Miniaturized three-mode compound detection optical system

Abstract

This invention belongs to the field of target detection technology, and particularly relates to a miniaturized three-mode composite detection optical system. Target light rays are transmitted through a radome and then incident on a primary mirror. The primary mirror reflects the target light rays onto a secondary mirror. A dichroic film is coated on the surface of the secondary mirror closest to the primary mirror, separating the target light rays into laser and infrared rays. The laser rays sequentially pass through the optical surface of the secondary mirror closest to the radome, a first lens, a second lens, and a filter to reach the photosensitive surface of a laser four-quadrant detector. The infrared rays sequentially pass through a first infrared lens, a second infrared lens, and a third infrared lens to reach an infrared detector. Millimeter-wave signals emitted by a millimeter-wave waveguide slotted array radar are radiated to the target sequentially through the primary mirror and the radome. The echo signals reflected by the target are transmitted through the radome and the primary mirror sequentially before reaching the millimeter-wave waveguide slotted array radar. This invention can reduce the system length and volume, and expand the rotation angle of the servo frame within a limited space.

Description

Technical Field

[0001] This invention belongs to the field of target detection technology, and in particular relates to a miniaturized three-mode composite detection optical system. Background Technology

[0002] In the field of photoelectric detection and precise identification technology, target detection scenarios are becoming increasingly complex, and environmental interference factors are increasing. Single-mode detection equipment can no longer meet the detection needs under multiple scenarios and conditions. With the development of target stealth technology and anti-interference technology, as well as the impact of harsh environments such as rain, fog, strong light, and complex backgrounds, higher requirements are placed on the comprehensive performance of detection systems. Multi-mode composite detection technology, with its synergistic advantages of multiple frequency bands and multiple principles, has become a core solution for improving detection accuracy, anti-interference capability, and environmental adaptability. Infrared, laser, and radar multi-mode composite detection systems have also become a key research and development direction in the industry.

[0003] Existing multimode composite detection systems are mainly divided into two types: common aperture and split aperture structures. Among them, the common aperture structure has become the mainstream design scheme due to its high space utilization and good optical axis consistency. The mainstream technical scheme mostly adopts the Cassegrain optical structure. After reflection by primary and secondary mirrors, the laser beam and infrared beam are separated by a beam-splitting prism, and the millimeter-wave radar antenna is arranged on the side of the secondary mirror or the rear of the primary mirror. This type of structure has obvious design limitations: to achieve the beam splitting requirement, the back cutoff of the system needs to be lengthened, resulting in an increase in the primary and secondary mirror blocking ratio and a significant decrease in the energy utilization of the infrared and laser beam paths; at the same time, the splitting of infrared and laser beams results in a longer optical path length behind the primary mirror, making the system's axial dimension larger and its volume bulkier. Within the limited installation space, the rotation angle range of the servo frame is limited, affecting the detection coverage of the detection system. If the aperture and focal length are compressed to adapt to the rotation angle, it will lead to a decrease in the long-distance detection and recognition capability of the detection system, making it impossible to meet the core requirements of miniaturization, large rotation angle, and high-performance detection. Summary of the Invention

[0004] In view of this, the present invention aims to provide a miniaturized three-mode composite detection optical system to solve the problems of the existing system having a long axial length, limited rotation angle range of the servo frame in a limited space when the system load rotates, and limited long-distance recognition capability. The present invention designs a highly integrated composite detection optical system, and rationally arranges and optimizes the detection structure of each module. Under the premise of ensuring high resolution and high energy utilization, the system length and volume are reduced, and the rotation angle of the servo frame in a limited space is increased.

[0005] To achieve the above objectives, the technical solution created by this invention is implemented as follows: A miniaturized three-mode composite detection optical system includes, coaxially arranged along the optical axis from object to image: a radome, a laser four-quadrant detector, a filter, a second lens, a first lens, a secondary mirror, a first infrared lens, a second infrared lens, a third infrared lens, a primary mirror, and a millimeter-wave waveguide slotted array radar. It also includes an infrared detector located at the central through-hole of the primary mirror. The target light beam is transmitted through the radome and then enters the primary mirror. The primary mirror reflects the target light beam onto the secondary mirror. The secondary mirror has a dichroic film on the side closest to the primary mirror, which separates the target light beam into laser light and infrared light. The laser light beam passes sequentially through the optical surface of the secondary mirror near the radome, the first lens, the second lens, and the filter to reach the photosensitive surface of the laser four-quadrant detector. The infrared light beam passes sequentially through the first infrared lens, the second infrared lens, and the third infrared lens to enter the infrared detector, which is located at the center of the central through-hole of the primary mirror. The millimeter-wave signal emitted by the millimeter-wave waveguide slot array radar is radiated to the target through the primary mirror and the radome in sequence, and the echo signal reflected by the target is transmitted through the radome and the primary mirror in sequence before reaching the millimeter-wave waveguide slot array radar.

[0006] Furthermore, both the millimeter-wave waveguide slot array radar and the primary mirror are ring structures, and the inner and outer diameters of the millimeter-wave waveguide slot array radar and the primary mirror are the same.

[0007] Furthermore, the expression for the light-transmitting aperture of the fairing is: ; ; in, The aperture of the fairing. Let be the radius of curvature of the optical surface of the radome on the side furthest from the laser quadrant detector. This represents the maximum rotation angle of the servo frame housing the miniaturized three-mode composite detection optical system. For the maximum field of view of a miniaturized three-mode composite detection optical system, These are intermediate parameters with no physical meaning. The aperture of the primary mirror.

[0008] Furthermore, the radome has a thickness of 5.56 mm, and the air gap between the radome and the primary mirror is 86 mm; the air gap between the primary mirror and the secondary mirror is 55.55 mm, the secondary mirror has a thickness of 4 mm, the air gap between the secondary mirror and the first lens is 0.1 mm, the first lens has a thickness of 4 mm, the air gap between the first lens and the second lens is 8.672 mm, the second lens has a thickness of 4 mm, the air gap between the second lens and the filter is 1.57 mm, the filter has a thickness of 0.7 mm, and the air gap between the filter and the laser quadrant detector is 2 mm.

[0009] Furthermore, the air gap between the secondary lens and the first infrared lens is 20mm, the thickness of the first infrared lens is 4mm, the air gap between the first infrared lens and the second infrared lens is 6mm, the thickness of the second infrared lens is 3mm, the air gap between the second infrared lens and the third infrared lens is 0.3mm, the thickness of the third infrared lens is 3mm, and the air gap between the third infrared lens and the infrared detector is 3mm.

[0010] Furthermore, the radius of curvature of the optical surface of the fairing away from the primary mirror is 100 mm, the radius of curvature of the optical surface of the fairing near the primary mirror is 94.44 mm, the vertex radius of curvature of the primary mirror is -149.655 mm, the vertex radius of curvature of the optical surface of the secondary mirror near the primary mirror is -86.759 mm, the radius of curvature of the optical surface of the secondary mirror away from the primary mirror is -131.875 mm, the vertex radius of curvature of the optical surface of the first lens near the secondary mirror is -21.923 mm, the radius of curvature of the optical surface of the first lens away from the secondary mirror is -10.637 mm, and the radius of curvature of the optical surface of the second lens near the secondary mirror is -15.017 mm. The vertex radius of curvature of the optical surface of the second lens on the side away from the secondary lens is -27.085 mm. The vertex radius of curvature of the optical surface of the first infrared lens on the side closer to the secondary lens is 18.473 mm, and the radius of curvature of the optical surface of the first infrared lens on the side away from the secondary lens is 20.725 mm. The vertex radius of curvature of the optical surface of the second infrared lens on the side closer to the secondary lens is -255.147 mm, and the radius of curvature of the optical surface of the second infrared lens on the side away from the secondary lens is 35.692 mm. The radius of curvature of the optical surface of the third infrared lens on the side closer to the secondary lens is 32.34 mm, and the vertex radius of curvature of the optical surface of the third infrared lens on the side away from the secondary lens is 68.048 mm.

[0011] Furthermore, the color separation film adopts a multilayer dielectric film system.

[0012] Furthermore, the primary mirror is made of magnesium fluoride.

[0013] Compared with the prior art, the present invention can achieve the following beneficial effects: (1) The miniaturized three-mode composite detection optical system created by the present invention adopts a common aperture design, separates laser light and infrared light by color separation through secondary mirror, and arranges millimeter waveguide slot array radar on the rear side of the primary mirror, thereby avoiding aperture competition, reducing the size of the system, reducing the weight of the system, and realizing highly integrated miniaturization.

[0014] (2) The miniaturized three-mode composite detection optical system created by the present invention utilizes a single imaging method to place the detector in the center hole of the primary mirror in the infrared detection optical path, effectively utilizing space and reducing the system length.

[0015] (3) The miniaturized three-mode composite detection optical system created by the present invention makes full use of the space between the secondary mirror and the radome, and arranges the laser quadrant detector, filter, second lens and first lens in this position, thereby shortening the overall optical path length.

[0016] (4) The miniaturized three-mode composite detection optical system created by the present invention uses a dichroic film with zinc selenide as the substrate for the secondary mirror. It transmits 1.06μm laser light with a transmittance of more than 85% and reflects 8μm to 12μm infrared light with a reflectance of more than 90%. This ensures efficient reflection of long-wave infrared light and efficient transmission of laser light, improves energy utilization efficiency, and thus improves the long-distance detection and identification capabilities of the laser detection optical path and the infrared detection optical path.

[0017] (5) The miniaturized three-mode composite detection optical system created by the present invention has a small obstruction ratio between the primary and secondary mirrors, which further improves the energy utilization efficiency and enhances the detection capability of long-distance and weak target signals.

[0018] (6) The miniaturized three-mode composite detection optical system created by the present invention has a laser spot shape that corresponds one-to-one with the blocking ratio. The outer diameter of the spot in the linear region is 2500μm, which improves the field of view in the linear region. Within the field of view in the linear region, the system distortion is small, the spot is stable and has high uniformity. The spot illuminance data and the detector received signal data are fitted with high linearity, which ensures the guidance accuracy.

[0019] (7) The miniaturized three-mode composite detection optical system created by the present invention has a large entrance pupil diameter, which can improve the energy collection capability of the laser detection optical path, enhance its signal extraction capability under complex environmental conditions, improve the temperature sensitivity of the infrared detection optical path, and at the same time, the infrared detection optical path has a long focal length, which is beneficial to improving the spatial resolution of the infrared detection optical path.

[0020] (8) The miniaturized three-mode composite detection optical system created by this invention features a millimeter-wave waveguide slot array radar and a primary mirror arranged coaxially, with consistent assembly and adjustment standards, reducing assembly and adjustment difficulty. Both have large apertures, and the primary mirror uses a low dielectric loss material to improve the gain of the millimeter-wave waveguide slot array radar and reduce the sidelobe level.

[0021] (9) The miniaturized three-mode composite detection optical system created by the present invention reduces the length and volume of the system and increases the rotation angle of the servo frame in a limited space by reasonable layout, parameter optimization and material selection, while ensuring high resolution and high energy utilization. Attached Figure Description

[0022] The accompanying drawings, which form part of this invention, are used to provide a further understanding of the invention. The illustrative embodiments and descriptions of the invention are used to explain the invention and do not constitute an undue limitation of the invention. In the drawings: Figure 1 A schematic diagram of the structure of the miniaturized three-mode composite detection optical system described in the embodiment of the present invention; Figure 2 A schematic diagram showing the relationship between the light transmission aperture and various parameters of the rectifier described in the embodiment of the present invention; Figure 3 A schematic diagram illustrating the relationship between the servo frame rotation angle and the rectifier aperture as described in an embodiment of the present invention; Figure 4 A schematic diagram of the structure of the color separation film described in the embodiments of the present invention; Figure 5 The transfer function curve of the infrared detection optical path described in the embodiment of the present invention; Figure 6 A dot diagram of the infrared detection optical path described in the embodiments of the present invention; Figure 7 The field curvature and distortion curves of the infrared detection optical path described in the embodiments of the present invention are shown.

[0023] Figure 8 A schematic diagram of the linear field of view of the laser detection optical path described in the embodiment of the present invention; Figure 9 The field curvature and distortion curves of the linear region field of view of the laser detection optical path described in the embodiments of the present invention; Figure 10 The diagram shows the linear fitting relationship between the field of view and the output signal of the laser detection optical path described in the embodiment of the present invention.

[0024] Explanation of reference numerals in the attached figures: 1. Fairing; 2. Primary mirror; 3. Secondary mirror; 4. First lens; 5. Second lens; 6. Filter; 7. Laser four-quadrant detector; 8. First infrared lens; 9. Second infrared lens; 10. Third infrared lens; 11. Infrared detector; 12. Millimeter-wave waveguide slot array radar. Detailed Implementation

[0025] 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 specific embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and do not constitute a limitation thereof.

[0026] It should be noted that, unless otherwise specified, the embodiments and features described in the present invention can be combined with each other.

[0027] In the description of this invention, it should be understood that the terms "center," "longitudinal," "lateral," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," and "outer," etc., indicating orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation on this invention. Furthermore, the terms "first," "second," etc., are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, features defined with "first," "second," etc., may explicitly or implicitly include one or more of that feature. In the description of this invention, unless otherwise stated, "a plurality of" means two or more.

[0028] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art will understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0029] The invention will now be described in detail with reference to the accompanying drawings and embodiments.

[0030] like Figure 1 As shown, this invention provides a miniaturized three-mode composite detection optical system, comprising: a radome 1, a laser four-quadrant detector 7, a filter 6, a second lens 5, a first lens 4, a secondary mirror 3, a first infrared lens 8, a second infrared lens 9, a third infrared lens 10, a primary mirror 2, and a millimeter-wave waveguide slot array radar 12, arranged coaxially along the optical axis from the object side to the image side; and an infrared detector 11 disposed at the central through-hole of the primary mirror 2. The target light beam is transmitted through the radome 1 and then enters the primary mirror 2. The primary mirror 2 reflects the target light beam onto the secondary mirror 3. The secondary mirror 3 has a dichroic film on the side of the secondary mirror 3 closest to the primary mirror 2. The dichroic film separates the target light beam into laser light and infrared light. The laser light beam passes sequentially through the optical surface of the secondary mirror 3 closest to the radome 1, the first lens 4, the second lens 5, and the filter 6 to reach the photosensitive surface of the laser quadrant detector 7. The infrared light beam passes sequentially through the first infrared lens 8, the second infrared lens 9, and the third infrared lens 10 to enter the infrared detector 11. The millimeter-wave signal emitted by the millimeter-wave waveguide slot array radar 12 is radiated to the target through the main mirror 2 and the radome 1 in sequence, and the echo signal reflected by the target is transmitted through the radome 1 and the main mirror 2 in sequence before reaching the millimeter-wave waveguide slot array radar 12.

[0031] It should be noted that this invention provides a highly integrated, miniaturized composite detection optical system that combines long-wave infrared, semi-active laser, and millimeter-wave wavelengths in a common aperture configuration, achieving high-efficiency and high-resolution accurate detection under complex environmental conditions. The specific implementation scheme is as follows: The infrared, laser, and millimeter-wave tri-mode composite detection optical system proposed in this invention includes the following components arranged coaxially from the object side to the image side along the optical axis: a radome 1, a laser four-quadrant detector 7, a filter 6, a second lens 5, a first lens 4, a secondary mirror 3, a first infrared lens 8, a second infrared lens 9, a third infrared lens 10, an infrared detector 11, a primary mirror 2, and a millimeter-wave waveguide slotted array radar 12. The millimeter-wave waveguide slotted array radar 12 is an active transceiver radar located behind the primary mirror 2, with its center opening synchronously with the primary mirror 2. The secondary mirror 3 has a dichroic film coated on its surface near the primary mirror 2, reflecting long-wave infrared light and transmitting laser light, used to separate infrared and laser light. Infrared light is transmitted through the radome 1, reflected by the primary mirror 2, and then reflected again by the optical surface of the secondary mirror 3 near the primary mirror 2. It then passes sequentially through the first infrared lens 8, the second infrared lens 9, and the third infrared lens 10 before being imaged onto the image plane of the infrared detector 11; this is the infrared detection optical path. The laser beam is transmitted through the radome 1, reflected by the primary mirror 2, and transmitted through both surfaces of the secondary mirror 3. It then passes sequentially through the first lens 4, the second lens 5, and the filter 6 before reaching the photosensitive surface of the laser quadrant detector 7. This constitutes the laser detection optical path. This invention enables the design of a highly integrated common-aperture three-mode composite detection optical system, achieving a large servo frame rotation angle while ensuring long-range detection and identification capabilities. The entire system, from the front surface of the radome 1 to the rear surface of the millimeter-wave waveguide slotted array radar 12, has a length of only 124 mm, achieving a high degree of system integration and laying the foundation for increasing the servo frame angle of the platform.

[0032] Furthermore, the overall tri-mode architecture, including the arrangement of infrared, semi-active laser, and millimeter-wave radar, adopts a large-aperture design, which can simultaneously improve the energy utilization efficiency of the three operating modes. By using a longer focal length, the long-range detection and identification capabilities of the infrared system are effectively enhanced. The overall system structure is compact, with an axial length of only 124mm, achieving high integration and miniaturization, which is beneficial for system weight reduction and can support a larger servo frame rotation range. Infrared detection utilizes single-image imaging, placing the infrared detector 11 in the center hole of the primary mirror 2, effectively utilizing space and reducing the system length.

[0033] In some embodiments, both the millimeter-wave waveguide slot array radar 12 and the primary mirror 2 are annular structures. When millimeter waves encounter the edge of an obstacle, they deviate from a straight line and bend around the obstacle, a phenomenon known as millimeter-wave diffraction. A primary purpose of the central opening in the millimeter-wave waveguide slot array radar 12 is to prevent the laser quadrant detector 7, filter 6, second lens 5, first lens 4, secondary mirror 3, first infrared lens 8, second infrared lens 9, third infrared lens 10, and infrared detector 11 from blocking the millimeter-wave signal emitted from the central portion of the millimeter-wave waveguide slot array radar 12, thus preventing millimeter-wave diffraction, which would lead to a decrease in millimeter-wave radar gain and an increase in sidelobe levels. The central opening improves gain, reduces spurious echoes, and enhances anti-interference capabilities. The inner and outer diameters of the millimeter-wave waveguide slot array radar 12 and the primary mirror 2 are identical.

[0034] In some embodiments, the obstruction ratio between the secondary mirror 3 and the primary mirror 2 is 0.43.

[0035] It should be noted that setting the obstruction ratio between the secondary mirror 3 and the primary mirror 2 to 0.43 can further improve energy utilization efficiency and enhance the ability to extract signals from long-range, weak targets.

[0036] Furthermore, the expression for the light-transmitting aperture of the fairing 1 is as follows: ; ; in, The aperture of fairing 1 is the light transmission aperture. Let be the radius of curvature of the optical surface of the fairing 1 on the side furthest from the laser quadrant detector 7. This represents the maximum rotation angle of the servo frame housing the miniaturized three-mode composite detection optical system. For the maximum field of view of a miniaturized three-mode composite detection optical system, These are intermediate parameters with no physical meaning. The aperture of the main mirror is 2.

[0037] It should be noted that a spherical fairing is used, with the front and rear surfaces of fairing 1 being concentric spheres. The radius of curvature of the front surface depends on the distance between the center of gravity of the entire tri-mode composite detection optical system and the front surface of fairing 1. To ensure that the imaging remains unchanged when the tri-mode composite detection optical system rotates at any angle under servo control, the azimuth and pitch rotation centers of the tri-mode composite detection optical system coincide with the centers of the two surfaces of fairing 1. The material of fairing 1 is multispectral zinc sulfide, which is transparent in all three operating frequency bands, and its dielectric constant in the millimeter-wave operating frequency band is [not specified]. It is 8.38, according to the formula (m takes an integer, such as 1, 2, 3, ...) It is the center wavelength of millimeter waves. (where d is the dielectric constant of multispectral zinc sulfide at that wavelength, and d is the center thickness of fairing 1) can be used to calculate that the thickness of fairing 1 is 5.56 mm. The thickness is the difference between the radii of curvature of the front and rear surfaces of fairing 1, so the radius of curvature of the rear surface is 94.44 mm. According to Figure 2 The light transmission aperture of fairing 1 The relationships between the various parameters are as follows: ; ; In the above formula: R is the light-transmitting aperture of fairing 1, which cannot exceed the diameter of the connecting carrier (190mm). R is the radius of curvature of the spherical surface of the front surface of fairing 1. This refers to the maximum rotation angle (maximum value of azimuth and elevation angles) of the servo frame of the three-mode composite detection optical system. For the maximum field of view of a miniaturized three-mode composite detection optical system, For the instantaneous light transmission half-angle of the image, This is the entrance pupil diameter, which is the aperture of primary mirror 2. Under the condition that other parameters remain unchanged, the entrance pupil diameter... The smaller the value, the larger the servo frame rotation angle, but... Reducing the optical system's length would result in energy loss across various optical modes, impacting target detection and identification. Shortening the optical system length would increase the servo frame's rotation angle; therefore, ideally, a large entrance pupil diameter and a small optical length would be achieved. To improve the resolution of the infrared detection path and the weak signal extraction capability of the laser detection path, the entrance pupil diameter... The value is taken as 110mm. The aperture of the fairing 1 is derived using the above two formulas. Calculated by the following formula: ; According to the above formula, we get Figure 3When the radius of rotation (center of gravity position) of the three-mode composite detection optical system is different, the aperture of the radome 1 and the achievable servo frame rotation angle are different. Under the constraint of a maximum aperture of 190mm, the smaller the radius of curvature R of the front surface of the radome 1, the larger the achievable scanning frame angle. However, the radius of the front surface of the radome 1 cannot be less than half the diameter of the carrier, 95mm (otherwise it cannot be connected to the carrier). In the infrared detection optical path, the distance between the reflective surface of the primary mirror 2 and the surface of the secondary mirror 3 near the radome is 59.55mm. The center of gravity is set on the heaviest primary mirror 2 in the entire system, and the distance between the center of gravity and the front surface of the primary mirror 2 is 8.44mm. According to the dimensional chain 95mm-8.44mm-59.55mm=27.01mm, it means that there is at least 27.01mm of space between the refractive surface of the secondary mirror 3 and the radome 1. The laser detection optical path effectively utilizes this space, avoids the complexity of the optical path behind the primary mirror 2, and makes the entire system more compact. Based on the actual optical path dimensions, the center of gravity of this system is determined to be 100mm from the front surface of the radome 1 (the surface of the radome 1 furthest from the main mirror 2), meaning the radius of curvature R of the front surface of the radome 1 is 100mm. At this point, when the scanning frame angle is 35°, the aperture is 190mm. After comprehensively balancing various coupling relationships, the system parameters reach the optimal solution.

[0038] Furthermore, the thickness of the fairing 1 is 5.56 mm, the air gap between the fairing 1 and the primary mirror 2 is 86 mm; the air gap between the primary mirror 2 and the secondary mirror 3 is 55.55 mm, the thickness of the secondary mirror 3 is 4 mm, the air gap between the secondary mirror 3 and the first lens 4 is 0.1 mm, the thickness of the first lens 4 is 4 mm, the air gap between the first lens 4 and the second lens 5 is 8.672 mm, the thickness of the second lens 5 is 4 mm, the air gap between the second lens 5 and the filter 6 is 1.57 mm, the thickness of the filter 6 is 0.7 mm, and the air gap between the filter 6 and the laser quadrant detector 7 is 2 mm.

[0039] Furthermore, the air gap between the secondary mirror 3 and the first infrared lens 8 is 20mm, the thickness of the first infrared lens 8 is 4mm, the air gap between the first infrared lens 8 and the second infrared lens 9 is 6mm, the thickness of the second infrared lens 9 is 3mm, the air gap between the second infrared lens 9 and the third infrared lens 10 is 0.3mm, the thickness of the third infrared lens 10 is 3mm, and the air gap between the third infrared lens 10 and the infrared detector 11 is 3mm.

[0040] Furthermore, the radius of curvature of the optical surface of the fairing 1 on the side away from the primary mirror 2 is 100 mm, the radius of curvature of the optical surface of the fairing 1 on the side closer to the primary mirror 2 is 94.44 mm, the vertex radius of curvature of the primary mirror 2 is -149.655 mm, the vertex radius of curvature of the optical surface of the secondary mirror 3 on the side closer to the primary mirror 2 is -86.759 mm, the radius of curvature of the optical surface of the secondary mirror 3 on the side away from the primary mirror 2 is -131.875 mm, the vertex radius of curvature of the optical surface of the first lens 4 on the side closer to the secondary mirror 3 is -21.923 mm, the radius of curvature of the optical surface of the first lens 4 on the side away from the secondary mirror 3 is -10.637 mm, and the radius of curvature of the optical surface of the second lens 5 on the side closer to the secondary mirror 3 is -15.017 mm. The vertex radius of curvature of the optical surface of the second lens 5 on the side away from the secondary lens 3 is -27.085 mm. The vertex radius of curvature of the optical surface of the first infrared lens 8 on the side close to the secondary lens 3 is 18.473 mm, and the radius of curvature of the optical surface of the first infrared lens 8 on the side away from the secondary lens 3 is 20.725 mm. The vertex radius of curvature of the optical surface of the second infrared lens 9 on the side close to the secondary lens 3 is -255.147 mm, and the radius of curvature of the optical surface of the second infrared lens 9 on the side away from the secondary lens 3 is 35.692 mm. The radius of curvature of the optical surface of the third infrared lens 10 on the side close to the secondary lens 3 is 32.34 mm, and the vertex radius of curvature of the optical surface of the third infrared lens 10 on the side away from the secondary lens 3 is 68.048 mm.

[0041] In some embodiments, the color separation film employs a layered dielectric film system.

[0042] It should be noted that the reflecting surface of the primary mirror 2 is an even-order aspherical surface. To achieve near-equal optical path transmission of millimeter waves, the surface of the primary mirror 2 closest to the millimeter-wave waveguide slot array radar 12 has the same thickness as the reflecting surface of the primary mirror 2. The primary mirror 2 is made of magnesium fluoride, and its dielectric constant in the millimeter-wave operating band is... It is 5.28, according to the formula. The thickness of primary mirror 2 can be calculated to be 10.51 mm. The outer diameter of primary mirror 2 is 110 mm, and the diameter of the central opening is 47 mm. An infrared (uncooled) detector can be placed through the central opening, making full use of space and shortening the optical path length.

[0043] like Figure 4 As shown, the surface of the secondary mirror 3 near the primary mirror 2 is an even-order aspherical surface. This surface is coated with a dichroic film, which can be achieved using a dielectric film of alternating layers of 12-30 layers of ytterbium fluoride and zinc sulfide, or a metal-dielectric induced film, using silver as the metal and zinc sulfide as the dielectric. This film system achieves a long-wave infrared reflectivity ≥90% and a light transmittance of ≥85% at 1.06 μm.

[0044] Furthermore, Figure 4The design data for the color separation film is as follows: the substrate is zinc selenide, and 14 layers of alternating ytterbium fluoride and zinc sulfide dielectric films are set upwards from the substrate. The first dielectric film is ytterbium fluoride with a physical thickness of 1635.58 nm, the second dielectric film is zinc sulfide with a physical thickness of 1599.77 nm, the third dielectric film is ytterbium fluoride with a physical thickness of 2395.53 nm, the fourth dielectric film is zinc sulfide with a physical thickness of 1184.94 nm, the fifth dielectric film is ytterbium fluoride with a physical thickness of 1834.94 nm, the sixth dielectric film is zinc sulfide with a physical thickness of 1167.6 nm, and the seventh dielectric film is... The first dielectric layer is ytterbium fluoride with a physical thickness of 1743.1 nm; the second dielectric layer is zinc sulfide with a physical thickness of 1139 nm; the third dielectric layer is ytterbium fluoride with a physical thickness of 1605.45 nm; the fourth dielectric layer is zinc sulfide with a physical thickness of 1033.89 nm; the fifth dielectric layer is ytterbium fluoride with a physical thickness of 1983.98 nm; the sixth dielectric layer is zinc sulfide with a physical thickness of 598.83 nm; the seventh dielectric layer is ytterbium fluoride with a physical thickness of 1189.89 nm; and the eighth dielectric layer is zinc sulfide with a physical thickness of 926.39 nm.

[0045] In some embodiments, the infrared detector 11 is disposed at the center of the central through hole of the main mirror 2. The main mirror 2 and the infrared detector 11 are fixed by a lens barrel, which mates with the central hole of the main mirror 2. The first infrared lens 8, the second infrared lens 9, the third infrared lens 10, and the infrared detector 11 are fixed inside the lens barrel.

[0046] In some embodiments, the primary mirror 2 is made of magnesium fluoride, which has a small dielectric constant and dielectric loss tangent.

[0047] It should be noted that the material selection and thickness determination of the primary mirror 2 are related to the dielectric constant, dielectric loss and manufacturing process of the millimeter-wave waveguide slot array radar 12, and the thickness is determined based on the dielectric constant.

[0048] Furthermore, the secondary mirror 3 of this invention is made of zinc selenide, and a dichroic film is deposited on its surface near the primary mirror 2. It transmits 1.06μm laser light and reflects 8μm to 12μm infrared light, with a transmittance greater than or equal to 85% and a reflectance greater than or equal to 90%, further improving energy efficiency. The laser spot corresponds one-to-one with the primary and secondary mirrors 3, resulting in high spot uniformity. Within the linear field of view, the spot illuminance data is fitted with the detector received signal data, exhibiting high linearity and ensuring detection accuracy.

[0049] Secondary mirror 3 can also use multispectral zinc sulfide, while primary mirror 2 can use fused silica, etc.

[0050] The primary mirror 2 adopts a central opening structure with a light transmission aperture of 110mm. The secondary mirror 3 has an outer diameter of 47mm. The obstruction ratio of the catadioptric system composed of the secondary mirror 3 and the primary mirror 2 is 0.43.

[0051] The millimeter-wave radar antenna section adopts a planar form and is a waveguide slot array antenna. The antenna is a ring with a central opening, and its outer diameter and opening diameter are comparable to the outer diameter and central opening diameter of the primary mirror 2.

[0052] The fairing 1 is made of multispectral zinc sulfide (CVD ZNS), the primary mirror 2 is made of hot-pressed magnesium fluoride, the secondary mirror 3 is made of zinc selenide (ZnSe), the first lens 4 is made of H-ZLAF92, the second lens 5 is made of H-ZLAF92, and the filter 6 is made of fused silica (Silica). The first infrared lens 8 is made of infrared zinc sulfide (ZNS-IR), the second infrared lens 9 is made of infrared zinc sulfide (ZNS-IR), and the third infrared lens 10 is made of germanium (GE-LONG).

[0053] The ratio of the focal length of the secondary lens 3 to the focal length of the laser detection optical path ranges from 2.5 to 3.5; the ratio of the focal length of the first lens 4 to the focal length of the laser detection optical path ranges from -0.35 to -0.25; the ratio of the focal length of the second lens 5 to the focal length of the laser detection optical path ranges from 0.3 to 0.4; the ratio of the focal length of the first infrared lens 8 to the focal length of the infrared detection optical path ranges from 0.67 to 0.77; the ratio of the focal length of the second infrared lens 9 to the focal length of the infrared detection optical path ranges from -0.31 to -0.21; and the ratio of the focal length of the third infrared lens 10 to the focal length of the infrared detection optical path ranges from 0.14 to 0.24.

[0054] The light transmission path of the infrared detection optical path of the present invention is as follows: the infrared light in the 8μm to 12μm band emitted by the target radiation passes through the spherical rectifier 1 and reaches the main mirror 2. After being reflected by the main mirror 2, it reaches the secondary mirror 3. After being reflected by the surface of the secondary mirror 3 near the main mirror, it passes through the first infrared lens 8, the second infrared lens 9 and the third infrared lens 10 and converges onto the image plane of the infrared detector 11.

[0055] The light transmission path of the laser detection optical path of the present invention is as follows: the laser light in the 1.064μm band reflected by the target passes through the spherical rectifier 1 and reaches the primary mirror 2. After being reflected by the primary mirror 2, it reaches the secondary mirror 3. After passing through the secondary mirror 3, the first lens 4, the second lens 5, and the filter 6, it converges to the photosensitive surface of the laser four-quadrant detector 7.

[0056] The light transmission path of the radar subsystem of the present invention is as follows: the millimeter-wave signal emitted by the millimeter-wave waveguide slot array radar 12 is directly transmitted through the main mirror 2, then passes through the radome 1, illuminates the target and is reflected, and the reflected echo signal is transmitted through the radome 1 and the main mirror 2 to reach the millimeter-wave waveguide slot array radar 12.

[0057] Table 1 shows the technical specifications used in implementing the infrared detection optical path of this invention. The F-number of the infrared detection optical path is calculated as f / D, where f is the focal length of the infrared detection optical path and D is the diameter of the entrance pupil. The effective F-number of the infrared detection optical path is the ratio of the effective entrance pupil diameter to the focal length. 有效 = D0 is the aperture of the primary mirror 2, D1 is the diameter of the central opening of the primary mirror 2, and also the outer diameter of the secondary mirror 3. The effective entrance pupil diameter is... For the laser and infrared detection optical paths, the primary mirror aperture D0 is 110mm, and the central aperture diameter is 47mm, so the effective entrance pupil diameter is 99.45mm. Table 2 shows the relevant specifications for the laser detection optical path, and Table 3 shows the relevant specifications for the millimeter-wave waveguide slot array radar 12.

[0058] Table 1

[0059] Table 2

[0060] Table 3

[0061] Tables 4 and 5 list detailed data for embodiments of the present invention, including the surface shape, radius of curvature, thickness, and material of each lens. The units for the radius of curvature and thickness of the lenses are mm. In Tables 4 and 5, the radius of curvature of even-order aspherical surfaces refers to the radius of curvature at the vertex, which is the radius of curvature at the intersection of the lens surface and the optical axis. The principle for determining the positive or negative value of the radius of curvature in Tables 4 and 5 is: taking the intersection of the surface and the principal optical axis as the starting point and the center of the surface as the ending point. If the direction of the connecting line is the same as the direction of light propagation, it is positive; otherwise, it is negative. If the surface is planar, the radius of curvature is infinite. The "thickness" in Tables 4 and 5 gives the distance between two adjacent surfaces on the optical axis. The principle for determining its positive or negative value is: taking the vertex of the current surface as the starting point and the vertex of the next surface as the ending point. If the direction of the connecting line is the same as the direction of light propagation, it is positive; otherwise, it is negative. If the material between two surfaces is the lens material, the corresponding thickness represents the lens thickness; if there is no material between two surfaces, it represents the air gap between the two lenses.

[0062] Table 4

[0063] Table 5

[0064] In the infrared, laser, and millimeter-wave tri-mode composite detection optical system, the reflecting surface of the primary mirror 2, the surface of the secondary mirror 3 near the primary mirror 2, the surface of the first lens 4 near the secondary mirror 3, the surface of the second lens 5 near the radome 1, the surface of the first infrared lens 8 near the secondary mirror 3, the surface of the second infrared lens 9 near the secondary mirror 3, and the surface of the third infrared lens 10 near the primary mirror 2 are all even-order aspherical surfaces. The surface shape equations of each of these aspherical surfaces are as follows:

[0065] Where z is the distance vector from the vertex of the aspherical surface at a height of r along the optical axis, c is the vertex curvature (c = 1 / R), R represents the vertex radius of curvature of the lens surface, r is the radial coordinate perpendicular to the optical axis, and k is the quadratic constant. For fourth-order aspherical coefficients, For sixth-order aspherical coefficients, These are the eighth-order aspherical coefficients.

[0066] The aspheric coefficients of even-order aspheric surfaces in this invention are expressed in scientific notation, for example, 3.523E-08 represents 3.523 × 10⁻⁶. -8 The corresponding solution results are shown in Table 6.

[0067] Table 6

[0068] After simulation using optical design software, such as Figure 5 As shown, the transfer function of a long-wavelength uncooled detector with a pixel size of 12µm at a spatial frequency of 42lp / mm is close to 0.2; Figure 6 As shown, except for the maximum field of view corresponding to the diagonal, the diameter of the blur spot in other fields of view of the infrared detection optical path is much smaller than the diameter of the Airy disk. Figure 7 The field curvature and distortion curves of the infrared detection optical path are shown below. Figure 7 As can be seen, Y+ is the positive direction of the field of view, and the edge field of view distortion of the infrared detection optical path is less than 1.5%; Figure 8 This is a schematic diagram of the linear field of view of the laser detection optical path, from... Figure 8 As can be seen, by adjusting the photosensitive surface to a suitable defocus position, the light spot size within the linear field of view is consistent and the energy is uniform. Figure 9 The field curvature and distortion curves of the linear field of view of the laser probe optical path are shown below. Figure 9 It can be seen that the absolute value of the linear field distortion of the laser detection optical path is less than 0.3%.

[0069] The principle of the semi-active laser detection optical path is to characterize the target's position information by analyzing the energy distribution of the diffusely reflected laser signal on the laser four-quadrant detector 7, and then calculating the current value using a sum-difference formula. The sum-difference curve formula is as follows: ; in, This represents the illuminance value of the upper left quadrant response of the laser four-quadrant detector 7. This represents the illuminance value of the upper right quadrant response of the laser four-quadrant detector 7. This represents the illuminance value of the lower left quadrant response of the laser four-quadrant detector 7. This represents the illuminance value of the lower right quadrant response of the laser four-quadrant detector 7. This is the proportionality coefficient. The current value of the laser four-quadrant detector 7 is calculated using the sum and difference formula, representing the target's vertical and horizontal position information off-center on the laser four-quadrant detector 7. It can be obtained by the same method.

[0070] Data analysis software was used to read the illuminance values ​​of the laser probe beam within each field of view in the linear region, and the current values ​​of the detector response in each field of view in the linear region were simulated and calculated using the sum and difference formula. As shown in Table 7, the current values ​​are fitted to each field of view in the linear region. Figure 10 It is a fitted curve, derived from Figure 10 It can be seen that within the linear region of ±1.75°, the coefficient of determination R of the fitted curve is... 2 The linearity is 0.993, indicating good linearity and high linearity. The spot energy distribution of the laser detection optical path can meet the usage requirements.

[0071] Table 7

[0072] It should be understood that the various forms of processes shown above can be used to reorder, add, or delete steps. For example, the steps described in this invention disclosure can be executed in parallel, sequentially, or in different orders, as long as the desired result of the technical solution disclosed in this invention can be achieved, and this is not limited herein.

[0073] The specific embodiments described above do not constitute a limitation on the scope of protection of this invention. Those skilled in the art should understand that various modifications, combinations, sub-combinations, and substitutions can be made according to design requirements and other factors. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of this invention should be included within the scope of protection of this invention.

Claims

1. A miniaturized tri-mode composite detection optical system, characterized in that: The system includes, along the optical axis from the object side to the image side, the following components are coaxially arranged: a radome, a laser four-quadrant detector, a filter, a second lens, a first lens, a secondary mirror, a first infrared lens, a second infrared lens, a third infrared lens, a primary mirror, and a millimeter-wave waveguide slotted array radar. It also includes an infrared detector located at the central through-hole of the primary mirror. The target light beam is transmitted through the radome and then enters the primary mirror. The primary mirror reflects the target light beam onto the secondary mirror. The secondary mirror has a dichroic film on the side closest to the primary mirror, which separates the target light beam into laser light and infrared light. The laser light beam passes sequentially through the optical surface of the secondary mirror near the radome, the first lens, the second lens, and the filter to reach the photosensitive surface of the laser four-quadrant detector. The infrared light beam passes sequentially through the first infrared lens, the second infrared lens, and the third infrared lens to reach the photosensitive surface of the infrared detector, which is located at the center of the central through-hole of the primary mirror. The expression for the light-transmitting aperture of the fairing is: ； ； in, The aperture of the fairing. Let be the radius of curvature of the optical surface of the radome on the side furthest from the laser quadrant detector. This represents the maximum rotation angle of the servo frame housing the miniaturized three-mode composite detection optical system. For the maximum field of view of a miniaturized three-mode composite detection optical system, These are intermediate parameters with no physical meaning. The aperture of the primary mirror; The millimeter-wave signal emitted by the millimeter-wave waveguide slot array radar is radiated to the target through the primary mirror and the radome in sequence, and the echo signal reflected by the target is transmitted through the radome and the primary mirror in sequence before reaching the millimeter-wave waveguide slot array radar.

2. The miniaturized tri-mode composite detection optical system according to claim 1, characterized in that: Both the millimeter-wave waveguide slot array radar and the primary mirror are ring structures, and their inner and outer diameters are the same.

3. The miniaturized tri-mode composite detection optical system according to claim 1, characterized in that: The fairing has a thickness of 5.56 mm, and the air gap between the fairing and the primary mirror is 86 mm; the air gap between the primary mirror and the secondary mirror is 55.55 mm, the secondary mirror has a thickness of 4 mm, the air gap between the secondary mirror and the first lens is 0.1 mm, the first lens has a thickness of 4 mm, the air gap between the first lens and the second lens is 8.672 mm, the second lens has a thickness of 4 mm, the air gap between the second lens and the filter is 1.57 mm, the filter has a thickness of 0.7 mm, and the air gap between the filter and the laser four-quadrant detector is 2 mm.

4. The miniaturized tri-mode composite detection optical system according to claim 1, characterized in that: The air gap between the secondary lens and the first infrared lens is 20 mm, the thickness of the first infrared lens is 4 mm, the air gap between the first infrared lens and the second infrared lens is 6 mm, the thickness of the second infrared lens is 3 mm, the air gap between the second infrared lens and the third infrared lens is 0.3 mm, the thickness of the third infrared lens is 3 mm, and the air gap between the third infrared lens and the infrared detector is 3 mm.

5. The miniaturized tri-mode composite detection optical system according to claim 1, characterized in that: The radius of curvature of the optical surface of the fairing away from the primary mirror is 100 mm, and the radius of curvature of the optical surface of the fairing close to the primary mirror is 94.44 mm. The vertex radius of curvature of the primary mirror is -149.655 mm. The vertex radius of curvature of the optical surface of the secondary mirror close to the primary mirror is -86.759 mm, and the radius of curvature of the optical surface of the secondary mirror away from the primary mirror is -131.875 mm. The vertex radius of curvature of the optical surface of the first lens close to the secondary mirror is -21.923 mm, and the radius of curvature of the optical surface of the first lens away from the secondary mirror is -10.637 mm. The radius of curvature of the optical surface of the second lens close to the secondary mirror is -15.017 mm. The vertex radius of curvature of the optical surface of the second lens on the side away from the secondary lens is -27.085 mm. The vertex radius of curvature of the optical surface of the first infrared lens on the side closer to the secondary lens is 18.473 mm. The radius of curvature of the optical surface of the first infrared lens on the side away from the secondary lens is 20.725 mm. The vertex radius of curvature of the optical surface of the second infrared lens on the side closer to the secondary lens is -255.147 mm. The radius of curvature of the optical surface of the second infrared lens on the side away from the secondary lens is 35.692 mm. The radius of curvature of the optical surface of the third infrared lens on the side closer to the secondary lens is 32.34 mm. The vertex radius of curvature of the optical surface of the third infrared lens on the side away from the secondary lens is 68.048 mm.

6. The miniaturized tri-mode composite detection optical system according to claim 1, characterized in that: The color separation membrane uses a multilayer dielectric membrane system.

7. The miniaturized tri-mode composite detection optical system according to claim 1, characterized in that: The primary mirror is made of magnesium fluoride.

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