Wide-angle three-dimensional reverse scanning refrigeration type medium-wave infrared optical system

Abstract

The invention discloses a wide-angle three-dimensional reverse scanning refrigeration type medium-wave infrared optical system, which sequentially comprises an azimuth pitching scanning group, a main objective lens group, a roll scanning group and a relay group from an object space to an image space, wherein the main objective lens group comprises four lenses, namely a monocrystalline germanium lens with negative focal power, a monocrystalline silicon lens with negative focal power, a monocrystalline silicon lens with positive focal power and a monocrystalline germanium lens with positive focal power; the roll scanning group comprises a semi-pentaprism and a Schmidt prism; the roll scanning group is used for eliminating image rotation introduced during azimuth scanning of the azimuth pitching scanning group and completing roll scanning; in the clockwise direction, the first working face of the half pentaprism and the second working face of the Schmidt prism are perpendicular to the light path. And the relay group comprises three lenses, namely a monocrystalline germanium lens with negative focal power, a monocrystalline silicon lens with positive focal power and a monocrystalline silicon lens with negative focal power. According to the invention, 100% cold diaphragm efficiency is realized, the size and weight are small, the structure is simple and stable, and the thermal insensitivity performance is excellent.

Description

Technical Field

[0001] The invention relates to the field of optical technology, and in particular to a wide-angle three-dimensional back-scanning refrigerated medium-wave infrared optical system. Background Art

[0002] As a key component of modern detection technology, infrared optical systems have the advantages of non-contact, all-day and all-weather operation, and have been widely used in military, aerospace, environmental monitoring and other fields. Although traditional infrared detector technology can achieve infrared imaging of targets, it is often unable to meet the needs of rapid scanning of wide-angle, large-range, and multi-dimensional targets due to the limitations of the field of view. In order to achieve three-dimensional information collection in a large range of space, the research and development of wide-angle three-dimensional scanning refrigerated infrared optical systems is particularly important.

[0003] The wide-angle 3D scanning cooled infrared optical system is a system that combines wide-angle optical design, 3D scanning technology and cooled infrared detectors. The core design of the wide-angle optical system is to achieve coverage of a wide range of viewing angles through a special optical structure, so as to quickly and seamlessly capture infrared radiation information in a wide-area scene. Compared with traditional narrow-viewing angle optical systems, the wide-angle system reduces the need for multiple scans and improves imaging efficiency by covering a larger field of view in a single imaging. On the basis of the wide-angle infrared system, the 3D scanning technology further improves the detection efficiency and spatial coverage capability of the system.

[0004] The wide-angle three-dimensional scanning refrigerated infrared optical system achieves full coverage of space through angle adjustment in three directions: azimuth, pitch and roll. Azimuth scanning is used for horizontal viewing angle adjustment, which is suitable for large-scale coverage of targets on the left and right sides; pitch scanning is mainly used for vertical adjustment, which is suitable for continuous imaging of high and low targets; roll scanning can ensure the stability of viewing angle in a dynamic environment and avoid imaging distortion. The comprehensive use of the three scanning methods can realize multi-directional and multi-dimensional infrared detection in a spatial coordinate system to ensure full coverage of the target. This three-dimensional scanning method is particularly important in modern optoelectronic detection, especially for scenes requiring high-precision positioning and target identification. In the military field, it can be used to achieve panoramic monitoring and rapid locking of targets, providing accurate information support for decision-making. In environmental monitoring, wide-angle scanning technology can detect heat distribution in a large area, which is used in forest fire prevention, ocean monitoring, etc. In the aerospace field, the system can be installed on satellites or drone platforms for aerial reconnaissance and monitoring tasks. In addition, with the development of artificial intelligence and image processing technology, the image analysis capability of infrared imaging systems has been continuously improved, and they can identify and classify various types of targets in real time, greatly improving the intelligence level of infrared systems. With the continuous development of optical design, refrigeration technology and scanning control technology, wide-angle 3D scanning refrigerated infrared optical systems will have broader application prospects and development potential in the future. Summary of the invention

[0005] The technical problem to be solved by the present invention is to provide a wide-angle three-dimensional back-scanning refrigerated medium-wave infrared optical system in view of the defects in the prior art.

[0006] The technical solution adopted by the present invention to solve its technical problem is:

[0007] The present invention provides a wide-angle three-dimensional reverse scanning refrigeration type medium-wave infrared optical system, which comprises, from the object side to the image side, an azimuth pitch scanning group, a main objective lens group, a roll scanning group and a relay group; wherein:

[0008] The optical element of the azimuth and elevation scanning group is a plane reflector;

[0009] The main objective lens group includes four lenses, and the focal power combination is "--++", that is, the first lens is a single crystal germanium lens with negative focal power, the second lens is a single crystal silicon lens with negative focal power, the third lens is a single crystal silicon lens with positive focal power, and the fourth lens is a single crystal germanium lens with positive focal power;

[0010] The roll scanning group includes a half pentaprism and a Schmidt prism; the roll scanning group is used to eliminate the image rotation introduced by the azimuth pitch scanning group during azimuth scanning and to complete the roll scanning; in the clockwise direction, the first working surface of the half pentaprism and the second working surface of the Schmidt prism are perpendicular to the optical path;

[0011] The relay group includes three lenses, the first one is a single crystal germanium lens with negative optical power, the second one is a single crystal silicon lens with positive optical power, and the third one is a single crystal silicon lens with negative optical power; the optical power combination is in the form of "-+-".

[0012] Furthermore, the material of the azimuth and elevation scanning group of the present invention is single crystal silicon, and a gold reflective film is plated on the surface to reflect the 3μm to 5μm medium-wave infrared spectrum.

[0013] Furthermore, when the azimuth pitch scanning group of the present invention is at the pitch scanning zero position, the angle between its normal and the optical axis is 45°; when the pitch scanning is at the extreme position, the angles between the normal and the optical axis are 42.5° and 55° respectively.

[0014] Furthermore, the medium-wave working band of the optical system of the present invention is 3.7-4.8 μm, F# is 2, and the staring field of view is 56.1°×46.2°.

[0015] Furthermore, the azimuth pitch scanning group of the present invention swings around the X-axis to achieve pitch scanning, with a scanning angle of -5° to 20°, and the azimuth pitch scanning group rotates around the Z-axis to perform azimuth scanning, with a scanning angle range of ±30°, to achieve fan-shaped area scanning imaging within a 60° range of the optical system's visual axis.

[0016] Furthermore, the entrance pupil of the optical system of the present invention is located at the azimuth and elevation scanning group; the exit pupil is located on the cold stop of the cooling detector, so that the system meets 100% cold stop efficiency.

[0017] Furthermore, the optical system of the present invention adopts a secondary imaging design, wherein the primary imaging plane is located between the main objective lens group and the roll scanning group, and the secondary imaging plane is located on the system image plane.

[0018] Furthermore, the first lens surface and the first lens surface in the main objective lens group of the present invention adopt a high-order aspheric surface design to correct spherical aberration and distortion; the second lens surface in the relay group adopts a high-order aspheric surface design to correct the spherical aberration of the relay group.

[0019] Furthermore, the material of the half pentaprism and the Schmidt prism of the present invention is single crystal silicon; the roll scanning group uses a combined prism to perform roll scanning, which is used to fold the optical path and compress the size of the optical system.

[0020] Furthermore, the magnification of the relay group of the present invention is 0.35 × .

[0021] The beneficial effects produced by the present invention are:

[0022] 1. The wide-angle 3D reverse-scanning refrigerated medium-wave infrared optical system adopts a secondary imaging structure, which not only achieves 100% cold aperture efficiency, but also sets the entrance pupil at the azimuth and elevation scanning group, which is conducive to the miniaturization design of the azimuth and elevation scanning group, reducing the volume and weight, and the structure is simple and stable. The wide-angle 3D reverse-scanning refrigerated medium-wave infrared optical system only uses conventional germanium single crystal and silicon single crystal infrared materials. The optical system has small thermal defocusing in the temperature range of -30℃ to +60℃ and excellent thermal insensitivity.

[0023] 2. The wide-angle three-dimensional scanning cooled infrared optical system organically combines wide-angle optical design, three-dimensional scanning technology and cooled infrared detectors. It has the characteristics of large field of view, high sensitivity and all-round coverage, meeting the needs of modern detection technology for large-scale, all-weather and all-day high-precision detection.

[0024] 3. The optical system has a compact structure and good imaging quality. Based on the wide-angle infrared system, the optical system adds three-dimensional scanning technology to further improve the system's detection efficiency and spatial coverage capabilities. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] The present invention will be further described below with reference to the accompanying drawings and embodiments, in which:

[0026] Figure 1 is a schematic diagram of an optical system according to an embodiment of the present invention;

[0027] Figure 2 Graph showing the transfer function of an optical system according to an embodiment of the present invention. DETAILED DESCRIPTION

[0028] In order to make the purpose, technical solution and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0029] Figure 1 and Figure 2 They are respectively a schematic diagram and a transfer function diagram of the wide-angle three-dimensional reverse scanning refrigerated medium-wave infrared optical system of the present invention. It is characterized in that the optical system is composed of an azimuth pitch scanning group 1, a main objective lens group 2, a roll scanning group 3 and a relay group 4 from the object side to the image side, wherein:

[0030] The optical element of the azimuth and elevation scanning group 1 is a plane reflector made of single crystal silicon with a gold reflective film on the surface, reflecting the 3μm to 5μm medium-wave infrared spectrum; when the elevation scanning is at zero position, the angle between its normal and the optical axis is 45°; Figure 1As shown, the azimuth pitch scanning group 1 swings around the X-axis to achieve pitch scanning, with a scanning angle of -5° to 20°. When the pitch scanning is at the extreme position, the angles between the normal line of the reflector and the optical axis are 42.5° and 55° respectively; the azimuth pitch scanning group 1 rotates around the Z-axis to perform azimuth scanning, with a scanning angle range of ±30°, to achieve fan-shaped area scanning imaging within a 60° range of the optical system visual axis;

[0031] The first lens of the main objective lens group 2 is a single crystal germanium lens 21 with negative optical power, the second lens is a single crystal silicon lens 22 with negative optical power, the third lens is a single crystal silicon lens 23 with positive optical power, and the fourth lens is a single crystal germanium lens 24 with positive optical power; the main function of the main objective lens group is to realize the first imaging of the optical system, shrink the light beam, and reduce the external dimensions of the rolling scanning group 3;

[0032] The roll scanning group 3 is composed of a half pentaprism 31 and a Schmidt prism 32. The function of the roll scanning group 3 is to eliminate the image rotation introduced by the azimuth pitch scanning group 2 during azimuth scanning and to complete the roll scanning. The half pentaprism and the Schmidt prism are made of single crystal silicon. In the clockwise direction, the first working surface of the half pentaprism 31 and the second working surface of the Schmidt prism 32 are perpendicular to the optical path. The imaging light beam passes through the half pentaprism and the Schmidt prism, and the optical path is folded inside the prism, which compresses the size of the optical system to the greatest extent and realizes a miniaturized design; the roll scanning group 3 rotates around the Z axis to achieve image rotation elimination and roll scanning.

[0033] The relay group 4 consists of three lenses, the first lens is a single crystal germanium lens 41 with negative focal length, the second lens is a single crystal silicon lens 42 with positive focal length, and the third lens is a single crystal silicon lens 43 with negative focal length. The relay group completes the secondary imaging and images the primary image formed by the main objective lens group onto the detector target surface. The magnification of the relay group 4 is 0.35. × .

[0034] The specific design parameters of the optical system are shown in Table 1.

[0035] Table 1 Optical system design parameters of specific embodiments

[0036]

[0037] In Table 1, the radius of curvature refers to the radius of curvature of each lens surface, and the surface marked with "*" in the radius of curvature column is an aspherical surface. Thickness or interval refers to the thickness of the lens or the distance between adjacent lens surfaces, material refers to the material used for the lens, and air refers to the medium between the two lenses being air.

[0038] In order to enable the system to obtain better image quality, four aspherical surfaces are used in the system. The first surface of lens 21 and the first surface of lens 22 in the main objective lens group 2 adopt high-order aspherical surface design to correct spherical aberration and distortion; the second surface of lens 41 in the relay group 4 adopts high-order aspherical surface design to correct the spherical aberration of the relay group.

[0039] Table 2 Aspheric coefficients used in specific embodiments

[0040] surface c k A B C S4 -0.035 0 -6.75E-06 2.44E-09 -8.63E-12 S5 0.007 0 -5.77E-06 3.17E-09 -8.32E-13 S10 0.031 0 -3.08E-06 2.76E-08 -8.49E-11 S16 0.0176 0 4.62E-07 7.45E-11 2.03E-14

[0041] The aspheric equation is defined as follows:

[0042]

[0043] The present invention has been proved through actual use that the optical system has a compact structure and good imaging quality. The optical system is based on a wide-angle infrared system, and the addition of three-dimensional scanning technology further improves the detection efficiency and spatial coverage capability of the system.

[0044] Figure 2 This is a transfer function curve of the optical system of the present invention at 32lp / mm, wherein the horizontal axis is the number of line pairs per millimeter, and the vertical axis is the contrast value.

[0045] In a preferred embodiment of the present invention, the infrared optical system has a working wavelength band of 3.7 to 4.8 μm and an F# of 2. The staring field of view is 56.1°×46.2°; the azimuth pitch scanning group 1 swings around the X-axis to achieve pitch scanning, with a scanning angle of -5° to 20°, and the azimuth pitch scanning group 1 rotates around the Z-axis to perform azimuth scanning, with a scanning angle range of ±30°, to achieve fan-shaped area scanning imaging within a 60° range of the optical system visual axis.

[0046] In a preferred embodiment of the present invention, the entrance pupil of the system is located at the azimuth-pitch scanning group 1, which is conducive to the miniaturized design of the azimuth-pitch scanning group and reduces the volume and weight; the exit pupil is located on the cold aperture stop of the cooling detector, so that the system meets 100% cold aperture stop efficiency.

[0047] In summary, the wide-angle three-dimensional reverse scanning refrigerated medium-wave infrared optical system of the embodiment of the present invention is composed of an azimuth pitch scanning group, a main objective lens group, a roll scanning group, and a relay group from the object side to the image side. The wide-angle three-dimensional reverse scanning refrigerated medium-wave infrared optical system adopts a secondary imaging structure, which not only achieves 100% cold aperture efficiency, but also sets the entrance pupil at the azimuth pitch scanning group, which is conducive to the miniaturization design of the azimuth pitch scanning group, reduces the volume and weight, and has a simple and stable structure. The wide-angle three-dimensional reverse scanning refrigerated medium-wave infrared optical system only uses conventional germanium single crystal and silicon single crystal infrared materials. The optical system has small thermal defocus in the temperature range of -30℃ to +60℃ and excellent thermal insensitivity.

[0048] It should be understood that the size of the serial numbers of the steps in the above embodiments does not mean the order of execution. The execution order of each process should be determined by its function and internal logic, and should not constitute any limitation on the implementation process of the embodiments of the present application.

[0049] It should be understood that those skilled in the art can make improvements or changes based on the above description, and all these improvements and changes should fall within the scope of protection of the appended claims of the present invention.

Claims

1. A wide-angle three-dimensional backscanning refrigerated medium-wave infrared optical system, characterized in that: From the object side to the image side, it includes: an azimuth pitch scanning group (1), a main objective lens group (2), a roll scanning group (3) and a relay group (4); wherein: The optical element of the azimuth and elevation scanning group (1) is a plane reflector; The main objective lens group (2) includes four lenses, and the optical power combination is "--++", that is, the first lens is a single crystal germanium lens (21) with negative optical power, the second lens is a single crystal silicon lens (22) with negative optical power, the third lens is a single crystal silicon lens (23) with positive optical power, and the fourth lens is a single crystal germanium lens (24) with positive optical power; The roll scanning group (3) comprises a half pentaprism (31) and a Schmidt prism (32); the roll scanning group (3) is used to eliminate the image rotation introduced by the azimuth-pitch scanning group (2) during azimuth scanning and to complete the roll scanning; in a clockwise direction, the first working surface of the half pentaprism (31) and the second working surface of the Schmidt prism (32) are perpendicular to the optical path; The relay group (4) includes three lenses, the first lens is a single crystal germanium lens (41) with negative optical power, the second lens is a single crystal silicon lens (42) with positive optical power, and the third lens is a single crystal silicon lens (43) with negative optical power; the optical power combination is in the form of "-+-".

2. The wide-angle three-dimensional back-scanning refrigerated medium-wave infrared optical system according to claim 1, characterized in that: The material of the azimuth and elevation scanning group (1) is single crystal silicon, the surface of which is coated with a gold reflective film, which reflects a 3μm to 5μm medium wave infrared spectrum.

3. The wide-angle three-dimensional back-scanning refrigerated medium-wave infrared optical system according to claim 1, characterized in that: When the azimuth elevation scanning group (1) is at the elevation scanning zero position, the angle between its normal line and the optical axis is 45°; when the elevation scanning is at the elevation scanning extreme position, the angles between its normal line and the optical axis are 42.5° and 55° respectively.

4. The wide-angle three-dimensional back-scanning refrigerated medium-wave infrared optical system according to claim 1, characterized in that: The medium-wave operating band of the optical system is 3.7 to 4.8 μm, with an F# of 2; the staring field of view is 56.1°×46.2°.

5. The wide-angle three-dimensional back-scanning refrigerated medium-wave infrared optical system according to claim 1, characterized in that: The azimuth pitch scanning group (1) swings around the X axis to achieve pitch scanning, with a scanning angle of -5° to 20°. The azimuth pitch scanning group (1) rotates around the Z axis to perform azimuth scanning, with a scanning angle range of ±30°, thereby achieving fan-shaped area scanning imaging within a 60° range of the optical system visual axis.

6. The wide-angle three-dimensional back-scanning refrigerated medium-wave infrared optical system according to claim 1, characterized in that: The entrance pupil of the optical system is located at the azimuth and elevation scanning group (1); the exit pupil is located on the cold stop of the cooling detector, so that the system meets 100% cold stop efficiency.

7. The wide-angle three-dimensional back-scanning refrigerated medium-wave infrared optical system according to claim 1, characterized in that: The optical system adopts a secondary imaging design, in which the primary imaging plane is located between the main objective lens group and the roll scanning group, and the secondary imaging plane is located on the system image plane.

8. The wide-angle three-dimensional back-scanning refrigerated medium-wave infrared optical system according to claim 1, characterized in that: The first surface of the lens (21) and the first surface of the lens (22) in the main objective lens group (2) are designed with high-order aspheric surfaces for correcting spherical aberration and distortion; the second surface of the lens (41) in the relay group (4) is designed with high-order aspheric surfaces for correcting the spherical aberration of the relay group.

9. The wide-angle three-dimensional back-scanning refrigerated medium-wave infrared optical system according to claim 1, characterized in that: The materials of the half pentaprism (31) and the Schmidt prism (32) are single crystal silicon; the rolling scanning group (3) uses a combined prism method to perform rolling scanning, which is used to fold the optical path and compress the size of the optical system.

10. The wide-angle three-dimensional back-scanning refrigerated medium-wave infrared optical system according to claim 1, characterized in that: Relay group (4) magnification is 0.35 × .

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