Satellite-borne omnidirectional staring imaging system and method

Abstract

The invention relates to a satellite-borne omnidirectional staring imaging system and a satellite-borne omnidirectional staring imaging method, which are used for monitoring a space target. The system comprises a long-wave infrared panoramic annulus optical system, an electric intelligent light shield, an annular heterogeneous long-wave infrared detector and a rear-end signal processing circuit. The optical system adopts a low-temperature athermalization design, and combines with an electric light shield to dynamically suppress stray light, so that earth limb panoramic view field detection is realized. The annular detector is matched with a panoramic field of view, the optical design is simplified, the large-field-of-view imaging performance is improved, and time domain seamlessness and space domain blindness are ensured. The rear-end signal processing circuit is composed of an FPGA, a DSP, a CPU, an NPU and the like, and real-time space situation awareness and load on-orbit self-adaptive adjustment are achieved. According to the system, omnidirectional coverage of space target detection is realized, and the monitoring efficiency is improved.

Description

Technical Field

[0001] The present invention relates to the field of optical remote sensing technology, and in particular to a satellite-borne omnidirectional staring imaging system and method. Background Art

[0002] Optical imaging systems are widely used for target detection and tracking, among which infrared detection systems complete target detection and tracking based on the difference between the heat energy radiated or reflected by the object and the background energy. Infrared detection systems are now widely used in night vision, detection, tracking, search and rescue, non-destructive evaluation, gas analysis and condition monitoring and other fields.

[0003] When space targets are in orbit, they will emit thermal radiation into space while reflecting the radiation from the sun and the earth. Due to their low temperature, the energy of spontaneous radiation is mainly concentrated in the long-wave infrared band. Satellites need to use long-wave infrared detection systems to monitor space targets. However, in order to achieve omnidirectional monitoring of space targets near the edge of the earth, existing satellite-borne monitoring systems usually rely on complex mechanical rotating imaging components. This detection method is not only unable to monitor wide-area space targets in real time, but also difficult to achieve accurate positioning of space targets. Summary of the invention

[0004] The present invention aims to provide a satellite-borne omnidirectional staring imaging system and method to solve the problem that the existing detection methods are not only unable to monitor wide-area space targets in real time, but also difficult to achieve accurate positioning of space targets.

[0005] To achieve the above-mentioned purpose, the present invention provides the following technical solutions: a satellite-borne omnidirectional staring imaging system, comprising a long-wave infrared panoramic annular optical system, an electric intelligent sunshade, an annular heterogeneous long-wave infrared detector and a back-end signal processing circuit; the long-wave infrared panoramic annular optical system can obtain a panoramic field of view of the earth's limb centered on the satellite; the electric intelligent sunshade can dynamically suppress stray light; the annular heterogeneous long-wave infrared detector has an annular pixel layout matching the panoramic annular field of view, and can receive and image long-wave infrared radiation; the back-end signal processing circuit includes FPGA, DSP, CPU, and NPU chips, which can extract the position information and trajectory information of space targets in the panoramic image in real time, and control the electric intelligent sunshade to achieve on-orbit fine-tuning of the shading angle.

[0006] Specifically, the long-wave infrared panoramic annular optical system includes a panoramic surround reflector system and a refracting rear optical path; the panoramic surround reflector system can receive the long-wave infrared radiation of space targets in the annular field of view at the earth's limb, and reflect it to the refracting rear optical path; the refracting rear optical path has a zoom feature, which changes the total optical focal length of the entire optical system by changing the interval between lens groups, and uses a compensating optical group to compensate for image plane drift to maintain good imaging quality and contrast.

[0007] Specifically, the long-wave infrared panoramic annular optical system adopts low-temperature optics for athermal design, and realizes ultra-lightweight optomechanical structure self-compensation athermal performance through optical + structural composite passive athermal design combined with modular topological optimization design method through optomechanical material matching design and additive manufacturing technology.

[0008] Specifically, the electric intelligent sunshade utilizes a parallel electric push rod array in combination with a back-end information processing circuit to realize the expansion and folding of the upper and lower circles of the foldable sunshade, so as to achieve on-track fine-tuning of the shading angle.

[0009] Specifically, the annular heterogeneous long-wave infrared detector focal plane array has high dynamic range performance, can cope with weak target detection under strong background radiation, and adopts a high-speed and low-noise readout circuit design to support high-speed data acquisition to complete real-time perception of space situation.

[0010] Specifically, the workflow of the back-end signal processing circuit includes: Step 1: FPGA performs analog-to-digital conversion, data packaging, caching and simple preprocessing on the analog signal output by the annular heterogeneous long-wave infrared detector; Step 2: The pre-processed data is sent to the DSP and NPU, where the DSP is responsible for complex signal processing tasks such as FFT, convolution and filtering, and the NPU is responsible for advanced pattern recognition or classification, such as object detection and recognition in images; Step 3: Finally, the processed data is transmitted to the external system through the communication interface or output device for real-time feedback control.

[0011] A spaceborne omnidirectional staring imaging method comprises the following steps: Step 1: Use the long-wave infrared panoramic annular optical system to receive the long-wave infrared radiation of space targets in the panoramic field of view of the earth's limb centered on the satellite, and image it onto the annular heterogeneous long-wave infrared detector; Step 2: Preliminarily extract the position information and trajectory information of the spatial target in the panoramic image through the back-end signal processing circuit; Step 3: Adjust the focal length of the optical system to further improve the signal-to-noise ratio and position information accuracy of the target.

[0012] Specifically, the long-wave infrared panoramic annular optical system achieves dynamic stray light suppression through an electric intelligent sunshade.

[0013] Specifically, the back-end signal processing circuit outputs a trigger signal to control the electric intelligent sunshade to achieve on-track fine-tuning of the shading angle according to changes in the on-track posture information of the camera.

[0014] The principle and beneficial effects of this technical solution: (1) The satellite-borne omnidirectional staring imaging system does not require a complex mechanical scanning structure and can monitor high-speed moving space targets in the panoramic field of view of the Earth's limb in real time.

[0015] (2) The long-wave infrared annular heterogeneous detector used in the satellite-borne omnidirectional staring imaging system has an annular pixel layout that matches the panoramic annular field of view. Compared with the traditional detector photosensitive pixel layout, this structure simplifies the optical system design and improves the imaging performance under the panoramic field of view, thus achieving seamless time domain and blind space in the spatial domain for space surveillance.

[0016] (3) The satellite-borne omnidirectional staring imaging system can operate in low-Earth orbit, which requires only a smaller optical system to achieve the same detection effect as in geosynchronous orbit, thereby significantly reducing the size and cost of the satellite. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 An exemplary operation diagram of a spaceborne omnidirectional staring imaging system for space target detection is provided; Figure 2 Schematic diagram of a long-wave infrared panoramic annular optical system of an embodiment; Figure 3 A mapping diagram of a panoramic annular infrared optical system and a long-wave infrared annular heterogeneous focal plane array of an embodiment; Figure 4 This is a working diagram of the electrically controlled intelligent sunshade of the embodiment; Figure 5 is a hardware architecture diagram of a back-end signal processing circuit of an embodiment; In the figure: 1. Satellite-borne omnidirectional staring imaging system; 2. Space target; 3. Annular field of view; 4. Free-form surface reflector; 5. Front fixed group; 6. Zoom group; 7. Fixed group; 8. Compensation group; 9. Annular heterogeneous long-wave infrared detector; 10. Upper circle of sunshade; 11. Lower circle of sunshade; 12. Parallel electric push rod array; 13. Sun interrupter; 14. Interrupter along the annular slide rail; 15. Sunlight; 16. Rear optical path. DETAILED DESCRIPTION

[0018] The present invention is further described in detail below in conjunction with the accompanying drawings and embodiments: Example

[0019] like Figure 1As shown, an example of the application of the satellite-borne omnidirectional staring imaging system 1 in the detection of a space target 2 is shown. In this embodiment, the system has a 360° annular field of view 3 to observe the annular region of space above the surface of the earth. Once the space target 2 appears in the annular field of view 3, the satellite-borne omnidirectional staring imaging system 1 can detect the long-wave infrared radiation of the space target 2, and then display it on a display device, an alarm system or any device of a launch detection system. By combining the target detection and tracking algorithm, the system can extract the position information and trajectory information of the space target 2 in real time.

[0020] like Figure 2 The long-wave infrared panoramic annular optical system shown in the figure comprises a free-form surface reflector 4 and a refractive rear optical path 16 composed of a front fixed group 5, a zoom group 6, a fixed group 7 and a compensation group 8. The long-wave infrared panoramic annular optical system is an optical system with a large field of view, a large aperture, a small F number, a wide spectrum and variable focus. Spherical aberration, off-axis aberration and chromatic aberration have a great influence on the imaging quality of the optical system. The system uses a variety of materials such as germanium, zinc selenide and chalcogenide glass to correct the system chromatic aberration, and uses free-form surface and high-order aspheric surface technology to correct the system aberration. Through the reasonable distribution of optical power of a variety of materials and the control of lens curvature, a long-wave infrared panoramic annular optical system with a large field of view, a large aperture, a small F number, a wide spectrum and variable focus under non-thermal conditions is realized.

[0021] The three-dimensional panoramic field of view of the earth's limb airspace is reflected by the free-form surface reflector 4 to obtain a ring-shaped outgoing infrared radiation beam with a smaller aperture and refraction angle. The long-wave infrared radiation is then propagated through multiple lens groups of the refractive rear optical path 16 and is finally mapped onto the focal plane array of the annular heterogeneous long-wave infrared detector 9. In order to avoid energy outside the field of view, a Rio diaphragm can be used in some embodiments. The Rio diaphragm is located at the exit pupil, which can reduce the background radiation of the system structure and reduce stray light.

[0022] The long-wave infrared panoramic annular optical system is a zoom optical system. The total optical power of the entire optical system can be changed by changing the interval between the lens groups, and the relative aperture is kept basically unchanged during the zoom process, so that the imaging height remains unchanged and the imaging quality is clear. The optical system uses a moving compensation optical group to compensate for image drift.

[0023] The long-wave infrared panoramic annular optical system has athermal infrared optomechanical performance in ultra-low temperature working environment, and can adapt to the interference of external heat flow changes on satellite platforms. The optical-structural composite passive athermal design is adopted, combined with the modular topological optimization design method, and the ultra-lightweight optomechanical structure self-compensation athermal performance is realized through the optomechanical material matching design and additive manufacturing technology. In terms of optics, the focal length of each lens is optimized and distributed, so that the defocus generated by the optical element and the defocus generated by the mechanical structure compensate each other to achieve the stability of the focal plane when the temperature changes; in terms of structure, the lightweight optomechanical structure design is mainly carried out based on the modular topological optimization design method, and the optomechanical structure topological optimization design is carried out in combination with multi-parameter and multi-objective control constraints of precision control, stiffness control, and strength control. The topological optimization design structure is carried out through 3D printing additive manufacturing to carry out parts manufacturing, avoiding the restrictions of traditional material processing technology on the topological optimization structure configuration, and realizing ultra-lightweight structure design. Through the intelligent temperature control of the core optical components, the corresponding relationship between image quality and temperature is analyzed, and an intelligent temperature control adaptive model of the image plane and temperature is established, and the active self-compensation capability of the image plane is realized through the model.

[0024] like Figure 3 As shown, mapping of the limb omnidirectional annular field of view 3 to a long-wave infrared annular heterogeneous focal plane array is demonstrated. Figure 3 The long-wave infrared annular heterogeneous detector shown in A has the characteristics of adaptive pixel layout, which can match the annular field of view of the panoramic annular infrared optical imaging system 3. In addition, the detector has high dynamic range performance, which can cope with the detection of weak targets under strong background radiation, and adopts high-speed and low-noise readout circuit design to support high-speed data acquisition, which can complete the real-time perception of space situation. Figure 3 The upper field of view of the edge annular space shown in B is mapped to Figure 3 The outer ring of the annular heterogeneous focal plane shown in A, with the lower field of view mapped to Figure 3 Inner ring of the annular isomeric focal plane shown in A. Figure 3 Figure C shows the imaging field of view of the long-wave infrared panoramic annular optical system after zooming in a certain embodiment. At this time, the zoom ratio is 2 times, the resolution is doubled, and the imaging field of view is Figure 3 The middle shaded area of ​​the annular field of view 3 shown in C.

[0025] like Figure 4The working mode of the electrically controlled intelligent sunshade shown in the figure is that the upper circle 10 of the sunshade, the lower circle 11 of the sunshade and the parallel electric push rod array 12 are connected, and are controlled by the back-end information processing circuit of the camera to realize the expansion and folding of the upper and lower circles of the foldable sunshade. In the fairing before the camera is launched, the control signal drives the parallel electric push rod array 12 to fold, so that the entire camera shrinks to the minimum volume; when the camera is deployed in orbit, the parallel electric push rod receives the expansion signal of the back-end information processing circuit, quickly and accurately expands the sunshade into place, and can output a control signal to realize the on-orbit fine adjustment of the shading angle according to the change of the camera's posture information on the orbit.

[0026] The solar shield 13 of the electrically controlled intelligent sunshade can obtain the azimuth of the midnight sun on the horizon from the back-end information processing circuit online in real time, and control the solar shield 13 to move accurately to the solar azimuth along the annular slide rail 14, and automatically unfold the shielding plate to shield the sunlight 15, so as to prevent the midnight sun 15 from directly shining on the detector and causing damage to the detector. In the case of non-direct midnight sun 15, the intelligent shielding plate is retracted under the control of the back-end information processing circuit, which does not affect the observation of the earth.

[0027] like Figure 5 As shown, the hardware architecture of the back-end signal processing circuit, the hardware deployment of the back-end signal processing circuit adopts the architecture of FPGA+DSP+CPU+NPU to realize the hardware design of the high-performance processing platform to meet the needs of real-time detection and tracking of space target 2 by the space-based panoramic ring optical imaging system, and control the electric intelligent sunshade to achieve on-orbit fine-tuning of the sunshade angle.

[0028] The workflow of the back-end signal processing circuit can be described as follows: the CPU is responsible for the coordination of the entire system, managing the communication between chips, task scheduling, and low-speed data processing. First, the FPGA performs analog-to-digital conversion, data packaging, caching, and other simple preprocessing on the analog signal output by the annular heterogeneous long-wave infrared detector 9; then when a frame buffer is full, the preprocessed data is transmitted to the DSP and NPU. Among them, the DSP is responsible for complex signal processing tasks, such as FFT, convolution, and filtering. The processed data can be passed to the CPU for further processing or to the NPU for reasoning; the NPU is responsible for high-level pattern recognition or classification of the data, such as target detection and recognition in the image. Finally, the processed data is transmitted to the external system through the communication interface or output device, or used for real-time feedback control. The above data flow and communication mechanism can flexibly realize the orderly execution of multiple devices and multiple tasks, reduce the CPU processing time consumed by communication between devices, and avoid conflicts caused by bus resource competition. In addition, the architecture of the combination of FPGA, DSP, CPU, and NPU can be flexibly expanded according to the application scenario to process different types of signals and realize intelligent monitoring of space targets 2 in complex scenarios.

[0029] Although the specific embodiments and aspects of the present disclosure have been illustrated and described herein, various other changes and modifications may be made without departing from the scope of the present disclosure. In addition, although various aspects are described herein, these aspects do not have to be used in combination. Therefore, the attached claims are intended to cover all such changes and modifications within the scope of the embodiments of the present disclosure.

[0030] It should now be understood that the embodiments of the present disclosure include infrared detection systems, methods, and non-transitory computer readable media for space target 2 detection, and these infrared detection systems have a 360-degree panoramic field of view. It should also be understood that these embodiments are only examples and are not intended to limit the scope of the present disclosure.

[0031] The above is only an embodiment of the present invention, and the common knowledge such as the known specific technical solutions or characteristics in the solution is not described in detail here. For those skilled in the art, without departing from the technical solution of the present invention, several modifications and improvements can be made, which should also be regarded as the protection scope of the present invention, and these will not affect the effect of the implementation of the present invention and the practicality of the patent. The scope of protection required by this application shall be based on the content of its claims, and the specific implementation methods and other records in the specification can be used to interpret the content of the claims.

Claims

1. A satellite-borne omnidirectional staring imaging system, characterized in that: It includes a long-wave infrared panoramic annular optical system, an electric intelligent sunshade, an annular heterogeneous long-wave infrared detector and a back-end signal processing circuit; the long-wave infrared panoramic annular optical system can obtain a panoramic field of view of the earth's limb centered on the satellite; the electric intelligent sunshade can dynamically suppress stray light; the annular heterogeneous long-wave infrared detector has an annular pixel layout matching the panoramic annular field of view, and can receive and image long-wave infrared radiation; the back-end signal processing circuit includes FPGA, DSP, CPU, and NPU chips, which can extract the position information and trajectory information of space targets in the panoramic image in real time, and control the electric intelligent sunshade to achieve on-orbit fine-tuning of the shading angle.

2. The satellite-borne omnidirectional staring imaging system according to claim 1, characterized in that: The long-wave infrared panoramic annular optical system comprises a panoramic surround reflector system and a refracting diffractive rear optical path; the panoramic surround reflector system can receive the long-wave infrared radiation of space targets in the annular field of view at the earth's limb and reflect it to the refracting diffractive rear optical path; the refracting diffractive rear optical path has a zoom feature, which changes the total optical focal length of the entire optical system by changing the interval between lens groups, and adopts a compensating optical group to compensate for image plane drift, so as to maintain good imaging quality and contrast.

3. The satellite-borne omnidirectional staring imaging system according to claim 2, characterized in that: The long-wave infrared panoramic annular optical system adopts low-temperature optics for athermal design, and realizes ultra-lightweight optomechanical structure self-compensation athermal performance through optical-structural composite passive athermal design combined with modular topological optimization design method through optomechanical material matching design and additive manufacturing technology.

4. The satellite-borne omnidirectional staring imaging system according to claim 1, characterized in that: The electric intelligent sunshade utilizes a parallel electric push rod array in combination with a back-end information processing circuit to realize the expansion and folding of the upper and lower circles of the foldable sunshade, so as to achieve on-track fine adjustment of the shading angle.

5. The satellite-borne omnidirectional staring imaging system according to claim 1, characterized in that: The annular heterogeneous long-wave infrared detector focal plane array has high dynamic range performance, can cope with weak target detection under strong background radiation, and adopts high-speed low-noise readout circuit design to support high-speed data acquisition to complete real-time perception of space situation.

6. The satellite-borne omnidirectional staring imaging system according to claim 1, characterized in that: The workflow of the back-end signal processing circuit includes: Step 1: FPGA performs analog-to-digital conversion, data packaging, caching and simple preprocessing on the analog signal output by the annular heterogeneous long-wave infrared detector; Step 2: The pre-processed data is transmitted to the DSP and NPU, where the DSP is responsible for complex signal processing tasks and the NPU is responsible for advanced pattern recognition or classification; Step 3: Finally, the processed data is transmitted to the external system through the communication interface or output device for real-time feedback control.

7. A method for using the spaceborne omnidirectional staring imaging system according to claim 1, characterized in that: The following steps are involved: Step 1: Use the long-wave infrared panoramic annular optical system to receive the long-wave infrared radiation of space targets in the panoramic field of view of the earth's limb centered on the satellite, and image it onto the annular heterogeneous long-wave infrared detector; Step 2: Preliminarily extract the position information and trajectory information of the spatial target in the panoramic image through the back-end signal processing circuit; Step 3: Adjust the focal length of the optical system to further improve the signal-to-noise ratio and position information accuracy of the target.

8. The method for using the spaceborne omnidirectional staring imaging system according to claim 7, characterized in that: The long-wave infrared panoramic annular optical system achieves dynamic stray light suppression through an electric intelligent sunshade.

9. The method for using the spaceborne omnidirectional staring imaging system according to claim 8, characterized in that: The back-end signal processing circuit outputs a trigger signal to control the electric intelligent sunshade to achieve on-track fine adjustment of the shading angle according to the change of the on-track posture information of the camera.

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