A moving target measuring optical system and a measuring method

Abstract

The application belongs to an optical system, and aims at the technical problems that when the trajectory of an aerial target is measured, only intersection measurement can be performed, a single theodolite cannot perform distance measurement, and measurement is inconvenient and calculation is complex, and provides a moving target measurement optical system and a measurement method, which comprise a main optical system, a laser ranging receiving correction mirror group, a visible light collimating mirror group, a visible light imaging mirror group and a mid-wave infrared projection mirror group. A structure form of a laser ranging receiving light path, visible light measurement and infrared measurement is adopted, single station angle measurement, distance measurement and temperature distribution measurement are realized, and then single station moving target trajectory measurement is completed. The main mirror and the secondary mirror of the Cassegrain mirror group used by visible light imaging, mid-wave infrared capture measurement and laser ranging reception are shared, high resolution imaging, high precision angle measurement and laser ranging without parallax are realized, and the co-axiality can meet the requirements of long focal length high definition imaging, long distance high precision angle measurement and long distance ranging.

Description

Technical Field

[0001] This application pertains to an optical system, specifically relating to an optical system and method for measuring moving targets. Background Technology

[0002] An optoelectronic theodolite is a large-scale optical measuring device that automatically tracks and measures moving targets. It is suitable for measuring the trajectory of moving targets with long aerial trajectory segments and can obtain reliable and accurate position and velocity parameters.

[0003] Currently, when using photoelectric theodolites to perform high-precision measurements on moving targets, two or more theodolites are distributed at a certain distance and at a certain angle to the target. The measurement data are then combined to simultaneously solve for the target's position information (angle and distance) in the air, achieving the purpose of tracking measurement. This is the principle of photoelectric theodolite intersection measurement. A single theodolite can only measure the target's elevation and pitch angles; therefore, a single theodolite cannot measure the trajectory of an aerial target. Summary of the Invention

[0004] This application addresses the technical problem that current methods for measuring the trajectory of aerial targets only allow for intersection measurements, and a single theodolite cannot perform distance measurements, leading to inconvenient measurements and complex calculations. It provides an optical system and method for measuring moving targets.

[0005] To achieve the above objectives, this application adopts the following technical solution:

[0006] In a first aspect, this application proposes a moving target measurement optical system, including a main optical system, a laser rangefinder receiving and correction lens group, a visible light collimating lens group, a visible light imaging lens group, and a mid-wave infrared projection lens group;

[0007] The main optical system includes a Cassegrain lens group and a spectral beam splitter; light rays incident parallel to the optical axis are incident by the primary mirror of the Cassegrain lens group; the spectral beam splitter is located in front of the primary image of the secondary mirror of the Cassegrain lens group, so as to reflect the visible light path and transmit the laser light path.

[0008] After the laser beam is incident on the laser ranging receiver correction mirror group, it converges to the detector target surface to calculate the distance from the moving target to the measuring optical system.

[0009] After the visible light path is incident on the visible light collimating lens group, the visible light path is turned to be parallel to the optical axis and the visible light path is located in the second layer above the optical axis;

[0010] The visible light path located in the second layer is incident on the visible light imaging lens group and converges to the camera target surface to identify and track moving targets, determine the angle between the moving target and the line of sight of the measurement optical system, and combine the distance between the moving target and the measurement optical system to determine the position of the target in two-dimensional space.

[0011] The mid-wave infrared light path transmitted through the secondary mirror of the Cassegrain lens group is parallel to the optical axis after being deflected and is located in the second layer above the optical axis.

[0012] The mid-wave infrared light path located in the second layer is incident on the mid-wave infrared projection lens group and imaged on the target surface of the thermal imager, which is used to capture and track the target and determine the temperature distribution of the moving target.

[0013] Furthermore, the main optical system also includes a first folding-axis mirror and a second folding-axis mirror;

[0014] The mid-wave infrared light path transmitted through the secondary mirror of the Cassegrain lens group is parallel to the optical axis after being deflected by the first and second folding mirrors in sequence.

[0015] Furthermore, the laser ranging receiver correction lens group includes a planar correction plate, a positive optical power bending image plane lens, and a first positive optical power biconvex lens arranged sequentially along the laser optical path; the laser optical path compensates for the astigmatism introduced by the spectral beam splitter through the planar correction plate, and then converges sequentially through the positive optical power bending image plane lens and the positive optical power biconvex lens.

[0016] Furthermore, the visible light collimating lens group includes a second positive power biconvex lens, a first meniscus lens, a negative power biconcave lens, a negative power cemented lens, a second meniscus lens, and a third folded-axis reflector arranged sequentially along the visible light path;

[0017] The first meniscus lens is a positive optical power meniscus lens that bends toward the parallel optical path, and the second meniscus lens is a meniscus lens that bends toward the primary image plane.

[0018] Furthermore, the visible light imaging lens group includes a third meniscus lens, a fourth meniscus lens, a third positive power biconvex lens, a negative power biconcave lens, a fifth meniscus lens, and a sixth meniscus lens arranged sequentially along the visible light path located in the second layer.

[0019] The third meniscus lens is a positive power meniscus lens bent towards the image side, the fourth meniscus lens is a negative power meniscus lens bent towards the image side, the fifth meniscus lens is a positive power meniscus lens bent towards the image side, and the sixth meniscus lens is a positive power meniscus lens bent towards the image side.

[0020] Furthermore, the mid-wave infrared projection lens group includes a first silicon lens, a negative optical power biconcave germanium lens, a positive optical power zinc sulfide lens bent towards the image plane, and a second silicon lens with positive optical power bent towards the image plane, arranged sequentially along the mid-wave infrared optical path located in the second layer.

[0021] Furthermore, the primary mirror of the Cassegrain lens group is a concave parabolic mirror, the secondary mirror of the Cassegrain lens group is a convex hyperboloid spectral splitter, and at least one of the first positive power biconvex lens, the fourth meniscus lens, and the negative power biconcave lens has an aspherical surface type.

[0022] Methods for calculating the sag of parabolic, hyperboloid, and aspherical surfaces include:

[0023]

[0024] in, Indicates the height of the arrow. Indicates curvature. r Indicates the radius of the ring. Denotes the coefficient of the quadratic term. Represents the coefficients of a fourth-order aspheric surface. Represents the 6th order aspheric coefficient. Represents the 8th order aspheric coefficient. This represents the 10th order aspheric coefficient.

[0025] Furthermore, the focal length of the visible light imaging system on which the camera target surface is located is 4500mm, and the F number is 10;

[0026] The focal length of the mid-wave infrared measurement system on which the thermal imager target surface is located is 900mm, and the F-number is 2.

[0027] The receiving focal length of the laser rangefinder on which the detector target is located is 550mm.

[0028] Secondly, this application proposes a moving target measurement method, based on the aforementioned moving target measurement optical system, comprising:

[0029] The laser beam and visible light are respectively directed onto the moving target, and the reflected laser and visible light are incident on the primary mirror of the Cassegrain lens group;

[0030] It also causes the mid-wave infrared radiation emitted by the moving target to be incident on the primary mirror of the Cassegrain lens group.

[0031] Furthermore, it also includes:

[0032] The distance from the moving target to the measuring optical system is calculated based on the laser signal in the laser optical path converged by the detector target surface.

[0033] The visible light image is obtained by the visible light path converged by the camera target surface, the moving target is identified and tracked, the angle between the moving target and the line of sight of the measurement optical system is determined, and the position of the target in two-dimensional space is determined by combining the distance of the moving target to the measurement optical system.

[0034] Mid-wave infrared images are obtained by focusing the mid-wave infrared light path on the target surface of the thermal imager, capturing and tracking the target, and determining the temperature distribution of the moving target.

[0035] Compared with the prior art, this application has the following beneficial effects:

[0036] This application proposes an optical system for measuring moving targets, comprising a main optical system, a laser ranging and receiving correction mirror group, a visible light collimating mirror group, a visible light imaging mirror group, and a mid-wave infrared projection mirror group. It adopts a structure where the laser ranging and receiving optical path, visible light measurement, and infrared measurement share a common aperture, enabling simultaneous angle, distance, and temperature distribution measurement at a single station, thereby completing the trajectory measurement of a single-station moving target. Visible light imaging, mid-wave infrared acquisition and measurement, and laser ranging and receiving share the primary and secondary mirrors of the Cassegrain mirror group, achieving high-resolution imaging, high-precision angle measurement, and parallax-free, coaxial laser ranging. It can simultaneously meet the requirements of long-focal-length high-definition imaging, long-distance high-precision angle measurement, and long-distance distance measurement. The entire system has a compact structure, good imaging quality, high energy concentration, simple structure, and high stability.

[0037] This application also proposes a method for measuring moving targets, which possesses all the advantages of the aforementioned optical system for measuring moving targets. Attached Figure Description

[0038] To more clearly illustrate the technical solutions of the embodiments of this application, the accompanying drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of this application and should not be regarded as a limitation of the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0039] Figure 1 This is a schematic diagram of one embodiment of the moving target measurement optical system of this application;

[0040] Figure 2 This is an MTF curve of a visible light imaging optical system with a spatial frequency of 50 lp / mm in an embodiment of this application.

[0041] Figure 3 This is a dot diagram of the visible light imaging optical system in the embodiments of this application;

[0042] Figure 4 This is an MTF curve of the mid-wave infrared measurement optical system with a spatial frequency of 33 lp / mm in the embodiments of this application;

[0043] Figure 5 This is a dot diagram of the mid-wave infrared measurement optical system in the embodiments of this application;

[0044] Figure 6 This is a diagram showing the energy curve of the enclosing circle of the laser ranging and receiving optical system in the embodiments of this application.

[0045] Among them: 1-primary mirror, 2-secondary mirror, 3-spectral beam splitter, 4-first folded-axis mirror, 5-second folded-axis mirror, 6-planar correction plate, 7-positive power curved image plane lens, 8-first positive power biconvex lens, 9-second positive power biconvex lens, 10-first meniscus lens, 11-first negative power biconcave lens, 12-negative power cemented lens, 13-second meniscus lens, 14-third folded-axis mirror, 15-third meniscus lens, 16-fourth meniscus lens, 17-third positive power biconvex lens, 18-second negative power biconcave lens, 19-fifth meniscus lens, 20-sixth meniscus lens, 21-first silicon lens, 22-biconcave germanium lens, 23-zinc sulfide lens, 24-second silicon lens. Detailed Implementation

[0046] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. The components of the embodiments of this application described and shown in the accompanying drawings can generally be arranged and designed in various different configurations.

[0047] Therefore, the following detailed description of the embodiments of this application provided in the accompanying drawings is not intended to limit the scope of the claimed application, but merely to illustrate selected embodiments of the application. All other embodiments obtained by those skilled in the art based on the embodiments of this application without inventive effort are within the scope of protection of this application.

[0048] It should be noted that similar labels and letters in the following figures indicate similar items. Therefore, once an item is defined in one figure, it does not need to be further defined and explained in subsequent figures.

[0049] In the description of the embodiments of this application, it should be noted that if terms such as "upper," "lower," "horizontal," or "inner" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, or the orientation or positional relationship commonly used when the product of the invention is in use, they are only for the convenience of describing this application 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 application. In addition, terms such as "first" and "second" are only used to distinguish descriptions and should not be construed as indicating or implying relative importance.

[0050] Furthermore, the use of the term "horizontal" does not imply that the component must be absolutely horizontal, but rather that it can be slightly tilted. For example, "horizontal" simply means that its direction is more horizontal than "vertical," and does not mean that the structure must be completely horizontal, but can be slightly tilted.

[0051] In the description of the embodiments of this application, it should also be noted that, unless otherwise explicitly specified and limited, the terms "set," "install," "connect," and "link" 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 can understand the specific meaning of the above terms in this application according to the specific circumstances.

[0052] As a high-precision optical measuring device, the photoelectric theodolite plays a vital role in aviation, aerospace, and astronomical observation. However, due to limitations in its measurement principle, a single theodolite can only measure the elevation and pitch angles of a target, but cannot directly measure the actual distance between the moving target and the theodolite. Therefore, relying solely on data from a single theodolite cannot accurately depict the trajectory of an aerial target, as the lack of distance information leads to inaccurate position calculations. To address this issue, photoelectric theodolite intersection measurement technology has emerged. The principle of photoelectric theodolite intersection measurement is based on the collaborative work of multiple theodolites. By observing the same moving target from multiple angles and directions, the precise position information of the target in the air can be comprehensively calculated.

[0053] However, existing intersection measurement methods have the following drawbacks:

[0054] (1) High computational complexity. Intersection surveying usually requires solving multiple equations simultaneously to obtain the position information of a moving target, involving complex mathematical calculations and data processing. As the number of measurement points increases and the measurement accuracy improves, the computational workload will increase significantly.

[0055] (2) High error accumulation. The error of each measuring device may affect the final result. Since it is necessary to integrate the measurement data of multiple devices, these errors may accumulate and lead to a decrease in the accuracy of the final result.

[0056] (3) There are many restrictions on station placement. The accuracy and reliability of intersection measurement are affected by the location of the measurement equipment. If the station placement is unreasonable, it may lead to an increase in measurement error, or even make it impossible to carry out effective intersection measurement.

[0057] (4) High requirements for data synchronization. In intersection measurement, it is necessary to ensure that the data of multiple measuring devices are synchronized in time. If there is a problem with data synchronization, it may lead to an increase in the error of the measurement results, or even make it impossible to carry out effective intersection measurement.

[0058] Based on the problems existing in the measurement and intersection measurement of a single theodolite, this application proposes an optical system and measurement method for measuring moving targets. The following is a detailed description of this application in conjunction with the embodiments and accompanying drawings.

[0059] As one embodiment of the moving target measurement optical system of this application, it may include a main optical system, a laser rangefinder receiving and correction lens group, a visible light collimating lens group, a visible light imaging lens group, and a mid-wave infrared projection lens group.

[0060] The primary optical system includes a Cassegrain lens group and a spectral beam splitter 3. Light rays incident parallel to the optical axis are incident through the primary mirror 1 of the Cassegrain lens group. The spectral beam splitter 3 is located in front of the primary image of the secondary mirror 2 of the Cassegrain lens group, reflecting visible light and transmitting laser light. It should be noted that the working principle of the Cassegrain lens group is as follows: light rays incident parallel to the optical axis are first reflected by the concave parabolic primary mirror 1, converging at a focal point, which is also a focal point of the convex hyperboloid secondary mirror 2. Then, the secondary mirror 2 reflects these rays to another focal point, which is the Cassegrain focal point, where the observer or imaging device can receive the light. The spectral beam splitter 3 is located in front of the primary image of the secondary mirror 2 of the Cassegrain lens group, and its function is to selectively reflect visible light and transmit laser light. In this way, visible light and laser light can be processed separately in the same optical system.

[0061] The laser beam, after being incident on the laser ranging receiver correction mirror assembly, is converged onto the detector target surface to calculate the distance from the moving target to the measurement optical system. The laser ranging receiver correction mirror assembly can correct and focus the laser beam, ultimately converging it onto the detector target surface. The detector then calculates the distance from the moving target to the measurement optical system based on the received laser signal.

[0062] The visible light path, after being incident on the visible light collimating lens group, is redirected to be parallel to the optical axis and positioned in a second layer above the optical axis. This second-layer visible light path, after being incident on the visible light imaging lens group, converges onto the camera target surface. This convergence is used to identify and track moving targets, determine the angle between the moving target and the line of sight of the measurement optical system, and, combined with the distance from the moving target to the measurement optical system, determine the target's position in two-dimensional space. The visible light collimating lens group redirects the visible light path to be parallel to the optical axis and positions it in a second layer above the optical axis. This design separates the visible light path from the laser and mid-wave infrared paths in space, avoiding mutual interference. The visible light imaging lens group focuses the visible light path onto the camera target surface. The camera can analyze the image content in real time, identify and track moving targets, and determine the angle between the moving target and the line of sight of the measurement optical system by analyzing the target's position and size in the image. Combined with the distance from the moving target to the measurement optical system measured by the laser rangefinder receiving correction lens group, the camera can calculate the target's position in two-dimensional space. .

[0063] The mid-infrared light path transmitted through secondary mirror 2 of the Cassegrain lens group is deflected and becomes parallel to the optical axis, located in the second layer above the optical axis. This second-layer mid-infrared light path, after being incident on the mid-infrared projection lens group, is imaged onto the thermal imager target surface, used to capture and track the target and determine the temperature distribution of moving targets. The mid-infrared projection lens group images the mid-infrared light path, ultimately projecting the image onto the thermal imager target surface. Using image processing algorithms, the thermal imager can analyze the image content in real time to identify and track moving targets. Different colors in the infrared thermal image represent different temperatures of the measured object; by analyzing the color distribution of the target in the image, the thermal imager can determine the temperature distribution of the moving target.

[0064] The working principle of the above-mentioned optical system for measuring moving targets is as follows:

[0065] (1) Distance measurement:

[0066] The laser emitter emits a laser beam that illuminates the moving target. The reflected laser beam passes through the Cassegrain lens group and the spectral beam splitter 3 before entering the laser ranging receiver correction lens group. The laser ranging receiver correction lens group focuses the laser beam onto the detector target surface, and the detector calculates the distance from the moving target to the measuring optical system based on the received laser signal.

[0067] (2) Two-dimensional spatial location recognition and tracking:

[0068] Visible light emitted from a visible light source (such as sunlight or artificial light) illuminates a moving target. The reflected visible light passes through the Cassegrain lens group and the spectral beam splitter 3 before entering the visible light collimating lens group and the visible light imaging lens group. The visible light imaging lens group focuses the visible light onto the camera target surface. The camera identifies and tracks the moving target based on the received visible light image. Combined with the distance from the moving target to the measuring optical system measured by the laser rangefinder receiving and correction lens group, the target's position in two-dimensional space can be calculated.

[0069] (3) Determination of temperature distribution:

[0070] Mid-wave infrared radiation emitted by a moving target is transmitted through a Cassegrain lens group and then incident on a mid-wave infrared projection lens group. The projection lens group images the mid-wave infrared radiation onto the target surface of the thermal imager. The thermal imager analyzes the image content in real time based on the received mid-wave infrared image to identify and track the moving target and determine the temperature distribution of the moving target.

[0071] Therefore, the moving target measurement optical system of this application integrates multiple technologies such as laser ranging, visible light imaging, and mid-wave infrared imaging to achieve comprehensive measurement and analysis of moving targets using a single device. It possesses advantages such as high precision, high reliability, and real-time performance, and has broad application prospects in scientific research, industry, and other fields.

[0072] like Figure 1 The image shown illustrates another embodiment of the moving target measurement optical system of this application, which may include a main optical system, a laser rangefinder receiving and correction lens group, a visible light collimating lens group, a visible light imaging lens group, and a mid-wave infrared projection lens group. This achieves an optical system where laser rangefinders and visible / infrared measurements share the same aperture.

[0073] The main optical system consists of a primary mirror 1 (concave parabolic Cassegrain lens group), a secondary mirror 2 (convex hyperboloid spectral beam splitter Cassegrain lens group), a spectral beam splitter 3, a first folded-axis reflector 4, and a second folded-axis reflector 5. For the laser ranging receiving optical path and the visible light measurement optical path, the secondary mirror 2 is a reflector; for the infrared measurement optical path, the secondary mirror 2 is a lens.

[0074] The laser rangefinder receiving and correction lens assembly consists of a planar correction plate 6, a positive optical power bending-to-image-plane lens 7, and a first positive optical power biconvex lens 8. In this embodiment, both the positive optical power bending-to-image-plane lens 7 and the first positive optical power biconvex lens 8 are H-ZF52 lenses.

[0075] The visible light collimating lens group consists of a second positive power biconvex lens 9, a first meniscus lens 10, a first negative power biconcave lens 11, a negative power cemented lens 12, a second meniscus lens 13, and a third folded-axis reflector 14. In this embodiment, the second positive power biconvex lens 9 is an H-ZF88 lens, the first meniscus lens 10 is a positive power meniscus H-LAF1 lens bent towards the parallel light path, the first negative power biconcave lens 11 is an H-ZF88 lens, the negative power cemented lens 12 is an H-LAF1 lens or an H-ZF13 lens, and the second meniscus lens 13 is a meniscus H-ZF88 lens bent towards the primary image plane.

[0076] The visible light imaging lens group consists of a third meniscus lens 15, a fourth meniscus lens 16, a third positive power biconvex lens 17, a second negative power biconcave lens 18, a fifth meniscus lens 19, and a sixth meniscus lens 20. In this embodiment, the third meniscus lens 15 is a positive power HZF6 meniscus lens with curving towards the image side, the fourth meniscus lens 16 is a negative power HLAF4 meniscus lens with curving towards the image side, the third positive power biconvex lens 17 is an HQK3 lens, the second negative power biconcave lens 18 is an HLAF4 lens, the fifth meniscus lens 19 is a positive power HQK3 meniscus lens with curving towards the image side, and the sixth meniscus lens 20 is a positive power HZF6 meniscus lens with curving towards the image side.

[0077] The mid-wave infrared projection lens group consists of a first silicon lens 21, a negative optical power biconcave germanium lens 22, a positive optical power zinc sulfide lens 23 bent towards the image plane, and a positive optical power second silicon lens 24 bent towards the image plane. In this embodiment, the first silicon lens 21 is a positive optical power silicon lens bent towards the image plane.

[0078] As an example, in this embodiment, the distance between the primary mirror 1 and the secondary mirror 2 in the primary optical system is 833.3 mm; the distance between the reflecting surface of the secondary mirror 2 and the spectral beam splitter 3 is 600 mm; the distance between the transmitting surface of the secondary mirror 2 and the first folded-axis mirror 4 is 100 mm; and the distance between the first folded-axis mirror 4 and the second folded-axis mirror 5 is 540 mm. The distance between the rear surface of the spectral beam splitter 3 and the laser ranging receiver correction lens group is 190 mm; the distance between the front surface of the spectral beam splitter 3 and the visible light collimating lens group is 240 mm; the distance between the second folded-axis mirror 5 and the mid-wave infrared projection lens group is 50 mm; and the distance between the visible light collimating lens group and the visible light imaging lens group is 90 mm.

[0079] For ease of description, the parameters of each optical device in this embodiment are explained in a table:

[0080]

[0081]

[0082]

[0083]

[0084]

[0085] For optical devices with parabolic, hyperboloid, and aspherical surface types listed in Tables 1 to 5 above, the sagitta can be calculated using the following equations:

[0086]

[0087] In the formula, Indicates the height of the arrow. Indicates curvature. r Indicates the radius of the ring. Denotes the coefficient of the quadratic term. Represents the coefficients of a fourth-order aspheric surface. Represents the 6th order aspheric coefficient. Represents the 8th order aspheric coefficient. This represents the 10th order aspheric coefficient.

[0088] Based on the above parameters, the aperture of the moving target measurement optical system is Φ450mm. The focal length of the visible light imaging system, where the camera target surface is located, is 4500mm, with an F-number of 10, suitable for a camera with a resolution of 1920×1080 and a pixel size of 10μm×10μm. The focal length of the mid-wave infrared measurement system, where the thermal imager target surface is located, is 900mm, with an F-number of 2, suitable for a cooled infrared thermal imager with a resolution of 640×512 and a pixel size of 15μm×15μm. The receiving focal length of the laser rangefinder, where the detector target surface is located, is 550mm, and the field of view is 0.64mrad×0.64mrad.

[0089] The working principle of the above embodiments is as follows:

[0090] A primary mirror 1, with a concave parabolic surface, converges light rays incident parallel to the optical axis to its focal point, which serves as the system's entrance pupil. For the visible light and laser ranging receiving optical paths, a secondary mirror 2 acts as a reflector. One focal point of the secondary mirror 2 coincides with the focal point of the primary mirror 1, converging the light rays to the other focal point of the hyperboloid, i.e., the primary image plane. A spectral beam splitter 3 is positioned in front of the primary image plane to reflect the visible light path and transmit the laser light path. The laser light path transmitted through the secondary mirror 2 is compensated for by a planar correction plate 6, which mitigates the astigmatism introduced by the spectral beam splitter 3 in the converging optical path. Then, a positive optical power bend-to-image-plane lens 7 and a first positive optical power biconvex lens 8 converge the light rays onto the detector target surface. The visible light path reflected by the spectral beam splitter 3 continues to propagate after converging to the primary image plane. The beam diverges and is collimated into a parallel beam by a visible light collimating lens group, with the aperture stop conjugated to the parallel optical path by the primary mirror 1. The parallel light is refracted by the third folding-axis reflector 14 to the second layer above the main optical system, where the optical axis is parallel to the optical axis of the primary and secondary mirrors 2. The refracted parallel beam is then converged onto the camera target surface by the visible light imaging lens group. For the mid-wave infrared light path, the secondary mirror 2 is a lens that diverges the converged light from the primary mirror 1, increasing the focal length of the primary mirror 1 and the secondary mirror 2. This allows the mid-wave infrared light path to be folded upwards towards the main optical system, and then refracted to the second layer above the main optical system by the first folding-axis reflector 4 and the second folding-axis reflector 5. After refracting, the optical axis is parallel to the optical axes of the primary mirror 1 and the secondary mirror 2. In the mid-wave infrared projection lens group, a 4-element structure is used to re-converge the diverged light rays after the primary infrared image of the primary mirror 1 and the secondary mirror 2, image them onto the thermal imager target surface, and project the entrance pupil onto the cold screen position, achieving aperture matching with the cold screen.

[0091] Based on the aforementioned optical system for measuring moving targets, this application also proposes a method for measuring moving targets, which may include:

[0092] The laser beam and visible light are respectively irradiated onto the moving target, and the reflected laser beam and visible light are incident on the primary mirror 1 of the Cassegrain lens group;

[0093] And cause the mid-wave infrared radiation emitted by the moving target to be incident on the primary mirror 1 of the Cassegrain lens group.

[0094] When performing specific measurements and calculations, you can:

[0095] The distance from the moving target to the measuring optical system is calculated based on the laser signal in the laser optical path converged by the detector target surface.

[0096] The visible light image is obtained by the visible light path converged by the camera target surface, the moving target is identified and tracked, the angle between the moving target and the line of sight of the measurement optical system is determined, and the position of the target in two-dimensional space is determined by combining the distance of the moving target to the measurement optical system.

[0097] Mid-wave infrared images are obtained by focusing the mid-wave infrared light path on the target surface of the thermal imager, capturing and tracking the target, and determining the temperature distribution of the moving target.

[0098] Further verification of the technical effects of this application is required. For example... Figure 2 The figure shows the MTF curve of a visible light imaging optical system with a spatial frequency of 50 lp / mm. Figure 3 The diagram shown is a dot plot of a visible light imaging optical system, as follows: Figure 4 The figure shows the MTF curve of a mid-wave infrared measurement optical system with a spatial frequency of 33 lp / mm. Figure 5 The image shown is a point diagram of a mid-wave infrared measurement optical system. From... Figures 2 to 5 It can be seen that the visible light imaging optical system has an MTF (Modulation Transfer Function) better than 0.35 at a spatial frequency of 50 lp / mm, and the diameter of the speckle in the dot plot is less than 0.01 mm, which is less than one pixel. The mid-wave infrared measurement optical system has an MTF (Modulation Transfer Function) better than 0.31 at a spatial frequency of 33 lp / mm, and the diameter of the speckle in the dot plot is less than 0.008 mm, which is less than one pixel. Both the visible light imaging and mid-wave infrared measurement optical systems have good imaging quality, meeting the requirements for target observation. Figure 6 The image shows the energy curve of the enclosing circle of a laser ranging and receiving optical system. Figure 6 It can be seen that 80% of the energy of the laser ranging and receiving optical system is concentrated within a radius of 6μm, which has a good degree of energy concentration and meets the requirements for receiving target ranging echoes.

[0099] The above are merely preferred embodiments of this application and are not intended to limit this application. Various modifications and variations can be made to this application by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the protection scope of this application.

Claims

1. An optical system for measuring moving targets, characterized in that, It includes the main optical system, the laser rangefinder receiver correction lens group, the visible light collimating lens group, the visible light imaging lens group, and the mid-wave infrared projection lens group; The main optical system includes a Cassegrain lens group and a spectral beam splitter (3); light rays incident parallel to the optical axis are incident through the primary mirror (1) of the Cassegrain lens group; the spectral beam splitter (3) is located in front of the primary image of the secondary mirror (2) of the Cassegrain lens group, so that the visible light path is reflected and the laser light path is transmitted. After the laser beam is incident on the laser ranging receiver correction mirror group, it converges to the detector target surface to calculate the distance from the moving target to the measuring optical system. After the visible light path is incident on the visible light collimating lens group, the visible light path is turned to be parallel to the optical axis and the visible light path is located in the second layer above the optical axis; The visible light path located in the second layer is incident on the visible light imaging lens group and converges to the camera target surface to identify and track moving targets, determine the angle between the moving target and the line of sight of the measurement optical system, and combine the distance between the moving target and the measurement optical system to determine the position of the target in two-dimensional space. The mid-wave infrared light path transmitted through the secondary mirror (2) of the Cassegrain lens group is parallel to the optical axis after being deflected and is located in the second layer above the optical axis; The mid-wave infrared light path located in the second layer is incident on the mid-wave infrared projection lens group and imaged on the target surface of the thermal imager, which is used to capture and track the target and determine the temperature distribution of the moving target.

2. The moving target measurement optical system according to claim 1, characterized in that, The main optical system also includes a first folding-axis mirror (4) and a second folding-axis mirror (5); The mid-wave infrared light path transmitted through the secondary mirror (2) of the Cassegrain mirror group is parallel to the optical axis after being turned by the first folded-axis mirror (4) and the second folded-axis mirror (5).

3. The moving target measurement optical system according to claim 2, characterized in that, The laser ranging receiver correction lens group includes a planar correction plate (6), a positive optical power bending image plane lens (7), and a first positive optical power biconvex lens (8) arranged sequentially along the laser optical path; the laser optical path compensates for the astigmatism introduced by the spectral beam splitter (3) through the planar correction plate (6), and then converges sequentially through the positive optical power bending image plane lens (7) and the positive optical power biconvex lens.

4. The moving target measurement optical system according to claim 3, characterized in that, The visible light collimating lens group includes a second positive power biconvex lens (9), a first meniscus lens (10), a first negative power biconcave lens (11), a negative power cemented lens (12), a second meniscus lens (13), and a third folded-axis reflector (14) arranged sequentially along the visible light path. The first meniscus lens (10) is a meniscus lens with positive optical power that bends toward the parallel optical path, and the second meniscus lens (13) is a meniscus lens that bends toward the primary image plane.

5. The moving target measurement optical system according to claim 4, characterized in that, The visible light imaging lens group includes a third meniscus lens (15), a fourth meniscus lens (16), a third positive power biconvex lens (17), a second negative power biconcave lens (18), a fifth meniscus lens (19), and a sixth meniscus lens (20) arranged sequentially along the visible light path located in the second layer. The third meniscus lens (15) is a positive power meniscus lens bent towards the image side, the fourth meniscus lens (16) is a negative power meniscus lens bent towards the image side, the fifth meniscus lens (19) is a positive power meniscus lens bent towards the image side, and the sixth meniscus lens (20) is a positive power meniscus lens bent towards the image side.

6. The moving target measurement optical system according to claim 5, characterized in that, The mid-wave infrared projection lens group includes a first silicon lens (21), a negative optical power biconcave germanium lens (22), a positive optical power zinc sulfide lens (23) bent toward the image plane, and a second silicon lens (24) bent toward the image plane, arranged sequentially along the mid-wave infrared optical path located in the second layer.

7. The moving target measurement optical system according to claim 6, characterized in that, The primary mirror (1) of the Cassegrain lens group is a concave parabolic mirror, the secondary mirror (2) of the Cassegrain lens group is a convex hyperboloid spectral splitter (2), and at least one of the first positive power biconvex lens (8), the fourth meniscus lens (16) and the second negative power biconcave lens (18) has an aspherical surface. Methods for calculating the sag of parabolic, hyperboloid, and aspherical surfaces include: in, Indicates the height of the arrow. Indicates curvature. r Indicates the radius of the ring. Denotes the coefficient of the quadratic term. Represents the coefficients of a fourth-order aspheric surface. Represents the 6th order aspheric coefficient. Represents the 8th order aspheric coefficient. This represents the 10th order aspheric coefficient.

8. The moving target measurement optical system according to claim 7, characterized in that, The focal length of the visible light imaging system on which the camera target is located is 4500mm and the F number is 10. The focal length of the mid-wave infrared measurement system on which the thermal imager target surface is located is 900mm, and the F-number is 2. The receiving focal length of the laser rangefinder on which the detector target is located is 550mm.

9. A method for measuring a moving target, based on the moving target measuring optical system according to any one of claims 1 to 8, characterized in that, include: The laser beam and visible light are respectively irradiated onto the moving target, and the reflected laser and visible light are incident on the primary mirror of the Cassegrain lens group (1); And cause the mid-wave infrared radiation emitted by the moving target to be incident on the primary mirror of the Cassegrain lens group (1).

10. The moving target measurement method according to claim 9, characterized in that, Also includes: The distance from the moving target to the measuring optical system is calculated based on the laser signal in the laser optical path converged by the detector target surface. The visible light image is obtained by the visible light path converged by the camera target surface, the moving target is identified and tracked, the angle between the moving target and the line of sight of the measurement optical system is determined, and the position of the target in two-dimensional space is determined by combining the distance of the moving target to the measurement optical system. Mid-wave infrared images are obtained by focusing the mid-wave infrared light path on the target surface of the thermal imager, capturing and tracking the target, and determining the temperature distribution of the moving target.

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