Long-wave infrared refraction and reflection mixed gun sight objective lens optical system

Abstract

The invention discloses a long-wave infrared refraction and reflection mixed gun sight objective lens optical system, and belongs to the technical field of optical instruments. The system comprises a primary mirror composed of parabolic mirrors and used for collecting and reflecting light; the secondary mirror is a convex reflector, reflects light to the central hole of the primary mirror, then corrects the light through the correction lens, and finally forms a clear image on a focal plane. The lens adopts a refraction and reflection mixed mode to realize imaging, can be integrated with systems of other wavebands, is adaptive to a 17mu m long-wave infrared detector with 640 * 512 pixels, and has the characteristics of simple structure, low distortion, large field of view, small aberration and the like. The invention provides the design method of the long-wave infrared refraction and reflection mixed gun aiming objective lens, the long-wave infrared refraction and reflection mixed gun aiming objective lens can be integrated with optical systems of other wavebands, the system size is reduced, and imaging is clear.

Description

Technical Field

[0001] The invention relates to an optical instrument, in particular to a long-wave infrared refractive-reflective hybrid gun aiming objective optical system. Background Art

[0002] Long-wave infrared rifle sights have night vision capabilities and can quickly identify targets in foggy weather, making them an advantageous piece of equipment for military operations. Traditional long-wave infrared rifle sights generally use a refractive optical structure, which has the disadvantages of being bulky and heavy and difficult to integrate with other band optical systems. The long-wave infrared refractive hybrid rifle sight system reduces the size of the system, and the design of the annular aperture can easily integrate other bands of objective lenses to achieve multi-band simultaneous observation.

[0003] The Chinese patent with publication number CN 105547048 A discloses a technical solution called "a light infrared gun sight". The solution provides a light infrared gun sight that is used in conjunction with the Type 95 gun family, and can complete the observation and aiming of a single person target at about 500m, and can work 24 hours a day. However, the structural design of the lens is relatively complicated and the lens volume is large.

[0004] The Chinese patent with publication number CN 101871747 B discloses a technical solution called "optical system for gun sights". The solution realizes the design of zoom gun sights in the visible light band. The system uses 12 lenses, has a complex structure, and is heavy and bulky. Summary of the invention

[0005] In view of the above shortcomings, this application proposes a design method for a long-wave infrared refractive-reflective hybrid rifle scope optical system, which reduces the volume and weight of the infrared rifle scope optical system. The design of the annular aperture facilitates the integration of the system with rifle scopes of other bands to achieve multi-band imaging.

[0006] To achieve the above-mentioned purpose, the present invention is implemented through the following technical solutions: a long-wave infrared catadioptric hybrid gun aiming objective optical system, characterized in that it includes: a secondary reflector, a third lens, an objective lens surface and a main reflector arranged in sequence from a light source to a detector; the main reflector and the secondary reflector use even-order aspheric reflectors, and the third lens uses a spherical surface.

[0007] Further: the focal length of the lens is 100 (paraxial magnification); the system F# is 1; the system is adaptable to 640×512, 17μm detectors.

[0008] Furthermore: the curvature of the primary reflector is -331.52 mm; the curvature of the secondary reflector is 3251 mm; the center thickness of the third lens is 3 mm, and the curvatures are 56.9, 136.8.

[0009] Furthermore: the center distance between the primary reflector and the secondary reflector is 111.262 mm; the center distance between the secondary reflector and the third lens is 34.22 mm; and the center distance between the third lens and the image plane is 10.6 mm.

[0010] Furthermore: the lens material of the primary reflector and the secondary reflector is aluminum reflector, and the lens material of the third lens is germanium.

[0011] Furthermore: the front surfaces of the primary reflector and the secondary reflector are both coated with a reflective film, and the front and rear surfaces of the third lens are both coated with an anti-reflection film.

[0012] Further: the optical system is adapted to the long wave infrared uncooled detector 640×512, 17μm.

[0013] Further: The design steps are as follows:

[0014] S1, Gaussian design of reflection system;

[0015]

[0016] φ=φ 1 +φ 2 -dφ 1 φ 2 (2)

[0017] The radius of the reflector of the refractive-reflective hybrid optical system is solved by the object-image relationship (1) and the focal length formula (2) of the combined optical system, where f′ is the focal length, r is the radius of the reflector, and Φ is the optical power;

[0018] S2, Optimal design of reflection system;

[0019] By setting the maximum and minimum apertures in the optical design software ZEMAX, the aperture of the reflective surface is set; the aperture size is controlled during the optimization process by combining the two operands DMVA and OPLT.

[0020] S3. Optimal design of the optical system of the catadioptric hybrid mirror;

[0021] The evaluation function is set according to the focal length and aperture requirements, and the optimized design structure of the catadioptric hybrid mirror optical system is obtained after optimization using optical design software;

[0022] The equation for an even-order aspheric surface is:

[0023]

[0024] Among them, R is the surface vertex radius, K is the cone coefficient, A, B, C are the polynomial coefficients of the even-order aspheric surface, y is the radial distance from the optical axis, and z is the arc height value corresponding to the y value.

[0025] The beneficial effects that the present invention can produce include:

[0026] 1) The long-wave infrared refractive-reflective hybrid gun sight objective optical system provided by the present invention is designed as a refractive-reflective hybrid long-wave infrared gun sight objective optical system, using only one lens and two reflectors, which can reduce production costs, and the folded optical path can reduce the system volume.

[0027] 2) Compared with the existing long-wave infrared rifle aiming lens, the long-wave infrared refractive-reflective hybrid rifle aiming lens optical system provided by the present invention adopts a ring-shaped aperture design method. This method only uses a part of the aperture beam, which facilitates the integration of the system with optical systems of other bands.

[0028] 3) The long-wave infrared refractive-reflective hybrid rifle aiming lens optical system provided by the present invention has a wide tolerance limit. Within the radius, thickness and eccentricity range of 0.02 mm, 90% of the samples in the amplitude modulation transfer function can be greater than 22.5%, and the difference from the best image quality is 0.02%. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 This is an optical structure layout diagram of the long-wave infrared catadioptric hybrid rifle aiming objective optical system provided by the present invention;

[0030] Figure 2 The point diagram of the long-wave infrared catadioptric hybrid rifle aiming objective optical system provided by the present invention;

[0031] Figure 3 Amplitude modulation transfer function diagram of the long-wave infrared catadioptric hybrid rifle aiming objective optical system provided by the present invention;

[0032] Figure 4 This is a diagram of field curvature and distortion of the long-wave infrared catadioptric hybrid rifle aiming objective optical system provided by the present invention.

[0033] Legend:

[0034] 1. Secondary reflector; 2. Third lens; 3. Object image plane; 4. Primary reflector. DETAILED DESCRIPTION

[0035] In order to better illustrate the purpose, technical solution and advantages of the present invention, the technical solution of the present invention will be explained in detail and completely with the help of the description in the accompanying drawings. It should be clear that the implementation method introduced only represents one of the various possible implementation forms of the present invention, not all. In general, the component configuration and design method shown and described in the accompanying drawings herein can also be changed and adjusted in various ways according to actual needs.

[0036] The design of the long-wave infrared refractive-reflective hybrid gun sight objective optical system of the present invention comprises the following steps:

[0037] S1, Gaussian design of reflection system;

[0038] S2, Optimal design of reflection system;

[0039] S3. Optimal design of the refracting-reflecting hybrid mirror optical system.

[0040] In step S1, the radius of the reflector of the refractive-reflective hybrid mirror optical system can be solved by the object-image relationship (1) and the focal length formula (2) of the combined optical system, where f′ is the focal length, r is the radius of the reflector, and Φ is the optical focal length.

[0041]

[0042] φ=φ 1 +φ 2 -dφ 1 φ 2 (2)

[0043] In the step S2, the aperture of the reflective surface can be set by setting the maximum aperture and the minimum aperture in the optical design software ZEMAX. The aperture size can be controlled during the optimization process by combining the two operands DMVA and OPLT.

[0044] In the step S3, the evaluation function is set according to the focal length requirements and the aperture requirements, and the optimized design structure of the catadioptric hybrid mirror optical system can be obtained after optimization using optical design software.

[0045] Table 1: Optical structural parameters of the double telecentric uncooled long-wave infrared macro detection optical system of this application

[0046] Surface number radius Numeric thickness 1 <![CDATA[r 1 ]]> Inf Inf 2 <![CDATA[r 2 ]]> Inf 125.58 3 <![CDATA[r 3 ]]> -311.52 -111.26 4 <![CDATA[r 4 ]]> 3251.01 34.22 5 <![CDATA[r 5 ]]> 56.90 3 6 <![CDATA[r 6 ]]> 136.85 10.6

[0047] Table 2: Aspheric coefficients of surfaces 3 and 4

[0048]

[0049] The equation of even-order aspheric surface is:

[0050]

[0051] Among them, R is the surface vertex radius, K is the cone coefficient, A, B, C are the polynomial coefficients of the even-order aspheric surface, y is the radial distance from the optical axis, and z is the arc height value corresponding to the y value.

[0052] In the step S3, the point diagram, amplitude modulation transfer function diagram, field curvature and distortion diagram of the optical system are shown in the attached figure. Figure 2 ,3 , as shown in Figure 4.

[0053] like Figure 1 As shown, a secondary reflector 1, a third lens 2, an object plane 3, and a primary reflector 4 are arranged on the optical path from the object plane to the image plane; both the primary reflector 4 and the secondary reflector 1 use even-order aspherical surfaces; and the third lens 2 uses a spherical surface;

[0054] In this embodiment, the focal length of the lens is 100 (paraxial magnification); the system F# is 1; the system can be adapted to a 640×512, 17μm detector;

[0055] The curvature of the primary reflector is -331.52 mm; the curvature of the secondary reflector is 3251 mm; the center thickness of the third lens is 3 mm, and the curvature is 56.9, 136.8;

[0056] The center distance between the primary reflector and the secondary reflector is 111.262 mm; the center distance between the secondary reflector and the third lens is 34.22 mm; the center distance between the third lens and the image plane is 10.6 mm;

[0057] The lens material of the primary reflector and the secondary reflector is aluminum reflector, and the lens material of the third lens is germanium;

[0058] The front surfaces of the primary reflector and the secondary reflector are both coated with a reflective film, and the front and rear surfaces of the third lens are both coated with an anti-reflection film;

[0059] The lens uses a hybrid refraction-reflection method to achieve imaging, which can be integrated with systems in other bands and is suitable for 640×512 pixel 17μm long-wave infrared detectors.

[0060] Finally, it should be noted that the above is only a preferred embodiment of the present invention and is not intended to limit the present invention. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art can still modify the technical solutions described in the aforementioned embodiments or replace some of the technical features therein by equivalents. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A long-wave infrared catadioptric hybrid rifle aiming lens optical system, characterized in that: The invention comprises the following components which are arranged in sequence from the light source to the detector: a secondary reflector, a third lens, an object mirror and a primary reflector; the primary reflector and the secondary reflector use even-order aspherical reflectors, and the third lens uses a spherical surface.

2. The long-wave infrared catadioptric hybrid rifle aiming objective optical system according to claim 1, characterized in that: The focal length of the lens is 100 (paraxial magnification); the system F# is 1; the system is adaptable to 640×512, 17μm detectors.

3. The long-wave infrared catadioptric hybrid rifle aiming objective optical system according to claim 1, characterized in that: The curvature of the primary reflector is -331.52 mm; the curvature of the secondary reflector is 3251 mm; the center thickness of the third lens is 3 mm, and the curvatures are 56.9 and 136.

8.

4. The long-wave infrared catadioptric hybrid rifle aiming objective optical system according to claim 1, characterized in that: The center distance between the primary reflector and the secondary reflector is 111.262 mm; the center distance between the secondary reflector and the third lens is 34.22 mm; The distance between the third lens and the center of the image plane is 10.6 mm.

5. The long-wave infrared catadioptric hybrid rifle aiming objective optical system according to claim 1, characterized in that: The lens material of the primary reflector and the secondary reflector is aluminum reflector, and the lens material of the tertiary lens is germanium.

6. The long-wave infrared catadioptric hybrid rifle aiming objective optical system according to claim 1, characterized in that: The front surfaces of the primary reflector and the secondary reflector are both coated with reflective films, and the front and rear surfaces of the third lens are both coated with anti-reflection films.

7. The long-wave infrared catadioptric hybrid rifle aiming objective optical system according to claim 1, characterized in that: The optical system is adapted to the long-wave infrared uncooled detector 640×512, 17μm.

8. The long-wave infrared catadioptric hybrid rifle aiming objective optical system according to any one of claims 1 to 7, characterized in that: The design steps are as follows: S1, Gaussian design of reflection system; φ=φ1+φ2-dφ1φ2 (2) The radius of the reflector of the refractive-reflective hybrid optical system is solved by the object-image relationship (1) and the focal length formula (2) of the combined optical system, where f′ is the focal length, r is the radius of the reflector, and Φ is the optical power; S2, Optimal design of reflection system; By setting the maximum and minimum apertures in the optical design software ZEMAX, the aperture of the reflective surface is set; the aperture size is controlled during the optimization process by combining the two operands DMVA and OPLT. S3. Optimal design of the optical system of the catadioptric hybrid mirror; The evaluation function is set according to the focal length and aperture requirements, and the optimized design structure of the catadioptric hybrid mirror optical system is obtained after optimization using optical design software; The equation for an even-order aspheric surface is: Among them, R is the surface vertex radius, K is the cone coefficient, A, B, C are the polynomial coefficients of the even-order aspheric surface, y is the radial distance from the optical axis, and z is the arc height value corresponding to the y value.

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