A dual-band co-aperture focal-contraction optical system

Abstract

This invention relates to the field of optical system technology, and more particularly to a dual-band, co-aperture, focusless beam-shrinking optical system, comprising: an aperture stop, a first lens, a second lens, a third lens, a fourth lens, and a fifth lens arranged coaxially along the incident direction of light; the first, second, third, and fifth lenses are positive lenses, and the fourth lens is a negative lens; a parallel incident laser beam and an infrared beam are incident on the first lens through the aperture stop, converge to form a first converging beam which is then incident on the second lens, converge to form a second converging beam which is then incident on the third lens, converge to form a third converging beam which is then incident on the fourth lens, diverge to form a diverging beam which is then incident on the fifth lens, and finally converge to form a parallel outgoing beam. This technical solution allows the laser beam and the infrared beam to share the same set of lenses and propagate along the same optical path, effectively solving the problems of complex structure, large size, and poor optical axis consistency caused by the need for independent design in traditional dual-band systems.

Description

Technical Field

[0001] This invention relates to the field of optical system technology, and in particular to a dual-band common aperture afocal-free beam-shrinking optical system. Background Technology

[0002] With the continuous development of optoelectronic technology, laser and infrared technologies have been widely used in various fields such as military, aerospace, and industrial inspection. Laser beams have the characteristics of high energy and high precision, enabling precise measurement, communication, and processing over long distances; while infrared light has high sensitivity to thermal radiation, making it suitable for tasks such as target detection, imaging, and identification.

[0003] In existing technologies, combining laser and infrared technologies to form a laser-infrared dual-band system can fully leverage the advantages of both, achieving more comprehensive and efficient optoelectronic functions. However, due to the significant difference in wavelength between laser and long-wave infrared, separate optical systems are usually required. This not only increases the complexity and size of the system but may also lead to problems such as difficulties in optical path alignment and poor consistency of the dual-band optical axes.

[0004] Therefore, those skilled in the art urgently need to develop a new technical solution to address the above problems. Summary of the Invention

[0005] This invention provides a dual-band, co-aperture, focusless beam-shrinking optical system that enables laser and infrared beams to share the same lens group and propagate along the same optical path. This effectively solves the problems of complex structure, large size, and poor optical axis consistency caused by the need for independent design in traditional dual-band systems. The system includes: An aperture stop, a first lens, a second lens, a third lens, a fourth lens, and a fifth lens are arranged coaxially along the direction of light incidence. The first lens, the second lens, the third lens, and the fifth lens are positive power lenses, and the fourth lens is a negative power lens; Parallel incident laser beams and infrared beams are incident on the first lens through the aperture, and converged by the first lens to form a first converging beam; the first converging beam is incident on the second lens, and converged by the second lens to form a second converging beam; the second converging beam is incident on the third lens, and converged by the third lens to form a third converging beam; the third converging beam is incident on the fourth lens, and diverged by the fourth lens to form a diverging beam; the diverging beam is incident on the fifth lens, and converged by the fifth lens to form a parallel outgoing beam, the aperture of the parallel outgoing beam being smaller than the aperture of the parallel incident laser beam and the aperture of the parallel incident infrared beam, respectively.

[0006] This invention provides a dual-band, common-aperture, focusless beam-shrinking optical system. By sequentially arranging an aperture stop, a first lens, a second lens, a third lens, a fourth lens, and a fifth lens along the optical path, the laser beam and the infrared beam share the same set of lenses and propagate along the same optical path. This effectively solves the problems of complex structure, large size, and poor optical axis consistency caused by the need for independent design in traditional dual-band systems. Simultaneously, this system achieves focusless collimation characteristics, where parallel light input converges, diverges, and then outputs parallel light, and ensures that the output beam aperture is smaller than the input beam aperture, thus completing the beam-shrinking function. The system of this invention has a compact structure and good stability, making it suitable for integration into high-precision photoelectric tracking platforms. It can effectively support the integrated functions of laser ranging, target indication, and infrared imaging, significantly improving the environmental adaptability and response accuracy of multimodal systems. Attached Figure Description

[0007] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0008] Figure 1 This is a schematic diagram of the structure of a dual-band co-aperture focal-contraction optical system according to an embodiment of the present invention; Figure 2 This is a transfer function curve of an optical system in the laser band provided by the present invention; Figure 3 This is a transfer function curve of an optical system provided by the present invention in the long-wave infrared band; Figure 4 This is a dot plot of an optical system in the laser band provided by the present invention; Figure 5 This is a dot plot of an optical system provided by the present invention in the long-wave infrared band; Figure 6 This invention provides a field curvature diagram of an optical system in dual-band conditions. Figure 7 This is a distortion diagram of an optical system under dual-band conditions provided by the present invention. Detailed Implementation

[0009] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are some embodiments of the present invention, but not all embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0010] Please refer to Figure 1 This invention provides a dual-band co-aperture focal-contraction optical system, comprising: An aperture stop 1, a first lens 2, a second lens 3, a third lens 4, a fourth lens 5, and a fifth lens 6 are arranged coaxially along the direction of light incidence. The first lens 2, the second lens 3, the third lens 4 and the fifth lens 6 are positive power lenses, and the fourth lens 5 is a negative power lens. Parallel incident laser beams and infrared beams are incident through aperture 1 onto first lens 2, where they converge to form a first converging beam. The first converging beam is then incident onto second lens 3, where it converges to form a second converging beam. The second converging beam is then incident onto third lens 4, where it converges to form a third converging beam. The third converging beam is then incident onto fourth lens 5, where it diverges to form a diverging beam. Finally, the diverging beam is incident onto fifth lens 6, where it converges to form a parallel exit beam. The aperture of the parallel exit beam is smaller than the aperture of both the parallel incident laser beam and the parallel incident infrared beam. Figure 4 and Figure 5 The diagram shown is a dot plot of the optical system under dual-band conditions, which reflects the good collimation effect of the system. This invention provides a focusless beam-shrinking optical system for coaxial, shared-path transmission of laser and long-wave infrared wavelengths. This system employs a common-aperture design, possessing large-aperture collimation capabilities, and provides a good focusless system for simultaneous laser and long-wave infrared imaging, effectively improving the energy utilization of both wavelengths. The optical lens includes an aperture stop 1, a first lens 2, a second lens 3, a third lens 4, a fourth lens 5, a fifth lens 6, and an image plane 7, arranged sequentially along the light incident direction. The lenses are made of aspherical materials, which can correct aberrations in both wavelengths, eliminate focal shift between the two wavelengths, and ensure focusless collimation across a wide spectral range. The system has a compact overall structure, making it suitable for integrated photoelectric detection equipment.

[0011] In one embodiment of the present invention, the first lens 2 is made of ZnS material, the third lens 4 is made of BaF2 material, and the second lens 3, the fourth lens 5 and the fifth lens 6 are made of IRG206 material.

[0012] In this embodiment, the third lens 4 is made of BaF2 material, which can eliminate chromatic aberration caused by wide wavelengths, and its transfer function curves are close to the diffraction limit in both laser and long-wave infrared bands. BaF2 material has excellent transmittance and low dispersion characteristics, enabling good optical matching between laser beams and infrared beams. The first lens 2 is made of ZnS material, and the second lens 3, fourth lens 5, and fifth lens 6 are made of IRG206 material. This optical system uses only three lens materials, greatly reducing the difficulty and cost of the manufacturing process. While ensuring dual-band afocal performance, it effectively controls the assembly and adjustment complexity of the system. In addition, the selection of the three materials takes into account both thermal stability and optical performance, enabling the system to maintain good optical path consistency in a wide temperature environment.

[0013] In one embodiment of the present invention, the thickness of the first lens 2 is 20mm-30mm, the thickness of the second lens 3 is 10mm-20mm, the thickness of the third lens 4 is 15mm-25mm, the thickness of the fourth lens 5 is 10mm-20mm, and the thickness of the fifth lens 6 is 10mm-20mm.

[0014] In this embodiment, the thickness of the first lens 2 is 20mm-30mm, preferably 25mm; the thickness of the second lens 3 is 10mm-20mm, preferably 15mm; the thickness of the third lens 4 is 15mm-25mm, preferably 20mm; the thickness of the fourth lens 5 is 10mm-20mm, preferably 15mm; and the thickness of the fifth lens 6 is 10mm-20mm, preferably 15.5mm.

[0015] A reasonable thickness distribution results in a more uniform optical power distribution among the lenses, effectively avoiding spherical aberration and coma introduced by a single lens bearing excessive convergence or divergence, thus reducing the difficulty of system aberration correction. Within the aforementioned thickness range, a good matching relationship is formed between the axial dimensions of each lens and the overall length of the system. This allows the optical system to maintain a large aperture (120mm) and a large relative aperture (F-number 2) while having a more compact overall structure, facilitating integration into miniaturized photoelectric detection platforms. This thickness range is compatible with the characteristics of the three materials in the system: ZnS, IRG206, and BaF2. It fully leverages the advantages of BaF2 material in wide-band achromaticity while ensuring the process feasibility of molding IRG206 chalcogenide glass, reducing processing costs and assembly complexity.

[0016] In one embodiment of the present invention, the distance between the aperture stop 1 and the front surface of the first lens 2 is 3mm-8mm, the distance between the rear surface of the first lens 2 and the front surface of the second lens 3 is 3mm-8mm, the distance between the rear surface of the second lens 3 and the front surface of the third lens 4 is 3mm-8mm, the distance between the rear surface of the third lens 4 and the front surface of the fourth lens 5 is 80mm-92mm, the distance between the rear surface of the fourth lens 5 and the front surface of the fifth lens 6 is 72mm-85mm, and the distance between the rear surface of the fifth lens 6 and the image plane 7 is 64mm-76mm.

[0017] In this embodiment, the distance between the front surface of the first lens 2 and the aperture stop 1 is 3mm-8mm, preferably 5mm; the distance between the rear surface of the first lens 2 and the front surface of the second lens 3 is 3mm-8mm, preferably 5mm; the distance between the rear surface of the second lens 3 and the front surface of the third lens 4 is 3mm-8mm, preferably 5mm; the distance between the rear surface of the third lens 4 and the front surface of the fourth lens 5 is 80mm-92mm, preferably 86mm; the distance between the rear surface of the fourth lens 5 and the front surface of the fifth lens 6 is 72mm-85mm, preferably 78.5mm; and the distance between the rear surface of the fifth lens 6 and the image plane 7 is 64mm-76mm, preferably 70mm.

[0018] By controlling the distance between the aperture stop 1 and the front surface of the first lens 2 to 3mm-8mm, setting the axial spacing between adjacent lenses, and setting the distance from the rear surface of the fifth lens 6 to the image plane 7 within the aforementioned preferred ranges, the aberration correction capability and focusless beam-shrinking performance of the optical system are significantly optimized. Specifically, the reasonable selection of the first three air gaps (3mm-8mm) creates an appropriate light transition area between the first three positive lenses, ensuring that the incident height of the beam on each lens surface is moderate, effectively suppressing the generation of higher-order spherical aberration and coma, while avoiding mechanical interference caused by excessively small gaps or an increase in the total system length caused by excessively large gaps. Setting the gap between the third lens 4 and the fourth lens 5 to 80mm-92mm and the gap between the fourth lens 5 and the fifth lens 6 to 72mm-85mm provides sufficient propagation space for the diverging beam of the negative power fourth lens 5, allowing the beam to reach a suitable divergence angle before entering the fifth lens 6, thereby ensuring that the fifth lens 6 can efficiently refocus the beam into parallel light output. The setting of 64mm-76mm for the distance from the rear surface of the fifth lens 6 to the image plane 7 provides a design margin for precise position control of the real exit pupil, facilitating optical path coupling between the system and the fast-reflecting mirror.

[0019] In one embodiment of the present invention, at least one surface of the first lens 2, the third lens 4, the fourth lens 5 and the fifth lens 6 is an aspherical structure.

[0020] In this embodiment, by precisely controlling the refractive index and Abbe number of each lens, combined with an aspherical structure design, off-axis aberrations are effectively corrected, improving the overall imaging quality of the system. This afocal system maintains beam collimation even in a large field of view, meeting the high-precision coaxial requirements of laser pointing and infrared imaging, and providing a stable optical path foundation for subsequent image shift compensation by the fast-reflecting mirror. At least one optical surface of the first lens 2, the third lens 4, the fourth lens 5, and the fifth lens 6 is set aspherical. Specifically, the rear surface of the first lens 2, the rear surface of the third lens 4, the front surface of the fourth lens 5, and the rear surface of the fifth lens 6 are all aspherical, while the two surfaces of the second lens 3 maintain a spherical design. This aspherical distribution scheme fully leverages the advantages of aspherical surfaces in correcting off-axis aberrations, effectively suppressing coma, astigmatism, and field curvature introduced by the large field of view (1.8°×1.8° for infrared, 0.35°×0.35° for laser), enabling the system to maintain good beam collimation across the entire field of view. By concentrating aspherical surfaces on surfaces where light refraction is significant (such as the rear surface of the third lens 4 and the front surface of the fourth lens 5), optimal aberration balance can be achieved with the fewest aspherical surfaces, avoiding the increased processing costs and inspection difficulties caused by excessive use of aspherical surfaces. Furthermore, the use of BaF2 material for the third lens 4 and its rear surface as an aspherical surface is one of the core features of this embodiment. BaF2 material has excellent transmittance and low dispersion characteristics in both laser and long-wave infrared bands. Fabricating it as an aspherical surface can simultaneously correct dual-band chromatic aberration and spherical aberration, solving the technical challenge of traditional spherical systems in simultaneously achieving confocal surface imaging in two widely separated bands: 1.064μm and 7.7-10.3μm.

[0021] In one embodiment of the present invention, the aspherical sagitta of the first lens 2, the third lens 4, the fourth lens 5, and the fifth lens 6 is expressed by the following formula: Z For aspherical sag, c It is the reciprocal of the radius of curvature at the vertex of the aspherical surface. r Radial coordinates, k The conic coefficient, a 2, a 4 and a 6 represents the aspheric coefficient.

[0022] In this embodiment, the surface shape of each aspherical lens is accurately described and optimized using the aforementioned even-order aspherical formula. This aspherical expression provides ample freedom for optical design. By rationally setting the radius of curvature, conic coefficient, and aspherical coefficient of each aspherical surface, the local curvature of the lens surface can be finely controlled. This effectively corrects various aberrations, such as spherical aberration, coma, astigmatism, and field curvature, introduced by large relative apertures (F-number 2) and wide viewing angles, ensuring good beam collimation across the entire field of view. This aspherical formula is particularly suitable for the patented dual-band co-aperture system of laser (1064nm) and long-wave infrared (7.7-10.3μm). Since the wavelengths of the two bands differ by approximately 8.5 times, traditional spherical systems struggle to simultaneously meet the aberration correction requirements of both bands. This embodiment optimizes the higher-order coefficients of each aspherical surface, fully utilizing the low dispersion characteristics of BaF2 material to achieve simultaneous correction of dual-band chromatic aberration. This ensures that the laser and infrared beams are collimated and output from the same image plane (position 7). The formula only uses the sixth power of r, controlling the complexity of the aspherical surface while guaranteeing sufficient aberration correction capability. This reduces the difficulty and cost of aspherical surface processing and inspection, resulting in good manufacturability.

[0023] In one embodiment of the present invention, the rear surface of the first lens 2 is an aspherical structure with an aspherical coefficient of . a 2 = 2.9 × 10 -7 , a 4 = -4.036 × 10 -11 , a 6 = 3.824 × 10 -15 ; The rear surface of the third lens 4 is an aspherical structure with an aspherical coefficient of . a 2 = -6.5 × 10 -7 , a 4 = 5.668 × 10 -10 , a 6 = -1.867 × 10 -13 ; The front surface of the fourth lens 5 is an aspherical structure with an aspherical coefficient of . a 2 = 1.975 × 10 -7 , a 4 = -3.787 × 10 -9 , a 6 = 5.3875 × 10 -12 ; The rear surface of the fifth lens 6 is an aspherical structure with an aspherical coefficient of . a 2 = -1.293 × 10 -7 , a 4 = 7.024 × 10-11 , a 6 = -1.394 × 10 -14 .

[0024] In this embodiment, by assigning specific aspherical coefficients to the rear surfaces of the first lens 2, the third lens 4, the fourth lens 5, and the fifth lens 6, respectively, a precise balance of overall system aberrations and synergistic optimization of dual-band performance are achieved. Specifically, the rear surface of the first lens 2 effectively corrects the primary spherical aberration and positional chromatic aberration generated after the light is converged by the first lens 2, providing good incident beam quality for subsequent lenses. The rear surface of the third lens 4, in conjunction with the low dispersion characteristics of the BaF2 material itself, is the core component of this patent for achieving dual-band achromatic aberration. It can significantly compensate for the focus shift caused by the wavelength difference between laser and long-wave infrared, ensuring that the beams of the two bands maintain confocal transmission in the subsequent optical path. The front surface of the fourth lens 5, located on the incident side of the negative power lens, effectively suppresses coma and astigmatism introduced by beam divergence, ensuring the symmetry and uniformity of the beam before entering the fifth lens 6. The rear surface of the fifth lens 6 is the key surface for the final collimation of the beam. Its aspherical coefficient accurately corrects the advanced aberrations left over from the previous group, ensuring that the output beam has good parallelism and wavefront quality.

[0025] In one embodiment of the present invention, the radius of curvature of the front surface of the first lens 2 is 92.535 mm, and the radius of curvature of the rear surface of the first lens 2 is 872.339 mm. The radius of curvature of the front surface of the second lens 3 is 116.329 mm, and the radius of curvature of the rear surface of the second lens 3 is 58.017 mm. The radius of curvature of the front surface of the third lens 4 is 56.474 mm, and the radius of curvature of the rear surface of the third lens 4 is 41.685 mm. The radius of curvature of the front surface of the fourth lens 5 is 42.222 mm, and the radius of curvature of the rear surface of the fourth lens 5 is 46.558 mm. The radius of curvature of the front surface of the fifth lens 6 is -879.784 mm, and the radius of curvature of the rear surface of the fifth lens 6 is -107.616 mm.

[0026] In this embodiment, as Figure 2 and Figure 3As shown, the transfer function curves of this system are close to the diffraction limit in both the laser and long-wave infrared bands. The first lens 2 features a curved front surface and an extremely flat rear surface, ensuring sufficient positive optical power to converge the incident beam while effectively controlling spherical and chromatic aberration generated within the first lens 2, laying a solid foundation for subsequent aberration correction. The second lens 3 has a front surface curvature radius of 116.329 mm and a rear surface curvature radius of 58.017 mm, further converging the light within this lens while achieving good optical power matching with the air gaps before and after, avoiding higher-order aberrations introduced by excessively steep light deflection. The third lens 4, as the core achromatic element, has a front surface curvature radius of 56.474 mm and a rear surface curvature radius of 41.685 mm. Combined with the low dispersion characteristics of the BaF2 material, it makes the focal positions of the laser and long-wave infrared tend to coincide, effectively eliminating axial chromatic aberration between the two bands. The fourth lens 5 has a front surface curvature radius of 42.222 mm and a rear surface curvature radius of 46.558 mm. As the only negative power lens in the system, it can effectively diverge light from the front group, providing a suitable incident height for the rear group, while correcting field curvature and distortion. The fifth lens 6 has a front surface curvature radius of -879.784 mm (close to a plane) and a rear surface curvature radius of -107.616 mm. It can refocus the diverging beam into a collimated beam output and precisely control the aperture and exit pupil position of the output beam.

[0027] In one embodiment of the present invention, the wavelength of the laser beam is 1064 nm, and the wavelength range of the infrared beam is 7.7 μm-10.3 μm.

[0028] In this embodiment, the laser beam has a wavelength of 1064nm, which has advantages such as high atmospheric transmittance, relatively good eye safety, and mature detectors, and is widely used in laser ranging, laser pointing, and lidar. The infrared beam has a wavelength range of 7.7μm-10.3μm, which is the peak region of thermal radiation from targets at room temperature, and is less affected by adverse weather conditions such as smoke and dust, enabling all-weather, long-distance target detection and thermal imaging. This patent uses optical design to combine these two wavelength bands, which are about 8.5 times apart, in the same afocal-free beam-shrinking system, realizing the fusion of active laser detection and passive infrared imaging. The system can emit a 1064nm laser for precise ranging and aiming, and can also receive infrared thermal radiation from 7.7μm-10.3μm for wide-range searching and target identification. The two functions complement each other and work synergistically, significantly improving the overall efficiency of the multimodal optoelectronic system. The two bands share the same optical path and the same aperture, avoiding the problems of large size, increased weight, and difficulty in ensuring optical axis consistency caused by the need for two independent optical modules in traditional dual-band systems. This makes the system structure more compact and lightweight, and easier to integrate into drones, vehicle platforms or portable devices.

[0029] In one embodiment of the present invention, the field of view of the parallel incident laser beam is 0.35° × 0.35°; The field of view of the parallel incident infrared beam is 1.8° × 1.8°.

[0030] In this embodiment, as Figure 6 and Figure 7 The diagram shows the field curvature and distortion of the optical system in dual-band conditions. The infrared field of view is relatively large (1.8° × 1.8°), which is beneficial for the system to receive the thermal radiation emitted by the target itself over a wide area, enabling rapid scanning and searching of a broad airspace or ground. Once a suspicious target is detected, the system can quickly align the optical axis with the target area. The laser field of view is relatively small (0.35° × 0.35°), only about one-fifth of the infrared field of view. This narrow field of view design allows for highly concentrated laser energy, significantly increasing the laser power density per unit area, thereby significantly enhancing the effective range and accuracy of laser ranging. It also reduces sidelobe interference, improving the accuracy of laser pointing and its anti-interference capability. Both fields of view share the same optical system and have aligned optical axes, achieving functional synergy between "wide field of view search" and "narrow field of view aiming." The infrared channel utilizes the large field of view to quickly detect targets, while the laser channel utilizes the small field of view for precise ranging and tracking of detected targets. The two modes can be seamlessly switched, avoiding the increased size and weight and optical axis alignment errors caused by the need for two independent optical paths for searching and aiming in traditional systems.

[0031] It should be noted that, in this invention, relational terms such as "first" and "second" are used merely to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus.

[0032] Finally, it should be noted that the above description is merely a preferred embodiment of the present invention and is only used to illustrate the technical solution of the present invention, and is not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention are included within the scope of protection of the present invention.

Claims

1. A dual-band, co-aperture, focusless beam-contraction optical system, characterized in that, include: An aperture stop, a first lens, a second lens, a third lens, a fourth lens, and a fifth lens are arranged coaxially along the direction of light incidence. The first lens, the second lens, the third lens, and the fifth lens are positive power lenses, and the fourth lens is a negative power lens; Parallel incident laser beams and infrared beams are incident on the first lens through the aperture, and converged by the first lens to form a first converging beam; the first converging beam is incident on the second lens, and converged by the second lens to form a second converging beam; the second converging beam is incident on the third lens, and converged by the third lens to form a third converging beam; the third converging beam is incident on the fourth lens, and diverged by the fourth lens to form a diverging beam; the diverging beam is incident on the fifth lens, and converged by the fifth lens to form a parallel outgoing beam, the aperture of the parallel outgoing beam being smaller than the aperture of the parallel incident laser beam and the aperture of the parallel incident infrared beam, respectively.

2. The system according to claim 1, characterized in that, The first lens is made of ZnS material, the third lens is made of BaF2 material, and the second, fourth and fifth lenses are made of IRG206 material.

3. The system according to claim 1, characterized in that, The thickness of the first lens ranges from 20mm to 30mm, the thickness of the second lens ranges from 10mm to 20mm, the thickness of the third lens ranges from 15mm to 25mm, the thickness of the fourth lens ranges from 10mm to 20mm, and the thickness of the fifth lens ranges from 10mm to 20mm.

4. The system according to claim 1, characterized in that, The distance between the aperture stop and the front surface of the first lens is 3mm-8mm, the distance between the rear surface of the first lens and the front surface of the second lens is 3mm-8mm, the distance between the rear surface of the second lens and the front surface of the third lens is 3mm-8mm, the distance between the rear surface of the third lens and the front surface of the fourth lens is 80mm-92mm, the distance between the rear surface of the fourth lens and the front surface of the fifth lens is 72mm-85mm, and the distance between the rear surface of the fifth lens and the image plane is 64mm-76mm.

5. The system according to claim 1, characterized in that, At least one surface of the first lens, the third lens, the fourth lens, and the fifth lens is an aspherical structure.

6. The system according to claim 5, characterized in that, The aspherical sagitta of the first lens, the third lens, the fourth lens, and the fifth lens is expressed by the following formula: Z For aspherical sag, c It is the reciprocal of the radius of curvature at the vertex of the aspherical surface. r Radial coordinates, k The conic coefficient, a 2, a 4 and a 6 represents the aspheric coefficient.

7. The system according to claim 6, characterized in that, The rear surface of the first lens is an aspherical structure with an aspherical coefficient of . a 2 = 2.9 × 10 -7 , a 4 = -4.036 × 10 -11 , a 6 = 3.824 × 10 -15 ; The rear surface of the third lens is an aspherical structure with an aspherical coefficient of . a 2 = -6.5 × 10 -7 , a 4 = 5.668 × 10 -10 , a 6 = -1.867 × 10 -13 ; The front surface of the fourth lens has an aspherical structure, and the aspherical coefficient is [value missing]. a 2 = 1.975 × 10 -7 , a 4 = -3.787 × 10 -9 , a 6 = 5.3875 × 10 -12 ; The rear surface of the fifth lens is an aspherical structure with an aspherical coefficient of . a 2 = -1.293 × 10 -7 , a 4 = 7.024 × 10 -11 , a 6 = -1.394 × 10 -14 .

8. The system according to claim 1, characterized in that, The radius of curvature of the front surface of the first lens is 92.535 mm, and the radius of curvature of the rear surface of the first lens is 872.339 mm. The radius of curvature of the front surface of the second lens is 116.329 mm, and the radius of curvature of the rear surface of the second lens is 58.017 mm. The radius of curvature of the front surface of the third lens is 56.474 mm, and the radius of curvature of the rear surface of the third lens is 41.685 mm. The radius of curvature of the front surface of the fourth lens is 42.222 mm, and the radius of curvature of the rear surface of the fourth lens is 46.558 mm. The radius of curvature of the front surface of the fifth lens is -879.784 mm, and the radius of curvature of the rear surface of the fifth lens is -107.616 mm.

9. The system according to claim 1, characterized in that, The laser beam has a wavelength of 1064 nm, and the infrared beam has a wavelength range of 7.7 μm-10.3 μm.

10. The system according to claim 1, characterized in that, The field of view of the parallel incident laser beam is 0.35° × 0.35°; The field of view of the parallel incident infrared beam is 1.8° × 1.8°.

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