Wide-angle three-dimensional counter-scanning cold-type mid-wave infrared optical system

Abstract

The application discloses a wide-angle three-dimensional anti-scanning cold-type middle-wave infrared optical system, which comprises, in sequence from an object side to an image side, an azimuth-elevation scanning group, a main objective lens group, a horizontal roll scanning group and a relay group; the main objective lens group comprises four lenses, namely a single-crystal germanium lens with negative focal power, a single-crystal silicon lens with negative focal power, a single-crystal silicon lens with positive focal power and a single-crystal germanium lens with positive focal power; the horizontal roll scanning group comprises a half-penta prism and a Schmidt prism; the horizontal roll scanning group is used for eliminating image rotation introduced by azimuth scanning of the azimuth-elevation scanning group and completing horizontal roll scanning; in a clockwise direction, a first working surface of the half-penta prism and a second working surface of the Schmidt prism are perpendicular to an optical path; the relay group comprises three lenses, namely a single-crystal germanium lens with negative focal power, a single-crystal silicon lens with positive focal power and a single-crystal silicon lens with negative focal power. The application realizes 100% cold-stop efficiency, has small volume and weight, simple and stable structure and excellent thermal insensitivity.

Description

Technical Field

[0001] This invention relates to the field of optical technology, and in particular to a wide-angle three-dimensional reverse scanning cooled mid-wave infrared optical system. Background Technology

[0002] Infrared optical systems, as a key component of modern detection technology, offer advantages such as non-contact operation, all-day and all-weather capability, and have been widely applied in military, aerospace, and environmental monitoring fields. While traditional infrared detector technology can achieve infrared imaging of targets, it is often limited by its field of view, making it unable to meet the demands for rapid scanning of wide-angle, large-scale, and multi-dimensional targets. Therefore, the development of wide-angle 3D scanning cooled infrared optical systems is particularly important for achieving the acquisition of three-dimensional information over a large spatial area.

[0003] The wide-angle 3D scanning cooled infrared optical system is a system that combines wide-angle optical design, 3D scanning technology, and a cooled infrared detector. The core design of the wide-angle optical system lies in achieving wide-field coverage through a special optical structure, enabling rapid and seamless capture of infrared radiation information in a wide-area scene. Compared to traditional narrow-field 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 operation. Building upon the wide-angle infrared system, 3D scanning technology further enhances the system's detection efficiency and spatial coverage.

[0004] Wide-angle 3D scanning cooled infrared optical systems achieve comprehensive spatial coverage through azimuth, elevation, and roll angle adjustments. Azimuth scanning adjusts the horizontal viewing angle, suitable for wide-area coverage of targets on the left and right sides; elevation scanning primarily adjusts the vertical angle, suitable for continuous imaging of targets at varying altitudes; roll scanning ensures viewing angle stability in dynamic environments, avoiding image distortion. The combined use of these three scanning methods enables multi-directional, multi-dimensional infrared detection within a single spatial coordinate system, ensuring comprehensive target coverage. This 3D scanning method is particularly important in modern optoelectronic detection, especially suitable for scenarios requiring high-precision positioning and target identification. In the military field, it can be used for panoramic target surveillance and rapid target acquisition, providing precise information support for decision-making. In environmental monitoring, wide-angle scanning technology can detect heat distribution over large areas, applicable to forest fire prevention, marine monitoring, etc. In the aerospace field, the system can be installed on satellite or UAV platforms for aerial reconnaissance and monitoring missions. Furthermore, with the development of artificial intelligence and image processing technologies, the image analysis capabilities of infrared imaging systems are constantly improving, enabling real-time identification and classification of various types of targets, greatly enhancing the intelligence level of infrared systems. With the continuous development of optical design, cooling technology, and scanning control technology, wide-angle 3D scanning cooled infrared optical systems will have even 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 reverse scanning cooled mid-wave infrared optical system that addresses the deficiencies in the prior art.

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

[0007] This invention provides a wide-angle three-dimensional reverse-scan cooled mid-wave infrared optical system, comprising, from object side to image side: an azimuth and elevation 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 mirror;

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

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

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

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

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

[0014] Furthermore, the optical system of the present invention operates in the mid-wave band of 3.7~4.8μm, with an F# of 2; and a staring field of view of 56.1°×46.2°.

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

[0016] Furthermore, in the optical system of the present invention, the entrance pupil is located at the azimuth and elevation scanning group; the exit pupil is located on the cold aperture of the cooled detector, so that the system meets 100% cold aperture 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, in the primary objective lens group of the present invention, the first surface of the lens and the first surface of the lens are designed with high-order aspherical surfaces to correct spherical aberration and distortion; in the relay group, the second surface of the lens is designed with high-order aspherical surfaces to correct spherical aberration of the relay group.

[0019] Furthermore, the materials of the semi-pentaprism and Schmidt prism of the present invention are single-crystal silicon; the roll scanning group uses a combination of prisms to perform roll scanning, which is used to fold the optical path and compress the size of the optical system.

[0020] Furthermore, the repeater group amplification factor of this invention is 0.35. × .

[0021] The beneficial effects of this invention are:

[0022] 1. The wide-angle 3D reverse-scanning cooled mid-wave infrared optical system adopts a secondary imaging structure, achieving 100% cold aperture efficiency. Furthermore, the entrance pupil is positioned at the azimuth and elevation scanning group, facilitating miniaturization of the azimuth and elevation scanning group, reducing size and weight, and resulting in a simple and stable structure. This system uses only conventional germanium and silicon single-crystal infrared materials, exhibiting minimal thermal defocusing within a temperature range of -30℃ to +60℃, demonstrating excellent thermal insensitivity.

[0023] 2. The wide-angle 3D scanning cooled infrared optical system organically combines wide-angle optical design, 3D scanning technology and cooled infrared detector, featuring a large field of view, high sensitivity and all-round coverage, meeting the needs of modern detection technology for large-area, all-weather, all-time high-precision detection.

[0024] 3. The optical system has a compact structure and good imaging quality. Based on a wide-angle infrared system, the addition of three-dimensional scanning technology further enhances the system's detection efficiency and spatial coverage. Attached Figure Description

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

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

[0027] Figure 2 This is a transfer function diagram of the optical system according to an embodiment of the present invention. Detailed Implementation

[0028] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0029] Figure 1 and Figure 2 These are schematic diagrams and transfer function diagrams of the wide-angle three-dimensional reverse-scanning cooled mid-wave infrared optical system described in this invention. The system is characterized by comprising, from the object side to the image side, an azimuth and elevation scanning group 1, a primary objective lens group 2, a roll scanning group 3, and a relay group 4, wherein:

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

[0031] The first element of the main objective lens group 2 is a single-crystal germanium lens 21 with positive optical power, the second element is a single-crystal silicon lens 22 with positive optical power, the third element is a single-crystal silicon lens 23 with negative optical power, and the fourth element is a single-crystal germanium lens 24 with negative optical power. The main function of the main objective lens group is to realize the first imaging of the optical system, reduce the beam size, and reduce the overall size of the roll scanning group 3.

[0032] The roll scanning group 3 consists of a semi-pentaprism 31 and a Schmidt prism 32. The function of the roll scanning group 3 is to eliminate the image rotation introduced during the azimuth scanning of the azimuth and pitch scanning group 2 and to complete the roll scan. The semi-pentaprism and Schmidt prism are made of single-crystal silicon. In a clockwise direction, the first working surface of the semi-pentaprism 31 and the second working surface of the Schmidt prism 32 are perpendicular to the optical path. The imaging beam passes through the semi-pentaprism and Schmidt prism, and the optical path is folded inside the prisms, maximizing the compression of the optical system size and achieving miniaturization. The roll scanning group 3 rotates around the Z-axis to achieve image rotation elimination and roll scanning.

[0033] Relay group 4 consists of three lenses: the first is a single-crystal germanium lens 41 with negative optical power; the second is a single-crystal silicon lens 42 with positive optical power; and the third is a single-crystal silicon lens 43 with negative optical power. The relay group performs secondary imaging, projecting the primary image from the main objective lens group onto the detector target surface. The magnification of 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 for Specific Embodiments

[0036]

[0037] In Table 1, radius of curvature refers to the radius of curvature of each lens surface. Surfaces marked with "*" in the radius of curvature column are aspherical. Thickness or spacing refers to the lens thickness or the distance between adjacent lens surfaces. Material refers to the material used in the lens. Air means that the medium between two lenses is air.

[0038] To achieve better image quality, the system uses four aspherical surfaces. The first surfaces of lens 21 and lens 22 in the primary objective group 2 are designed with high-order aspherical surfaces to correct spherical aberration and distortion. The second surface of lens 41 in the relay group 4 is designed with high-order aspherical surfaces to correct spherical aberration in the relay group.

[0039] Table 2 shows the aspheric coefficient used in specific embodiments.

[0040]

[0041] The equations for aspherical surfaces are defined as follows:

[0042] Practical use has proven that this optical system has a compact structure and good imaging quality. Based on a wide-angle infrared system, the addition of three-dimensional scanning technology further enhances the system's detection efficiency and spatial coverage.

[0043] Figure 2 The graph shows the transfer function of the optical system of this invention at 32 lp / mm, with the horizontal axis representing the number of line pairs per millimeter and the vertical axis representing the contrast ratio.

[0044] In a preferred embodiment of the present invention, the mid-wave operating band of the infrared optical system is 3.7~4.8μm, and the F# is 2. The staring field of view is 56.1°×46.2°; the azimuth and elevation scanning group 1 swings around the X-axis to achieve elevation scanning with a scanning angle of -5° to 20°, and the azimuth and elevation scanning group 1 rotates around the Z-axis to perform azimuth scanning with a scanning angle range of ±30°, thereby achieving fan-shaped imaging of a 60° range of the optical system's visual axis.

[0045] In a preferred embodiment of the present invention, the system entrance pupil is located at the azimuth and elevation scanning group 1, which facilitates the miniaturization design of the azimuth and elevation scanning group and reduces its size and weight; the exit pupil is located on the cold aperture of the cooled detector, so that the system meets the 100% cold aperture efficiency.

[0046] In summary, the wide-angle three-dimensional reverse-scanning cooled mid-wave infrared optical system of this invention consists of an azimuth and elevation scanning group, a main objective lens group, a roll scanning group, and a relay group, sequentially from the object side to the image side. The wide-angle three-dimensional reverse-scanning cooled mid-wave infrared optical system adopts a secondary imaging structure, achieving 100% cold aperture efficiency and placing the entrance pupil at the azimuth and elevation scanning group, which facilitates miniaturization of the azimuth and elevation scanning group, reducing its size and weight, and resulting in a simple and stable structure. The wide-angle three-dimensional reverse-scanning cooled mid-wave infrared optical system uses only conventional germanium single-crystal and silicon single-crystal infrared materials. The optical system exhibits minimal thermal defocusing within a temperature range of -30℃ to +60℃, demonstrating excellent thermal insensitivity.

[0047] It should be understood that the sequence number of each step in the above embodiments does not imply 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 this application.

[0048] It should be understood that those skilled in the art can make improvements or modifications based on the above description, and all such improvements and modifications should fall within the protection scope of the appended claims.

Claims

1. A wide-angle three-dimensional reverse-scanning cooled mid-wave infrared optical system, characterized in that, From the object side to the image side, the sequence includes: azimuth and elevation scanning group (1), main objective lens group (2), roll scanning group (3), and relay group (4); among which: The optical element of the azimuth and elevation scanning group (1) is a plane mirror; The main objective lens group (2) includes four lenses with an optical power combination of "++--", that is, the first lens is a single-crystal germanium lens with positive optical power, the second lens is a single-crystal silicon lens with positive optical power, the third lens is a single-crystal silicon lens with negative optical power, and the fourth lens is a single-crystal germanium lens with negative optical power. The roll scanning group (3) includes a half-pentagonal prism (31) and a Schmidt prism (32); the roll scanning group (3) is used to eliminate the image rotation introduced during the azimuth scanning of the azimuth and pitch scanning group (1) and to complete the roll scanning; in the clockwise direction, the first working surface of the half-pentagonal prism (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 with negative optical power, the second lens is a single-crystal silicon lens with positive optical power, and the third lens is a single-crystal silicon lens with negative optical power; the optical power combination is in the form of "- + -".

2. The wide-angle three-dimensional reverse scanning cooled mid-wave infrared optical system according to claim 1, characterized in that, The azimuth and elevation scanning group (1) is made of single-crystal silicon with a gold-plated reflective film on the surface, reflecting 3μm to 5μm mid-wave infrared spectrum.

3. The wide-angle three-dimensional reverse-scanning cooled mid-wave infrared optical system according to claim 1, characterized in that, When the azimuth and elevation scanning group (1) is at the zero position of the elevation scan, the angle between its normal and the optical axis is 45°; when the elevation scan is at the extreme position, the angle between its normal and the optical axis is 42.5° and 55° respectively.

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

5. The wide-angle three-dimensional reverse scanning cooled mid-wave infrared optical system according to claim 1, characterized in that, The azimuth and elevation scanning group (1) swings around the X-axis to achieve elevation scanning with a scanning angle of -5° to 20°. The azimuth and elevation scanning group (1) rotates around the Z-axis to perform azimuth scanning with a scanning angle range of ±30°, thereby achieving fan-shaped imaging of the 60° range of the optical system's visual axis.

6. The wide-angle three-dimensional reverse scanning cooled mid-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 aperture of the cooled detector, so that the system meets the 100% cold aperture efficiency.

7. The wide-angle three-dimensional reverse-scanning cooled mid-wave infrared optical system according to claim 1, characterized in that, The optical system employs a secondary imaging design, where 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 reverse scanning cooled mid-wave infrared optical system according to claim 1, characterized in that, In the primary objective lens group (2), the second surface of the first lens and the first surface of the second lens are designed with high-order aspherical surfaces to correct spherical aberration and distortion; in the relay group (4), the second surface of the first lens is designed with high-order aspherical surfaces to correct spherical aberration of the relay group.

9. The wide-angle three-dimensional reverse scanning cooled mid-wave infrared optical system according to claim 1, characterized in that, The materials of the semi-pentaprism (31) and Schmidt prism (32) are single-crystal silicon; the roll scanning group (3) uses a combination of prisms to perform roll scanning, which is used to fold the optical path and compress the size of the optical system.

10. The wide-angle three-dimensional reverse-scanning cooled mid-wave infrared optical system according to claim 1, characterized in that, The amplification factor of relay group (4) is 0.

35. × .

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