 0.5%;

(Diameter of concave surface R2) / (diameter of convex surface R3) is characterized by being 0.57 (acceptable range of ± 0.5%).

The lens is characterized in that the edge portion extending between the concave surface (R2) and the convex surface (R3) in the direction perpendicular to the optical axis is formed.

(Average thickness TC / diameter of concave surface R2 and convex surface R3) is 0.79 (acceptable range of ± 0.5%), (thickness of edge portion of lens) / (concave surface R2) And the central thickness TC of the convex surface R3) is 0.74 (acceptable range of ± 0.5%).

In addition, a long wavelength infrared camera having a horizontal angle of view of 21 degrees according to the present invention,

iris;

The lens;

An infrared filter spaced apart from the convex surface R3; And,

And a sensor surface for forming an object through light passing through the infrared filter.

The distance between the diaphragm and the concave surface R2 is 0.7 mm ± 0.5%, and the central thickness TC of the concave surface R2 and the convex surface R3 is 6.295 mm ± 0.5%, from the convex surface R3. The distance to the infrared filter is 6.7mm ± 0.5%, the thickness of the infrared filter is 0.65mm ± 0.5%, the distance from the infrared filter to the sensor surface is 1.3mm ± 0.5%, the refractive index of the filter is 3.421 and the dispersion ratio is 2421.0. It features.

According to the present invention having the above-described configuration, it is possible to detect living things or objects with only one lens as the entry-level optical system in the field of security surveillance, and can be applied to various fields (night security surveillance, fire prevention, transformer detection, etc.). There is an advantage.

In addition, according to the present invention, it is made of a structure capable of molding by molding, there is an advantage that the production is easy, mass production is possible, and the manufacturing unit cost is low.

1 is a perspective view of a long wavelength infrared camera having a horizontal angle of view of 21 degrees according to the present invention.

FIG. 2 is a configuration diagram illustrating the optical system structure of FIG. 2.

3 is a light tracking analysis diagram of a long wavelength infrared camera having a horizontal angle of view of 21 degrees according to the present invention.

4 is a graph showing the longitudinal spherical aberration of the long-wavelength infrared camera having a horizontal angle of view of 21 degrees according to the present invention.

5 is an aberration analysis graph of astigmatism of a long-wavelength infrared camera having a horizontal angle of view of 21 degrees according to the present invention.

6 is a graph illustrating distortion of a long-wavelength infrared camera having a horizontal angle of view of 21 degrees according to the present invention.

7 is a graph illustrating an analysis of a Modulation Transfer Function (MTF) indicating a resolution of a long-wavelength infrared camera having a horizontal angle of view of 21 degrees according to the present invention.

FIG. 8 illustrates a spot diagram of a long wavelength infrared camera having a horizontal angle of view of 21 degrees according to the present invention.

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

As shown in FIGS. 1 and 2, the long-wavelength infrared camera 1000 having a horizontal angle of view of 21 degrees according to the present invention includes an aperture 100, a concave surface R2 that primarily refracts light incident from a subject, and A lens 200 including a convex surface R3 for secondarily refracting the light passing through the concave surface R2, an infrared filter 300 spaced apart from the convex surface R3, and the infrared filter And a sensor surface 400 that forms an object through light passing through the 300.

First, the diaphragm 100 disposed in front of the convex surface R3 performs a function of preventing light from entering the optical system of the present invention.

The lens 200 having a horizontal angle of view of 21 degrees is formed of an optical material for molding.

The optical material for molding the mold is made of glass or plastic, and adopts materials that can be composed of various optical systems from ultra-small diameter lenses to medium-diameter lenses by using those having higher refractive index and lens transmission characteristics than similar types of materials on the market. Good to do.

For example, the lens material applied to the optical system design of the present invention is a material for molding such as Ge ₂₇ _.5- Sb ₁₃ _.5- Se _60. A material having a refractive index of 2.5 or more and a transmittance of 65% or more up to a wavelength band of 12 μm may be used. Can be.

When the optical system is composed of the optical material according to the present invention, it is possible to realize a clear image compared to the existing, and it is possible to form a molding by molding, it is possible to construct a security surveillance popular LWIR camera optical system is easy to manufacture and low manufacturing cost.

In addition, the long-wavelength infrared camera 1000 with a horizontal angle of view of 21 degrees according to the present invention proceeded with an optical design of a low-cost type LWIR 1 group applying 6400 pixels (sensor).

The optical system of the present invention has a form advantageous for mold molding by increasing the thickness of the lens center portion and the edge portion 210.

Incidentally, the concave surface R2 and the convex surface R3 of the lens 200 according to the present invention are defined by the following <Equation 1>.

Here, k is a conical surface coefficient, A4, A6, A8 and A10 are aspherical coefficients, h is a distance from an optical axis to a concave or convex surface, and c represents a center curvature.

As shown in Table 1 below, the aspherical surface coefficient is defined to define the concave surface R2 and the convex surface R3.

TABLE 1

In addition, as shown in Table 2 below, the curvature radius RC and the surface thickness ST of the concave surface R2 and the convex surface R3 of the lens 200 were set, and the refractive index n and the dispersion rate v1 were set. ).

The dispersion ratio v1 is defined by the following equation.

v1 = (n110-1) / (n108-n112) <Equation 2>

N110 is a refractive index at a wavelength of 10 μm of a single lens, n108 is a refractive index at a wavelength of 8.0 μm of a single lens, n112 is a refractive index at a wavelength of 12 μm of a single lens,

2.0 <n110 <3.0

TABLE 2

Here, the radius of curvature and the surface thickness may have an allowable range of ± 0.5%.

In particular, (diameter of concave surface R2) / (diameter of convex surface R3) has a value of 0.57 (acceptable range of ± 0.5%), and (thickness of the edge portion of the lens) / (the concave surface R2). ) And the central thickness (TC) of the convex surface (R3) have a value of 0.74 (acceptable range of ± 0.5%), so that the angle of view of 21 degrees can be accurately adjusted.

In addition, since the thickness of the lens center portion and the edge portion is thick, an advantageous form for mold molding is possible.

According to the present invention, the distance between the diaphragm 100 and the concave surface R2 is 0.7 mm ± 0.5%, and the central thickness TC of the concave surface R2 and the convex surface R3 is 6.295 mm ± 0.5%. The distance from the convex surface R3 to the infrared filter 300 is 6.7 mm ± 0.5%, and the thickness of the infrared filter 300 is 0.65 mm ± 0.5%, from the infrared filter 300 to the sensor surface 400. The distance can be set to 1.3 mm ± 0.5%.

When the thickness tolerance is set in the lens 200 of the present invention, the lens 200 may be manufactured within the tolerance of the manufactured lens, thereby manufacturing a lens having a constant optical performance.

In addition, by manufacturing the corner portion of the lens 200 in a round shape, it can be advantageous to the assembly and production of the optical system.

Meanwhile, the refractive index of the infrared filter 300 is 3.421 and the dispersion rate is 2421.0.

Through such conditions, a predetermined angle of view can be obtained, and at the same time, longitudinal spherical aberration, astigmatism, and distortion can be minimized, and a good state can be obtained at a value of MTF (Modulation Transfer Functions) representing resolution.

An exemplary embodiment of a long wavelength infrared camera 1000 having a horizontal angle of view of 21 degrees according to the present invention is described based on the configuration as described above.

First, a lens of a camera optical system for LWIR that can be applied to the 21-degree horizontal view angle lens 200 of the long-wavelength infrared camera is particularly security surveillance field according to the present invention, Ge ₂₇ _.5 -Sb _13.5 -Se ₆₀ consisting of non-oxide Infrared optical glass was applied to mold molding.

In addition, the radius of curvature of the concave surface R2 and the convex surface R3 of the lens 200 is -17.7265 mm (aspherical surface), -8.1644 mm (aspherical surface), and the diameter of the concave surface R2 is 5.78 mm and convex, respectively. The diameter of the surface R3 was set to 10.2 mm.

The thickness of the entire lens 200 was 6.935mm.

For mounting, an edge portion 210 extending from the concave surface R2 and the convex surface R3 is formed perpendicular to the optical axis. In consideration of this, the diameter of the entire lens is set to 15.8 mm.

The length of the edge portion 210 can be appropriately adjusted.

The edge portion of the edge portion 210 is treated with a round of 0.3 ~ 0.6mm.

The concave surface R2 and the convex surface R3 of the lens 200 were formed from the above <Formula 1>, <Table 1> and <Table 2>.

In addition, the center part thickness TC of the concave surface R2 and the convex surface R3 was 6.295 mm, and the edge part thickness of the lens was set to 4.635, respectively.

In addition, the distance between the aperture 100 and the concave surface (R2) is 0.7mm, the distance from the convex surface (R3) to the infrared filter 300 is 6.7mm, the thickness of the infrared filter 300 is 0.65mm, the The distance from the infrared filter 300 to the sensor surface 400 was set to 1.3 mm.

The infrared filter 300 has a refractive index of 3.421 and a dispersion of 2421.0.

In addition, a sensor of the sensor surface 400 may be a 34㎛ sensor of 80 * 80 pixels.

Experiments of FIGS. 3 to 8 were obtained with respect to the long wavelength infrared camera 1000 having the horizontal angle of view of 21 degrees according to the present invention.

3 is an optical trace analysis diagram of a long-wavelength infrared camera having a horizontal angle of view of 21 degrees according to the present invention, and FIG. 4 is a graph illustrating longitudinal spherical abberration of a long-wavelength infrared camera having a horizontal angle of view of 21 degrees according to the present invention. 5 is an aberration analysis graph of astigmatism of a long-wavelength infrared camera having a horizontal angle of view of 21 degrees according to the present invention, and FIG. 6 is a graph showing distortion of a long-wavelength infrared camera having a horizontal angle of view of 21 degrees according to the present invention. FIG. 7 is a graph illustrating an analysis of a Modulation Transfer Function (MTF) indicating the resolution of a long-wavelength infrared camera having a horizontal angle of view of 21 degrees according to the present invention, and FIG. 8 is a spot diagram of a long-wavelength infrared camera having a horizontal angle of view of 21 degrees according to the present invention. diagram).

As shown in FIGS. 3 to 8, the long-wavelength infrared camera having a horizontal angle of view of 21 degrees according to the present invention shows that the values of the images are shown adjacent to the central axis in almost all fields, indicating that the correction state of various aberrations is good. Of course, it indicates that the MTF (optical required performance / resolution) is satisfied.

In addition, the peripheral light quantity ratio of the optical system of the present invention can be secured to 95% or more, the distortion can be limited to within 5% to obtain a clearer image.

Therefore, the present invention is sufficiently possible to apply an optical material for molding a mold such as a non-oxide infrared optical glass, it is possible to lower the production cost compared to the conventional germanium lens and easily applied to the civilian field through mass production.

Claims

Made of optical material for molding

A concave surface R2 that primarily refracts light incident from a subject; And,

It includes a convex surface (R3) for refracting secondary light passing through the concave surface (R2), the concave surface (R2) and the convex surface (R3) are shown in the following <Equation 1> A lens having a horizontal angle of view of 21 degrees, which is defined by the relationship of Table 2;

<Equation 1>

TABLE 1

Where k is the conic surface coefficient, A4, A6, A8 and A10 are aspherical coefficients, h is the distance from the optical axis to the concave or convex surface and c represents the center curvature;

TABLE 2

Here, the radius of curvature and the thickness have an allowable range of ± 0.5%;

(Diameter of concave surface (R2)) / (diameter of convex surface (R3)) is 0.57 (acceptable range of ± 0.5%).
In claim 1,

The lens has a horizontal angle of view of 21 degrees, wherein the lens has an edge portion extending between the concave surface (R2) and the convex surface (R3) in a direction perpendicular to the optical axis.
The method of claim 2,

(Average thickness TC / diameter of concave surface R2 and convex surface R3) is 0.79 (acceptable range of ± 0.5%), (thickness of edge portion of lens) / (concave surface R2) And a central thickness TC of the convex surface R3 is 0.74 (acceptable range of ± 0.5%).
iris;

A lens according to any one of claims 1 to 3;

An infrared filter spaced apart from the convex surface R3; And,

And a sensor surface that forms an image of a subject through light passing through the infrared filter. 21. A long-wavelength infrared camera having a horizontal angle of view of 21 degrees.
The method of claim 4, wherein

The distance between the diaphragm and the concave surface R2 is 0.7 mm ± 0.5%, and the central thickness TC of the concave surface R2 and the convex surface R3 is 6.295 mm ± 0.5%, from the convex surface R3. The distance to the infrared filter is 6.7mm ± 0.5%, the thickness of the infrared filter is 0.65mm ± 0.5%, the distance from the infrared filter to the sensor surface is 1.3mm ± 0.5%, the refractive index of the filter is 3.421 and the dispersion ratio is 2421.0. Long wavelength infrared camera with horizontal angle of view of 21 degrees.