Compact coaxial turn-back type three-waveband multifunctional common-aperture optical system

Abstract

The invention discloses a compact coaxial turn-back type three-waveband multifunctional common-aperture optical system. Belongs to the technical field of photoelectricity, and particularly relates to the technical field of compact coaxial turn-back type three-waveband common-caliber photoelectricity. The problem that an existing aperture-dividing type optical system is difficult to miniaturize and light and has chromatic aberration is solved. The device comprises a coaxial turn-back type afocal objective lens, a laser emission light path, a short-wave imaging light path and a medium-wave imaging light path, a laser beam emitted by a laser emission light path is emitted to a target through a coaxial turn-back type afocal objective lens, the target reflects the laser beam and a short-wave infrared beam to the coaxial turn-back type afocal objective lens, and meanwhile, the target radiates a medium-wave infrared beam to the coaxial turn-back type afocal objective lens; the coaxial turn-back type afocal objective reflects the laser beam and the short-wave infrared beam to the short-wave imaging light path for imaging, and the coaxial turn-back type afocal objective reflects the medium-wave infrared beam to the medium-wave imaging light path for imaging.

Description

Technical Field

[0001] The invention belongs to the field of optoelectronic technology, and in particular relates to the field of compact coaxial foldback three-band common aperture optoelectronic technology. Background Art

[0002] With the rapid development of science and technology and increasingly complex application scenarios, military reconnaissance, camouflage identification, environmental monitoring, geological exploration and many other fields have put forward higher requirements for the integrity and accuracy of information acquisition. In these fields, the shortcomings of single-band imaging that can only reflect one aspect of the physical characteristics of the target are becoming increasingly prominent and can no longer meet the diverse actual needs.

[0003] Since the optical characteristics of targets in different spectral bands are obviously different, multi-band image fusion technology came into being. This technology integrates image information from multiple bands to achieve more accurate and comprehensive understanding of targets and achieve all-weather, wide coverage, and high-resolution target observation. For example, medium-wave infrared can use the temperature difference between the target and the background to accurately detect and identify targets at night; short-wave infrared has the ability to penetrate smoke and can obtain clear image details in complex environments, providing strong support for accurate analysis; lasers can achieve precise aiming and guidance of targets, and short-wave infrared can also detect laser spots within the short-wave band. The combination of the three can efficiently obtain the shape, position, and motion status information of distant targets.

[0004] In order to meet the needs of long-distance target detection, it is inevitable to increase the aperture and focal length of the optical system. Large-aperture, multi-band, lightweight and miniaturized optoelectronic payloads have become the current development trend. The aperture-type imaging system is a common multi-band imaging solution, which simply combines multiple independent single-band optical systems. However, this imaging system has many disadvantages due to its distributed structure. In addition to its large size, it is extremely difficult to achieve miniaturization and lightness, which seriously affects the mobility of the system and greatly limits its application field, making it difficult to directly apply it to military reconnaissance, camouflage identification, environmental monitoring, geological exploration and other fields with strict requirements on equipment performance and imaging quality. In addition to increasing the difficulty of operators, there is also a significant color difference problem. Due to the differences in optical materials, design structures and imaging principles of each single-band optical system, when performing multi-band image fusion, color inconsistency is likely to occur between images of different bands, which makes the color reproduction of the image poor after synthesis, resulting in the distortion of the true color characteristics of the target object, which greatly affects the accurate identification and analysis of the target, and further restricts the application of the system in the above-mentioned fields with extremely high requirements for image quality. Summary of the invention

[0005] In order to solve the problems of difficulty in miniaturization, lightweight and chromatic aberration of existing divided-aperture optical systems, the present invention provides a compact coaxial reentrant three-band multifunctional common-aperture optical system, which adopts a coaxial reentrant afocal objective lens with a rear optical path structure to achieve a common aperture of laser, short-wave infrared and medium-wave infrared and an integrated optical design of laser emission and reception, thereby improving the system's target detection, positioning and aiming, and laser guidance performance; at the same time, the coaxial reentrant afocal objective lens can correct chromatic aberration in the imaging process by introducing multi-spectral materials.

[0006] The compact coaxial foldback three-band multifunctional common aperture optical system comprises: Coaxial folding afocal objective lens, laser emission optical path, short-wave imaging optical path and medium-wave imaging optical path; The laser emission optical path emits a laser beam through a coaxial reentrant afocal objective lens to a target, the target reflects the laser beam and a short-wave infrared beam to the coaxial reentrant afocal objective lens, and at the same time the target radiates a medium-wave infrared beam to the coaxial reentrant afocal objective lens, the coaxial reentrant afocal objective lens reflects the laser beam and the short-wave infrared beam to the short-wave imaging optical path for imaging, and the coaxial reentrant afocal objective lens reflects the medium-wave infrared beam to the medium-wave imaging optical path for imaging; The coaxial folding afocal objective lens comprises: a primary mirror, a secondary mirror, a multi-band collimating lens assembly and a first reflecting mirror; The laser emission optical path includes: a laser light source, a collimating beam expansion component, a second beam splitter and a first beam splitter; The short-wave imaging optical path includes: a first beam splitter, a second beam splitter, a short-wave infrared imaging component and a short-wave infrared detector target surface; The medium-wave imaging optical path includes: a first beam splitter, a medium-wave infrared imaging component and a medium-wave infrared detector target surface.

[0007] Furthermore, the coaxial reentrant afocal objective lens includes a coaxial output optical path and a coaxial incident optical path; in the coaxial output optical path, the laser light beam emitted by the laser emission optical path passes through the first reflector, the multi-band collimating lens assembly, the secondary mirror and the primary mirror in sequence before being emitted to the target; in the coaxial incident optical path, the laser light beam, the short-wave infrared light beam and the medium-wave infrared light beam received by the primary mirror pass through the primary mirror, the secondary mirror, the multi-band collimating lens assembly and the first reflector in sequence before being emitted to the first beam splitter; the image-side focal points of the primary mirror and the secondary mirror coincide with the object-side focal point of the multi-band collimating lens assembly.

[0008] Furthermore, in the multi-band collimating lens assembly, the incident light beam passes through a multi-band collimating first lens, a multi-band collimating second lens, a multi-band collimating third lens and a multi-band collimating fourth lens in sequence; the material of each lens in the multi-band collimating lens assembly includes multi-spectral zinc sulfide, calcium fluoride and spinel; The primary mirror has a hole in the center, and its reflecting surface is a concave aspheric surface; the reflecting surface of the secondary mirror is a convex aspheric surface; the multi-band collimating lens assembly has a positive optical focal length and is arranged between the secondary mirror and the first reflecting mirror; the multi-band collimating lens assembly is arranged on the horizontal line where the hole in the center of the primary mirror is located; the first reflecting mirror is placed at 45° to the vertical plane.

[0009] Furthermore, in the laser emission optical path, the laser light beam emitted by the laser light source passes through the collimating beam expander assembly, the second beam splitter and the first beam splitter in sequence and then emerges to the coaxial folding afocal objective lens.

[0010] Further, in the collimation and beam expansion assembly, the laser beam passes through the laser collimation and beam expansion first lens, the laser collimation and beam expansion second lens, the laser collimation and beam expansion third lens, the laser collimation and beam expansion fourth lens, the laser collimation and beam expansion fifth lens, the laser collimation and beam expansion sixth lens and the laser collimation and beam expansion seventh lens in sequence, and then is emitted to the second beam splitter; The first laser collimation and beam expansion lens, the fourth laser collimation and beam expansion lens, the sixth laser collimation and beam expansion lens and the seventh laser collimation and beam expansion lens are meniscus spherical lenses with positive optical focal length; the second laser collimation and beam expansion lens and the fifth laser collimation and beam expansion lens are biconcave spherical lenses with negative optical focal length; the third laser collimation and beam expansion lens is a biconvex spherical lens with positive optical focal length.

[0011] Furthermore, in the short-wave imaging optical path, the laser beam and the short-wave infrared beam reflected by the coaxial folding afocal objective lens are reflected by the first beam splitter, and then separated into a laser beam and a short-wave infrared beam by the second beam splitter. The short-wave infrared beam is then emitted to the target surface of the short-wave infrared detector for imaging through the short-wave infrared imaging component; the laser beam is emitted into the laser light source; The first beam splitter is arranged between the coaxial folding afocal objective lens and the medium-wave infrared imaging component in the longitudinal direction, and is used to decompose the incident light beam into a medium-wave infrared beam, a short-wave infrared beam and a laser beam. The first beam splitter is used to transmit the medium-wave infrared beam and reflect the short-wave infrared beam and the laser beam; the second beam splitter is arranged between the first beam splitter and the short-wave infrared imaging component in the transverse direction, and the second beam splitter is used to decompose the incident light beam into a short-wave infrared beam and a laser beam. The second beam splitter is used to transmit the short-wave infrared beam and reflect the laser beam; the first beam splitter and the second beam splitter are both placed at 45° to the horizontal plane.

[0012] Further, in the short-wave infrared imaging assembly, the short-wave infrared light beam passes through a short-wave infrared first reflector, a short-wave infrared first cemented lens, a short-wave infrared second cemented lens, a short-wave infrared first lens, a short-wave infrared second lens and a short-wave infrared second reflector in sequence; The short-wave infrared first glued lens comprises: a short-wave infrared first glued lens 1 and a short-wave infrared first glued lens 2; the short-wave infrared second glued lens comprises: a short-wave infrared second glued lens 1 and a short-wave infrared second glued lens 2.

[0013] Furthermore, in the medium-wave imaging optical path, the medium-wave infrared light beam reflected by the coaxial folding afocal objective lens is transmitted through the first beam splitter and then emitted through the medium-wave infrared imaging component to the medium-wave infrared detector target surface for imaging.

[0014] Further, in the medium-wave infrared imaging assembly, the medium-wave infrared light beam sequentially passes through a medium-wave infrared first lens, a medium-wave infrared second lens, a medium-wave infrared first reflector, a medium-wave infrared third lens, a medium-wave infrared second reflector, a medium-wave infrared fourth lens, a medium-wave infrared fifth lens, a medium-wave infrared sixth lens, a medium-wave infrared detector window, and a medium-wave infrared detector filter; The first medium-wave infrared lens, the fourth medium-wave infrared lens and the sixth medium-wave infrared lens are meniscus spherical lenses with positive optical power, the second medium-wave infrared lens and the fifth medium-wave infrared lens are meniscus spherical lenses with negative optical power, the first medium-wave infrared reflector and the second medium-wave infrared reflector are both plane reflectors placed at 45° to the horizontal plane, and the third medium-wave infrared lens is a meniscus aspherical lens with positive optical power.

[0015] Furthermore, the wavelength of the medium-wave infrared light beam is 3 to 5 microns; the wavelength of the short-wave infrared light beam is 0.9 to 1.7 microns; and the wavelength of the laser light beam is 0.9 to 1.7 microns.

[0016] The beneficial effects of the method of the present invention are: (1) The present invention adopts a coaxial catadioptric afocal objective lens with a rear optical path structure, successfully achieving the common aperture integration of laser, short-wave infrared and medium-wave infrared multi-bands. This design not only enables accurate observation and imaging of targets in day and night environments, but also realizes an integrated optical design of laser emission and reception, greatly improving the performance of the system of the present invention in target detection, positioning and aiming, and laser guidance.

[0017] (2) The coaxial catadioptric structure uses a clever combination of multi-spectral materials to effectively correct chromatic aberration in a wide spectrum. While ensuring the high performance of the system, it fully takes into account volume control, magnification optimization, processing feasibility, installation and adjustment process convenience, field of view range, and rationality of structural layout. This enables the system to have good maneuverability and a high degree of integration, which in turn gives the system a powerful ability to detect multi-platform coordinated targets and conduct multi-task coordinated operations, providing a more efficient and flexible solution for applications in complex environments. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 It is a schematic diagram of the structure of the system of the present invention; Figure 2 It is a schematic diagram of the structure of the coaxial folding afocal objective lens of the present invention; Figure 3 This is a schematic diagram of the structure of the medium-wave infrared imaging component of the present invention; Figure 4 This is a schematic diagram of the structure of the collimating and beam expanding assembly of the present invention; Figure 5 It is a schematic diagram of the structure of the short-wave infrared imaging component of the present invention.

[0019] L1-primary mirror, L2-secondary mirror, L3-multi-band collimating lens assembly, L31-multi-band collimating first lens, L32-multi-band collimating second lens, L33-multi-band collimating third lens, L34-multi-band collimating fourth lens, L4-first reflector, L5-first spectroscope, L6-medium-wave infrared imaging assembly, L61-medium-wave infrared first lens, L62-medium-wave infrared second lens, L63-medium-wave infrared first reflector, L64-medium-wave infrared third lens, L65-medium-wave infrared second reflector, L66-medium-wave infrared fourth lens, L67-medium-wave infrared fifth lens, L68-medium-wave infrared sixth lens, L69-medium-wave infrared detector window, L610-medium-wave infrared detector filter, L7-second spectroscope, L8-collimating beam expander assembly, L81-laser collimating beam expander first lens, L82 -Laser collimation and beam expansion second lens, L83-Laser collimation and beam expansion third lens, L84-Laser collimation and beam expansion fourth lens, L85-Laser collimation and beam expansion fifth lens, L86-Laser collimation and beam expansion sixth lens, L87-Laser collimation and beam expansion seventh lens, L9-short-wave infrared imaging component, L91-short-wave infrared first reflector, L92-short-wave infrared first glued lens, L93-short-wave infrared second glued lens, L94-short-wave infrared first lens, L95-short-wave infrared second lens, L96-short-wave infrared second reflector, L921-short-wave infrared first glued lens one, L922-short-wave infrared first glued lens two, L931-short-wave infrared second glued lens one, L932-short-wave infrared second glued lens two, S1-medium-wave infrared detector target surface, S2-laser light source, S3-short-wave infrared detector target surface. DETAILED DESCRIPTION

[0020] The technical solution of the present invention will be described clearly and completely below in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the protection scope of the present invention.

[0021] This embodiment provides a compact coaxial foldback three-band multifunctional common aperture optical system, such as Figure 1 As shown, the device comprises: a coaxial folding afocal objective lens, a laser emission optical path, a short-wave imaging optical path and a medium-wave imaging optical path; The laser emission optical path emits a laser beam through a coaxial reentrant afocal objective lens to a target, the target reflects the laser beam and a short-wave infrared beam to the coaxial reentrant afocal objective lens, and at the same time the target radiates a medium-wave infrared beam to the coaxial reentrant afocal objective lens, the coaxial reentrant afocal objective lens reflects the laser beam and the short-wave infrared beam to the short-wave imaging optical path for imaging, and the coaxial reentrant afocal objective lens reflects the medium-wave infrared beam to the medium-wave imaging optical path for imaging; like Figure 1 and 2 As shown, the coaxial folding afocal objective lens comprises: a primary mirror L1, a secondary mirror L2, a multi-band collimating lens assembly L3 and a first reflecting mirror L4; The coaxial reentrant afocal objective lens includes a coaxial output optical path and a coaxial incident optical path; in the coaxial output optical path, the laser light beam emitted by the laser emission optical path passes through the first reflector L4, the multi-band collimating lens assembly L3, the secondary mirror L2 and the primary mirror L1 in sequence before being emitted to the target; in the coaxial incident optical path, the laser light beam, the short-wave infrared light beam and the medium-wave infrared light beam received by the primary mirror L1 pass through the primary mirror L1, the secondary mirror L2, the multi-band collimating lens assembly L3 and the first reflector L4 in sequence before being emitted to the first beam splitter L5. In the multi-band collimating lens assembly L3, the incident light beam passes through the multi-band collimating first lens L31, the multi-band collimating second lens L32, the multi-band collimating third lens L33 and the multi-band collimating fourth lens L34 in sequence; the materials of each lens in the multi-band collimating lens assembly L3 include multi-spectral zinc sulfide, calcium fluoride and spinel, and the combination of several materials enables it to have good achromatic ability in a wide band range.

[0022] The primary mirror L1 has a hole in the center, and its reflecting surface is a concave aspheric surface; the reflecting surface of the secondary mirror L2 is a convex aspheric surface; the multi-band collimating lens assembly L3 has a positive optical focal length, and is arranged between the secondary mirror L2 and the first reflecting mirror L4; the multi-band collimating lens assembly L3 is arranged on the horizontal line where the hole in the center of the primary mirror L1 is located; the first reflecting mirror L4 is arranged on the transmitted light path of the multi-band collimating lens assembly L3, and the reflecting surface of the first reflecting mirror L4 is a plane, and is placed at 45° to the vertical plane; in this embodiment, the material of the first reflecting mirror L4 is H-K9L produced by the domestic Chengdu Guangming Company, which has the characteristics of low price and stable production frequency; the reflecting surface of the secondary mirror L2 is a convex aspheric surface.

[0023] The materials of the primary mirror L1 and the secondary mirror L2 are microcrystals, and such a configuration enables the primary mirror L1 and the secondary mirror L2 to have the advantages of high and low temperature resistance and a small thermal expansion coefficient. The object focus of the multi-band collimating lens assembly L3 coincides with the image focus of the coaxial catadioptric structure composed of the primary mirror L1 and the secondary mirror L2, thereby forming a perfect imaging afocal system; the primary mirror L1 and the secondary mirror L2 adopt a coaxial catadioptric structure, and such a configuration can effectively solve the problem of long focal length and large aperture, and realize the integration of medium-wave infrared, short-wave infrared, and laser multi-band optical systems. Compared with the split-aperture optical path design, the entire system structure is compact, thereby realizing the miniaturization and lightweight of the optical system.

[0024] like Figure 1 As shown, the laser emission optical path includes: a laser light source S2, a collimating beam expansion component L8, a second beam splitter L7 and a first beam splitter L5.

[0025] The collimating and beam expanding component L8 and the laser light source S2 are arranged on the reflection light path of the second beam splitter L7; the laser light source S2 is a fiber optic light source for emitting a laser beam; the collimating and beam expanding component L8 is used to compress the divergence angle of the laser beam emitted by the laser light source S2.

[0026] The laser light beam emitted by the laser light source S2 in the laser emission optical path passes through the collimating beam expansion component L8, the second beam splitter L7 and the first beam splitter L5 in sequence, and then emerges to the coaxial folding afocal objective lens.

[0027] The materials of the first beam splitter L5 and the second beam splitter L7 are both single crystal silicon, and have good beam splitting capabilities.

[0028] like Figure 4 As shown, in the collimating beam expansion assembly L8, the laser beam passes through the first laser collimating beam expansion lens L81, the second laser collimating beam expansion lens L82, the third laser collimating beam expansion lens L83, the fourth laser collimating beam expansion lens L84, the fifth laser collimating beam expansion lens L85, the sixth laser collimating beam expansion lens L86 and the seventh laser collimating beam expansion lens L87 in sequence, and then is emitted to the second beam splitter L7; The first laser collimation and beam expansion lens L81, the fourth laser collimation and beam expansion lens L84, the sixth laser collimation and beam expansion lens L86 and the seventh laser collimation and beam expansion lens L87 are meniscus spherical lenses with positive optical focal length; the second laser collimation and beam expansion lens L82 and the fifth laser collimation and beam expansion lens L85 are biconcave spherical lenses with negative optical focal length; the third laser collimation and beam expansion lens L83 is a biconvex spherical lens with positive optical focal length.

[0029] like Figure 1 As shown, the short-wave imaging optical path includes: a first beam splitter L5, a second beam splitter L7, a short-wave infrared imaging component L9 and a short-wave infrared detector target surface S3; The short-wave infrared imaging component L9 is arranged on the transmission light path of the second beam splitter L7; the short-wave infrared imaging component L9 is used for imaging the short-wave infrared light beam on the target surface S3 of the short-wave infrared detector.

[0030] In the short-wave imaging optical path, the laser beam and the short-wave infrared beam reflected by the coaxial folding afocal objective are reflected by the first beam splitter L5, and then separated into a laser beam and a short-wave infrared beam by the second beam splitter L7. The short-wave infrared beam is then emitted to the short-wave infrared detector target surface S3 for imaging through the short-wave infrared imaging component L9; the laser beam is emitted into the laser light source S2; The first beam splitter L5 is arranged between the coaxial folding afocal objective lens and the medium-wave infrared imaging component L6 in the longitudinal direction, and is used to decompose the incident light beam into a medium-wave infrared beam, a short-wave infrared beam and a laser beam. The first beam splitter L5 is used to transmit the medium-wave infrared beam and reflect the short-wave infrared beam and the laser beam; the second beam splitter L7 is arranged between the first beam splitter L5 and the short-wave infrared imaging component L9 in the transverse direction, and the second beam splitter L7 is used to decompose the incident light beam into a short-wave infrared beam and a laser beam. The second beam splitter L7 is used to transmit the short-wave infrared beam and reflect the laser beam; the first beam splitter L5 and the second beam splitter L7 are both placed at 45° to the horizontal plane.

[0031] like Figure 5 As shown, in the short-wave infrared imaging component L9, the short-wave infrared light beam passes through the short-wave infrared first reflector L91, the short-wave infrared first cemented lens L92, the short-wave infrared second cemented lens L93, the short-wave infrared first lens L94, the short-wave infrared second lens L95 and the short-wave infrared second reflector L96 in sequence.

[0032] The shortwave infrared imaging component L9 independently improves the imaging.

[0033] The short-wave infrared first cemented lens L92 includes: a short-wave infrared first cemented lens 1 L921 and a short-wave infrared first cemented lens 2 L922; the short-wave infrared second cemented lens L93 includes: a short-wave infrared second cemented lens 1 L931 and a short-wave infrared second cemented lens 2 L932.

[0034] like Figure 1 As shown, the medium-wave imaging optical path includes: a first beam splitter L5, a medium-wave infrared imaging component L6 and a medium-wave infrared detector target surface S1.

[0035] In the medium-wave imaging optical path, the medium-wave infrared light beam reflected by the coaxial folding afocal objective lens is transmitted through the first beam splitter L5, and then emitted through the medium-wave infrared imaging component L6 to the medium-wave infrared detector target surface S1 for imaging.

[0036] like Figure 3As shown, in the medium-wave infrared imaging assembly L6, the medium-wave infrared light beam passes through the medium-wave infrared first lens L61, the medium-wave infrared second lens L62, the medium-wave infrared first reflector L63, the medium-wave infrared third lens L64, the medium-wave infrared second reflector L65, the medium-wave infrared fourth lens L66, the medium-wave infrared fifth lens L67, the medium-wave infrared sixth lens L68, the medium-wave infrared detector window L69 and the medium-wave infrared detector filter L610 in sequence.

[0037] The medium-wave infrared imaging component L6 independently improves imaging. The medium-wave infrared imaging component L6 adopts a secondary imaging structure. The imaging quality is close to the diffraction limit and achieves 100% cold stop matching.

[0038] The medium-wave infrared imaging component L6 and the short-wave infrared imaging component L9 independently improve the imaging design, making it easy to realize the integrated design and simultaneous imaging of short-wave and medium-wave infrared.

[0039] The medium-wave infrared first lens L61, the medium-wave infrared fourth lens L66 and the medium-wave infrared sixth lens L68 are meniscus spherical lenses with positive optical focal length, the medium-wave infrared second lens L62 and the medium-wave infrared fifth lens L67 are meniscus spherical lenses with negative optical focal length, the medium-wave infrared first reflector L63 and the medium-wave infrared second reflector L65 are both plane reflectors placed at 45° to the horizontal plane, and the medium-wave infrared third lens L64 is a meniscus aspherical lens with positive optical focal length.

[0040] The material of the medium-wave infrared first reflector L63 and the medium-wave infrared second reflector L65 is domestically produced H-K9L glass.

[0041] The collimating beam expansion component L8 and the short-wave infrared imaging component L9 both use domestic glass spherical lenses. This arrangement not only ensures the high yield advantage of processing and assembly, further reducing costs, but also ensures the high reliability of the product.

[0042] The placement of the first reflector L4, the first beam splitter L5, the second beam splitter L7, the first medium-wave infrared reflector L63 and the second medium-wave infrared reflector L65 can not only realize the deflection of light by changing the transmission angle of light, but also reduce the spatial volume of the system. The wavelength of the medium-wave infrared light beam is 3 to 5 microns. With such an arrangement, the present invention can realize uninterrupted imaging day and night and is not easily detected by enemy reconnaissance.

[0043] The wavelength of the short-wave infrared light beam is 0.9-1.7 microns; the wavelength of the laser light beam is 0.9-1.7 microns. With such an arrangement, the present invention enables the short-wave infrared imaging optical path to realize target detection and imaging while also realizing observation of the laser spot.

Claims

1. A compact coaxial return type three-band multifunctional common aperture optical system, characterized in that: The system comprises: a coaxial folding afocal objective lens, a laser emission optical path, a short-wave imaging optical path and a medium-wave imaging optical path; The laser emission optical path emits a laser beam through a coaxial reentrant afocal objective lens to a target, the target reflects the laser beam and a short-wave infrared beam to the coaxial reentrant afocal objective lens, and at the same time the target radiates a medium-wave infrared beam to the coaxial reentrant afocal objective lens, the coaxial reentrant afocal objective lens reflects the laser beam and the short-wave infrared beam to the short-wave imaging optical path for imaging, and the coaxial reentrant afocal objective lens reflects the medium-wave infrared beam to the medium-wave imaging optical path for imaging; The coaxial folding afocal objective lens comprises: a primary mirror (L1), a secondary mirror (L2), a multi-band collimating lens assembly (L3) and a first reflecting mirror (L4); The laser emission optical path includes: a laser light source (S2), a collimating beam expansion component (L8), a second beam splitter (L7) and a first beam splitter (L5); The short-wave imaging optical path includes: a first beam splitter (L5), a second beam splitter (L7), a short-wave infrared imaging component (L9) and a short-wave infrared detector target surface (S3); The medium-wave imaging optical path comprises: a first beam splitter (L5), a medium-wave infrared imaging component (L6) and a medium-wave infrared detector target surface (S1).

2. A compact coaxial return type three-band multifunctional common aperture optical system according to claim 1, characterized in that: The coaxial folding afocal objective lens comprises a coaxial output optical path and a coaxial incident optical path; in the coaxial output optical path, a laser beam emitted from the laser emission optical path passes through a first reflector (L4), a multi-band collimating lens assembly (L3), a secondary mirror (L2) and a primary mirror (L1) in sequence before being emitted to a target; in the coaxial incident optical path, a laser beam, a short-wave infrared beam and a medium-wave infrared beam received by the primary mirror (L1) pass through the primary mirror (L1), the secondary mirror (L2), the multi-band collimating lens assembly (L3) and the first reflector (L4) in sequence before being emitted to a first beam splitter (L5); the image-side focal points of the primary mirror (L1) and the secondary mirror (L2) coincide with the object-side focal point of the multi-band collimating lens assembly (L3).

3. A compact coaxial return type three-band multifunctional common aperture optical system according to claim 2, characterized in that: In the multi-band collimating lens assembly (L3), an incident light beam passes through a multi-band collimating first lens (L31), a multi-band collimating second lens (L32), a multi-band collimating third lens (L33) and a multi-band collimating fourth lens (L34) in sequence; the material of each lens in the multi-band collimating lens assembly (L3) includes multi-spectral zinc sulfide, calcium fluoride and spinel; The primary mirror (L1) has a hole in the center, and its reflecting surface is a concave aspheric surface; the reflecting surface of the secondary mirror (L2) is a convex aspheric surface; the multi-band collimating lens assembly (L3) has a positive optical focal length and is arranged between the secondary mirror (L2) and the first reflecting mirror (L4); the multi-band collimating lens assembly (L3) is arranged on a horizontal line where the hole in the center of the primary mirror (L1) is located; and the first reflecting mirror (L4) is placed at 45 degrees to the vertical plane.

4. The compact coaxial return type three-band multifunctional common aperture optical system according to claim 2, characterized in that: A laser light beam emitted by a laser light source (S2) in a laser emission optical path passes through a collimating beam expansion component (L8), a second beam splitter (L7) and a first beam splitter (L5) in sequence before being emitted to a coaxial folding afocal objective lens.

5. The compact coaxial return type three-band multifunctional common aperture optical system according to claim 4, characterized in that: In the collimating and beam expanding assembly (L8), the laser beam passes through a laser collimating and beam expanding first lens (L81), a laser collimating and beam expanding second lens (L82), a laser collimating and beam expanding third lens (L83), a laser collimating and beam expanding fourth lens (L84), a laser collimating and beam expanding fifth lens (L85), a laser collimating and beam expanding sixth lens (L86) and a laser collimating and beam expanding seventh lens (L87) in sequence, and then is emitted to a second beam splitter (L7); The first laser collimation and beam expansion lens (L81), the fourth laser collimation and beam expansion lens (L84), the sixth laser collimation and beam expansion lens (L86) and the seventh laser collimation and beam expansion lens (L87) are meniscus spherical lenses with positive optical focal length; the second laser collimation and beam expansion lens (L82) and the fifth laser collimation and beam expansion lens (L85) are biconcave spherical lenses with negative optical focal length; and the third laser collimation and beam expansion lens (L83) is a biconvex spherical lens with positive optical focal length.

6. The compact coaxial return type three-band multifunctional common aperture optical system according to claim 2, characterized in that: In the short-wave imaging optical path, the laser beam and the short-wave infrared beam reflected by the coaxial folding afocal objective lens are reflected by a first beam splitter (L5), and then separated into a laser beam and a short-wave infrared beam by a second beam splitter (L7). The short-wave infrared beam is then emitted to a short-wave infrared detector target surface (S3) for imaging via a short-wave infrared imaging component (L9); the laser beam is emitted into a laser light source (S2); The first beam splitter (L5) is arranged between the coaxial folding afocal objective lens and the medium-wave infrared imaging component (L6) in the longitudinal direction, and is used to decompose the incident light beam into a medium-wave infrared beam, a short-wave infrared beam and a laser beam. The first beam splitter (L5) is used to transmit the medium-wave infrared beam and reflect the short-wave infrared beam and the laser beam. The second beam splitter (L7) is arranged between the first beam splitter (L5) and the short-wave infrared imaging component (L9) in the transverse direction. The second beam splitter (L7) is used to decompose the incident light beam into a short-wave infrared beam and a laser beam. The second beam splitter (L7) is used to transmit the short-wave infrared beam and reflect the laser beam. The first beam splitter (L5) and the second beam splitter (L7) are both placed at 45 degrees to the horizontal plane.

7. The compact coaxial return type three-band multifunctional common aperture optical system according to claim 6, characterized in that: In the short-wave infrared imaging component (L9), the short-wave infrared light beam passes through a short-wave infrared first reflector (L91), a short-wave infrared first cemented lens (L92), a short-wave infrared second cemented lens (L93), a short-wave infrared first lens (L94), a short-wave infrared second lens (L95) and a short-wave infrared second reflector (L96) in sequence; The short-wave infrared first glued lens (L92) comprises: a short-wave infrared first glued lens 1 (L921) and a short-wave infrared first glued lens 2 (L922); the short-wave infrared second glued lens (L93) comprises: a short-wave infrared second glued lens 1 (L931) and a short-wave infrared second glued lens 2 (L932).

8. The compact coaxial return type three-band multifunctional common aperture optical system according to claim 2, characterized in that: In the medium-wave imaging optical path, the medium-wave infrared light beam reflected by the coaxial folding afocal objective lens is transmitted through the first beam splitter (L5), and then emitted through the medium-wave infrared imaging component (L6) to the medium-wave infrared detector target surface (S1) for imaging.

9. The compact coaxial return type three-band multifunctional common aperture optical system according to claim 8, characterized in that: In the medium-wave infrared imaging assembly (L6), the medium-wave infrared light beam passes through a medium-wave infrared first lens (L61), a medium-wave infrared second lens (L62), a medium-wave infrared first reflector (L63), a medium-wave infrared third lens (L64), a medium-wave infrared second reflector (L65), a medium-wave infrared fourth lens (L66), a medium-wave infrared fifth lens (L67), a medium-wave infrared sixth lens (L68), a medium-wave infrared detector window (L69), and a medium-wave infrared detector filter (L610) in sequence; The medium-wave infrared first lens (L61), the medium-wave infrared fourth lens (L66) and the medium-wave infrared sixth lens (L68) are meniscus spherical lenses with positive optical focal length, the medium-wave infrared second lens (L62) and the medium-wave infrared fifth lens (L67) are meniscus spherical lenses with negative optical focal length, the medium-wave infrared first reflector (L63) and the medium-wave infrared second reflector (L65) are both plane reflectors placed at 45 degrees to the horizontal plane, and the medium-wave infrared third lens (L64) is a meniscus aspherical lens with positive optical focal length.

10. The compact coaxial return type three-band multifunctional common aperture optical system according to claim 1, characterized in that: The wavelength of the medium-wave infrared light beam is 3-5 microns; the wavelength of the short-wave infrared light beam is 0.9-1.7 microns; and the wavelength of the laser light beam is 0.9-1.7 microns.

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