Computational optical imaging systems and methods for space situational awareness

Abstract

The application discloses a computing optical imaging system and method for space situation awareness, and relates to the technical field of optical imaging. The system comprises an optical imaging lens group, a micro-displacement driving mechanism, a focal plane detector, a time sequence control unit, an on-satellite preprocessing module and a ground image reconstruction module. The terminal lens is pushed by the micro-displacement driving mechanism to generate sub-pixel level displacement in a two-dimensional plane; the focal plane detector receives optical signals and outputs multiple frames of images according to a preset frame period; the time sequence control unit generates a synchronous signal to obtain a sequence of sub-pixel displacement images; the on-satellite preprocessing module transmits data after completing blind element compensation, multi-point correction and format conversion; and the ground image reconstruction module fuses and reconstructs the multiple frames of images to output a high-resolution image for situation awareness.

Description

Technical Field

[0001] This invention relates to the field of optical imaging technology, and more particularly to a computational optical imaging system and method for spatial situational awareness. Background Technology

[0002] Currently, with the increasing density of space activities in low Earth orbit and geostationary orbit, the number of space debris, failed satellites, and unknown small targets has surged. Space situational awareness has become the core support for the safety protection and orbit control of spacecraft in orbit. Space-based optoelectronic imaging cameras are key equipment for achieving routine monitoring because they are free from atmospheric interference and can conduct continuous observation across the entire domain.

[0003] Traditional optoelectronic imaging systems rely on fixed optical paths and detectors for single-frame imaging, making imaging performance entirely dependent on the hardware's own capabilities. This results in several intractable technical shortcomings for on-orbit applications. Deep-space targets with faint echo signals are extremely weak, and single-frame imaging cannot accumulate and enhance these signals. Furthermore, the superimposed starlight and detector noise lead to a very low signal-to-noise ratio, making faint targets easily obscured by noise, resulting in missed detections and identification failures. System resolution is solely determined by lens aperture and detector pixel specifications. Improving resolution with larger aperture lenses or high-pixel detectors significantly increases equipment size, weight, and launch costs, while also creating pressure on onboard storage, transmission, and power consumption. Hardware upgrades are significantly limited by satellite platform resources. Traditional imaging lacks subpixel multi-sampling mechanisms, resulting in the permanent loss of target details between pixels. Ordinary interpolation can only fill grayscale, failing to restore high-frequency contours, leading to blurred image edges and noticeable artifacts, which is detrimental to target orbit calculations. Attribute recognition; the system's fixed sampling frame rate cannot adapt to on-orbit targets with different speeds. High sampling for low-speed targets wastes resources, while low sampling for high-speed targets easily produces motion blur, making it difficult to balance imaging quality and on-board hardware consumption; on-board systems can only perform basic image correction, lacking denoising and detail reconstruction algorithms adapted to low signal-to-noise ratio multi-frame images; ground-based systems lack multi-frame sub-pixel fusion methods, and single-frame denoising easily loses effective target signals, resulting in insufficient imaging stability under complex starry skies; existing micro-scanning schemes involve translating the entire optical path or beam splitting prisms, resulting in bulky structures and difficulty in correcting optical path distortion; a few lens micro-motion schemes cannot achieve accurate two-dimensional four-way sub-pixel synchronous sampling, leading to large registration deviations in multi-frame images, poor super-resolution reconstruction effects, and failing to meet the miniaturization and low power consumption requirements of space-based cameras. Existing imaging systems cannot simultaneously achieve the four core requirements of high-sensitivity detection of faint targets, high-resolution imaging of small targets, lightweight equipment adaptation, and adaptive acquisition of dynamic targets, thus restricting the detection efficiency and recognition reliability of missions such as space debris monitoring, on-orbit satellite inspection, and deep space target early warning. Summary of the Invention

[0004] In view of this, embodiments of the present invention provide a computational optical imaging system and method for space situational awareness. The end lens is driven by a micro-displacement driving mechanism to generate sub-pixel-level displacement in a two-dimensional plane; the focal plane detector receives optical signals and outputs multiple frames of images according to a preset frame period; the timing control unit generates a synchronization signal to obtain a sub-pixel displacement image sequence; the on-board preprocessing module completes blind pixel compensation, multi-point correction and format conversion before transmitting data; the ground image reconstruction module fuses and reconstructs the multiple frames of images and outputs a high-resolution image for situational awareness.

[0005] This invention provides a computational optical imaging system for space situational awareness. The system includes: an optical imaging lens group, a micro-displacement driving mechanism, a focal plane detector, a timing control unit, an on-board preprocessing module, and a ground image reconstruction module. The optical imaging lens group comprises imaging lenses arranged sequentially along the optical path, each having an end lens located closest to the image plane. This end lens is used to converge the target beam to the image plane. The micro-displacement driving mechanism drives the end lens to generate sub-pixel-level displacement in a two-dimensional plane perpendicular to the optical axis, responding to a driving voltage or driving current to produce corresponding physical deformation, thereby driving the end lens to achieve minute displacements smaller than the detector pixel size in both the horizontal and vertical directions. The system comprises: a focal plane detector, which receives light signals transmitted through the end lens and converts them into electrical signals, and outputs multiple frames of images according to a preset frame period; a timing control unit, which generates synchronization timing control signals to obtain a sequence of multiple low-resolution images; an on-board preprocessing module, which receives the sequence of multiple low-resolution images, performs blind pixel compensation, multi-point correction, and data format conversion on the image sequence to generate preprocessed image data, and transmits the preprocessed image data to the ground processing end through a satellite-to-ground data transmission link; and a ground image reconstruction module, which receives the preprocessed image data and performs multi-frame fusion reconstruction processing on the sequence of multiple low-resolution images with sub-pixel displacement differences.

[0006] This application also provides a computational optical imaging method for space situational awareness. The method includes: an optical imaging lens group, comprising imaging lenses arranged sequentially along the optical path, the imaging lens group having an end lens located closest to the image plane, the end lens being used to converge a target beam to the image plane; driving the end lens to generate sub-pixel-level displacement in a two-dimensional plane perpendicular to the optical axis, generating corresponding physical deformation in response to driving voltage or driving current, thereby driving the end lens to achieve minute displacements smaller than the detector pixel size in both the horizontal and vertical directions; receiving optical signals transmitted through the end lens and converting them into electrical signals, and outputting multiple frames of images according to a preset frame period; generating a synchronization timing control signal to obtain a sequence of multiple low-resolution images; receiving the sequence of multiple low-resolution images, and performing blind pixel compensation, multi-point correction, and data format conversion on the image sequence to generate preprocessed image data, and transmitting the preprocessed image data down to a ground processing end via a satellite-to-ground data transmission link; receiving the preprocessed image data, and performing multi-frame fusion reconstruction processing on the sequence of multiple low-resolution images with sub-pixel displacement differences.

[0007] The beneficial effects of the technical solutions provided in the embodiments of the present invention include at least the following: By employing a hardware-software co-imaging architecture that combines two-dimensional subpixel micro-scanning with multi-frame computational reconstruction using the end lens, imaging resolution can be improved without increasing the optical aperture or carrying high-specification detectors, significantly reducing satellite payload weight, launch costs, and onboard storage and transmission power consumption. Relying on a multi-frame subpixel image accumulation mechanism to continuously superimpose faint echo signals from dim targets, combined with onboard blind pixel compensation, dark level and gain non-uniformity correction, and ground-side noise reduction processing, stray starlight, detector readout noise, and thermal noise are effectively suppressed, significantly improving the image signal-to-noise ratio and solving the problem of missing detections of deep-space debris and distant, faulty satellites due to noise. The timing unit achieves precise synchronization between lens displacement and detector exposure, strictly ensuring that subpixel offset is regular and controllable for each frame, avoiding image blurring caused by optical path jitter. It can also dynamically adjust the sampling frequency according to the target's motion state; low-frequency sampling for low-speed targets saves hardware resources, while high-frequency sampling for high-speed targets eliminates motion blur, balancing imaging clarity with onboard computing power and power consumption. The ground module uses curvature-like interpolation to distinguish image edges from smooth areas, adaptively preserving sharp target contours. Lateral suppression filtering removes false details and enhances effective high-frequency textures. The fused reconstructed image exhibits no obvious jagged edges or blurry artifacts, clearly showing the structural features of small targets. This enables high-precision orbit calculation and target attribute recognition. The entire micro-scanning mechanism is driven by piezoelectric ceramics or voice coil motors, featuring a compact structure and low distortion correction difficulty. It adapts to the miniaturization and low-power platform requirements of space-based cameras, comprehensively improving the detection stability and recognition reliability of space debris monitoring, on-orbit satellite inspection, and early warning of unknown deep-space targets. Attached Figure Description

[0008] Figure 1 A schematic diagram of the structure of a computational optical imaging system for spatial situational awareness provided in an embodiment of this application; Figure 2 A diagram showing the lens vibration structure of a computational optical imaging system for spatial situational awareness provided in an embodiment of this application; Figure 3 A subpixel sampling schematic diagram of a computational optical imaging system for spatial situational awareness provided in an embodiment of this application; Figure 4 A schematic diagram of the 2×2 micro-scanning imaging principle of a computational optical imaging system for spatial situational awareness provided in an embodiment of this application; Figure 5 A schematic diagram of camera information acquisition for a computational optical imaging system for spatial situational awareness provided in an embodiment of this application; Figure 6 A computational optical imaging flowchart of a computational optical imaging system for space situational awareness provided in an embodiment of this application; Figure 7 A flowchart of a computational optical imaging method for spatial situational awareness provided in an embodiment of this application. Detailed Implementation

[0009] To better understand the above technical solutions, the following will provide a detailed explanation of the technical solutions in conjunction with the accompanying drawings and specific implementation methods.

[0010] like Figure 1 The diagram shown is a structural schematic of a computational optical imaging system for space situational awareness provided in an embodiment of this application. The computational optical imaging system for space situational awareness provided in an embodiment of this application includes: an optical imaging lens group, a micro-displacement driving mechanism, a focal plane detector, a timing control unit, an on-board preprocessing module, and a ground image reconstruction module.

[0011] The optical imaging lens group includes imaging lens groups arranged sequentially along the optical path, and the imaging lens group has an end lens located closest to the image plane, the end lens being used to converge the target beam to the image plane.

[0012] The micro-displacement driving mechanism is fixedly connected to the end lens and is used to drive the end lens to generate sub-pixel-level displacement in a two-dimensional plane perpendicular to the optical axis. It generates corresponding physical deformation in response to driving voltage or driving current, thereby driving the end lens to achieve micro-displacements smaller than the detector pixel size in the horizontal and vertical directions, respectively.

[0013] It should be explained that the specific process for achieving minute displacements smaller than the detector pixel size in both the horizontal and vertical directions by pushing the end lens is as follows: The micro-displacement driving mechanism includes a piezoelectric ceramic driver or a voice coil motor; The timing control unit has a built-in complex programmable logic device, which generates an initial sub-pixel level displacement control signal according to a preset micro-scanning timing logic. The initial subpixel-level displacement control signal is amplified by a voltage amplification circuit or a current amplification circuit connected to the output terminal of the complex programmable logic device, and converted into a driving voltage signal or a driving current signal that drives the micro-displacement driving mechanism to produce physical deformation. The driving voltage signal or driving current signal is applied to the piezoelectric ceramic body or voice coil motor coil of the micro-displacement driving mechanism. The piezoelectric ceramic body, based on the inverse piezoelectric effect, responds to the changes in amplitude and polarity of the driving voltage signal and generates mechanical deformation in a corresponding direction and with a corresponding amount of strain; or the voice coil motor coil responds to the changes in magnitude and direction of the driving current signal and generates an electromagnetic driving force in a magnetic field with a corresponding direction and a corresponding amount of displacement.

[0014] The pushing end lens achieves minute displacements smaller than the detector pixel size in both the horizontal and vertical directions, and also includes: The mechanical deformation or the electromagnetic driving force is directly transmitted to the end lens fixedly connected to the micro-displacement driving mechanism, pushing the end lens to move horizontally or vertically in a two-dimensional plane perpendicular to the optical axis. The horizontal movement distance and the vertical movement distance are controlled by the amplitude of the driving voltage signal or the driving current signal, respectively, and both are smaller than the single pixel size of the focal plane detector, so as to achieve sub-pixel level displacement accuracy. The micro-displacement driving mechanism sequentially responds to multiple time-staggered driving voltage signals or driving current signals, driving the end lens to position itself according to a preset two-dimensional displacement trajectory to multiple preset sampling points, including the initial position, the horizontal positive direction sub-pixel offset position, the horizontal negative direction sub-pixel offset position, the vertical positive direction sub-pixel offset position, and the vertical negative direction sub-pixel offset position. At each preset sampling point, the timing control unit synchronously triggers the focal plane detector to acquire one frame of image, thereby forming a multi-frame low-resolution image sequence with regular two-dimensional sub-pixel displacement differences.

[0015] In this embodiment, the system timing control unit integrates a CPLD (Complex Programmable Logic Device) as the core of timing generation. After the device completes initialization upon power-on on the track, the micro-scanning timing logic program pre-programmed into the CPLD by technicians begins to run. It generates a weak initial sub-pixel-level displacement control signal according to the preset 2×2 sub-pixel sampling trajectory. This initial control signal has extremely low driving power and cannot directly drive the piezoelectric ceramic body to produce mechanical deformation. Therefore, the CPLD... A dedicated voltage amplifier circuit is connected to the signal output terminal to synchronously amplify the weak control signal in terms of voltage amplitude and output power, converting it into a high-voltage drive voltage signal that matches the working range of the piezoelectric ceramic. The amplified drive voltage signal is then time-divisionally input to the piezoelectric ceramic bodies arranged at four points around the circumference of the micro-displacement platform. Relying on the inverse piezoelectric effect, the piezoelectric ceramic material synchronously generates controllable mechanical deformation in the magnitude and direction of the input drive voltage signal, corresponding to the magnitude and polarity of the deformation. One end of the piezoelectric ceramic body is fixed to a fixed point on the camera housing, while the other end rigidly abuts against the outer ring of the end lens. The mechanical thrust generated by its deformation is directly transmitted to the end lens, causing it to translate independently along the horizontal X-axis or vertical Y-axis in a two-dimensional plane perpendicular to the system's main optical axis. The unidirectional movement distance of the lens is precisely controlled by the drive voltage amplitude, with the displacement value strictly controlled to be less than the physical size of a single pixel of the focal plane detector, thereby achieving micron-level sub-pixel displacement positioning accuracy. Multiple sets of driving voltage signals with different polarities and amplitudes are output in a staggered manner according to the timing. The piezoelectric ceramic body drives the end lens to complete multi-point positioning along a preset two-dimensional displacement trajectory in sequence. It stops at all preset sampling points in sequence, including the initial zero offset reference position, the horizontal positive subpixel offset position, the horizontal negative subpixel offset position, the vertical positive subpixel offset position, and the vertical negative subpixel offset position. When the piezoelectric ceramic drives the lens to reach any preset sampling point and completes the displacement stabilization, the CPLD synchronously outputs an exposure trigger pulse to the focal plane detector, triggering the detector to complete the single-frame image integration, charge conversion, and digital image readout operation at the current position. After the single-frame image is completely acquired, the CPLD switches to the next set of driving voltage signals, controlling the piezoelectric ceramic to push the lens to jump to the next subpixel sampling point. The displacement-stabilization-synchronous exposure acquisition process is repeated. After completely traversing all preset two-dimensional sampling points, a set of multi-frame low-resolution image sequences with regular spatial offset and standard subpixel position differences between each pair are finally output. These are then used by the back-end on-board preprocessing module to complete the correction and then transmitted to the ground for reconstruction.

[0016] The focal plane detector is located at the image-side focal plane of the imaging lens group. It is used to receive the light signal transmitted through the end lens and convert it into an electrical signal, and output multiple frames of images according to a preset frame period.

[0017] It should be understood that the specific process of outputting multiple frames of images according to a preset frame period is as follows; After the timing control unit is powered on, a reference clock signal is generated by the internal clock source. The main timing reference of the system is generated by frequency division based on the reference clock signal. The main timing reference of the system serves as both the displacement trigger reference of the micro-displacement drive mechanism and the frame exposure start reference of the focal plane detector, so as to ensure that the two are synchronized in the time domain. According to the preset micro-scanning sampling mode, at the beginning of each sampling cycle of the main timing reference of the system, the timing control unit simultaneously sends a displacement enable signal to the micro-displacement drive mechanism through the parallel timing output port, and sends a frame exposure start pulse to the focal plane detector. The frame exposure start pulse triggers the focal plane detector to start the integration exposure process of the current frame. During the preset integration time, each pixel of the focal plane detector accumulates the received light signal and converts it into a corresponding charge signal. After the integration time ends, the focal plane detector performs the conversion of the charge signal into a voltage signal, and the voltage signal is quantized into digital image data by the analog-to-digital converter to complete the acquisition of a single frame image.

[0018] The step of outputting multiple frames of images according to a preset frame period also includes: During the period when the focal plane detector completes single-frame image acquisition and reads out digital image data, the timing control unit keeps the micro-displacement drive mechanism locked at the current sub-pixel offset position and does not trigger new displacement actions to avoid image blurring caused by optical path jitter during exposure. After the focal plane detector completes the reading of the current frame image data, the timing control unit outputs a displacement control signal for the next sampling period to drive the micro-displacement drive mechanism to move the end lens to the next preset sub-pixel offset position. After the micro-displacement drive mechanism completes the displacement and reaches a stable state, the timing control unit outputs a frame exposure start pulse to the focal plane detector again to trigger the acquisition and reading of the next frame image. The focal plane detector sequentially acquires a frame image at multiple different sub-pixel offset positions of the end lens according to the frame period sequence output by the timing control unit, forming an output image sequence containing multiple low-resolution images. Each frame image has a corresponding frame number and position encoding information to identify the sub-pixel offset position of the end lens corresponding to that frame image.

[0019] In this embodiment, on-orbit imaging operations are carried out using a space situational awareness computational optical imaging system equipped with a CPLD timing control unit, a piezoelectric ceramic micro-displacement platform, and a focal plane array detector. After the system completes the on-board power-on process, the high-precision crystal oscillator clock source inside the timing control unit immediately starts oscillating and outputs a stable high-frequency reference clock signal. The timing logic module inside the CPLD performs multi-level frequency division operations on this reference clock to generate a unified system main timing reference pulse signal. This main timing reference serves as a globally unified time scale, synchronously supplying the displacement trigger channel of the micro-displacement drive mechanism and the exposure control channel of the focal plane detector. This eliminates the timing offset between displacement actions and image exposure at the underlying clock level, ensuring that the lens sub-pixel displacement and detector integration exposure actions are strictly aligned in the time dimension. The system pre-stores a complete set of timing parameters corresponding to the 2×2 micro-scan sampling mode in the CPLD, including single-frame integration duration, inter-frame interval, sampling period duration, and timing of all sub-pixel point switching, etc. When the system enters the target observation imaging mode, the CPLD... Using the system's main timing reference obtained through frequency division as the clock cycle, at the start of each complete sampling period, two control signals are synchronously output through multiple parallel timing output ports. One signal is a displacement enable signal sent to the piezoelectric ceramic drive circuit, and the other is a frame exposure start pulse sent to the exposure control pin of the focal plane detector. The rising edge of the frame exposure start pulse directly triggers the focal plane detector to start the photocharge integration exposure process for the current frame. Within a preset fixed integration time interval, each pixel of the detector continuously receives the spatial target beam converged by the end lens, continuously accumulating the incident photon energy and converting it into an analog charge signal. After the integration time ends, the internal charge readout circuit of the detector is activated, completing the conversion of the charge signal to an analog voltage signal line by line. The on-chip analog-to-digital converter synchronously quantizes and samples the analog voltage of each line, outputting the complete single-frame digital image raw data. This completes the acquisition of the single-frame image at the current sub-pixel position. During the entire working window period of the detector performing integration exposure, charge readout, and digital data output, the CPLD... The position latch level is continuously output to the piezoelectric ceramic driving circuit to keep the end lens of the piezoelectric ceramic drive locked at the current sub-pixel offset point. No new displacement control commands are output throughout the process, thus preventing the problem of image ghosting and edge blurring caused by slight lens shaking or displacement during exposure.Once the focal plane detector has read all pixel data for the entire frame and sends a frame readout completion status signal back to the CPLD, the CPLD immediately releases the current position latch and outputs the displacement control signal corresponding to the next sampling period. This signal is then converted into a driving voltage by a voltage amplifier circuit to drive the piezoelectric ceramic platform and move the end lens to the next preset sub-pixel sampling point. The system's built-in positioning detection circuit collects the piezoelectric ceramic deformation feedback signal in real time. Once the feedback signal determines that the lens displacement is in place, the mechanical vibration has completely decayed, and the platform has entered a stable state, the CPLD... The frame exposure start pulse is output again to the focal plane detector, initiating the integration exposure and data readout process for the next frame. This entire imaging acquisition process repeats cyclically. The focal plane detector follows the periodic timing sequence issued by the timing control unit, acquiring a complete low-resolution image frame corresponding to each distinct two-dimensional sub-pixel offset position of the end lens. All acquired image data are synchronously bound to a unique frame number and corresponding sub-pixel position code in the output buffer. The frame number distinguishes the order of image acquisition, and the position code records the horizontal and vertical offset of the end lens during that frame's imaging. After all positions are acquired, the buffer outputs a multi-frame low-resolution image sequence with complete identification information, which is directly sent to the onboard preprocessing module for blind pixel compensation, multi-point correction, and other preprocessing. This provides original image material with complete temporal matching and positional information for ground-based multi-frame fusion super-resolution reconstruction.

[0020] The timing control unit is electrically connected to the micro-displacement driving mechanism and the focal plane detector, respectively, and is used to generate synchronous timing control signals to obtain a multi-frame low-resolution image sequence. The timing control unit outputs a time-division driving signal according to a preset micro-scanning sampling mode to control the micro-displacement driving mechanism to drive the end lens to move sequentially to multiple preset sub-pixel offset positions, and synchronously triggers the focal plane detector to acquire one frame of image at each displacement position, thereby obtaining a multi-frame low-resolution image sequence.

[0021] It should be further explained that the specific process for obtaining the multi-frame low-resolution image sequence is as follows: The timing control unit has a built-in complex programmable logic device. After the system is powered on, the complex programmable logic device executes the internally embedded micro-scanning timing configuration program and reads the preset micro-scanning sampling parameters. The micro-scanning sampling parameters include sub-pixel displacement step size, two-dimensional displacement trajectory sequence, single frame integration time, inter-frame interval time, and total number of sampling frames. The complex programmable logic device generates a synchronous timing control signal containing multiple timing cycles based on the micro-scanning sampling parameters. The synchronous timing control signal is a composite control signal, and the parallel output terminal includes at least a first control terminal and a second control terminal. The first control terminal outputs a displacement driving pulse sequence for driving the micro-displacement driving mechanism, and the second control terminal outputs a frame exposure synchronization pulse sequence for triggering the focal plane detector. The displacement driving pulse sequence and the frame exposure synchronization pulse sequence have a preset phase difference timing relationship, specifically: Within each sampling cycle, the displacement drive pulse is output before the frame exposure synchronization pulse, and the time interval between the falling edge of the displacement drive pulse and the rising edge of the frame exposure synchronization pulse is greater than or equal to the settling time required for the micro-displacement drive mechanism to complete the sub-pixel displacement action and enter a stable state, so as to ensure that the end lens has accurately reached and stabilized at the target sub-pixel offset position before the focal plane detector starts the integral exposure.

[0022] The preset phase difference timing relationship between the frame exposure synchronization pulse sequence and the frame exposure synchronization pulse sequence also includes: The focal plane detector performs exposure acquisition and readout operations of a single frame image according to a preset integration time under the rising edge trigger of each frame exposure synchronization pulse, and returns a frame readout completion status flag to the complex programmable logic device when the current frame image data readout is completed. In response to receiving the frame readout completion status flag, the complex programmable logic device determines whether the number of frames currently acquired has reached the total number of sampling frames. If not, it continues to output the displacement drive pulse of the next sampling cycle, driving the micro-displacement drive mechanism to move the end lens to the next preset sub-pixel offset position, and outputs the next frame exposure synchronization pulse after receiving the displacement arrival feedback signal. If the target has been reached, the output of the synchronization timing control signal will be terminated, and the entire sampling process will be completed. The timing control unit synchronously controls the micro-displacement driving mechanism to sequentially step through all preset sub-pixel offset positions in time, and controls the focal plane detector to acquire an image frame at each offset position, thereby obtaining a set of multi-frame low-resolution image sequences with regular sub-pixel displacement differences in two-dimensional space. The total number of frames in the multi-frame low-resolution image sequence is equal to the preset total number of sampling frames, and each frame corresponds one-to-one with each preset sub-pixel offset position of the end lens at the acquisition time.

[0023] In this embodiment, a space situational awareness computational optical imaging system equipped with a CPLD timing control unit, a piezoelectric ceramic micro-displacement platform, and a focal plane array detector is applied. After the system completes its hardware self-test upon power-on in orbit, the micro-scanning timing configuration program stored internally in the timing control unit automatically starts running. The CPLD program first reads the complete set of micro-scanning sampling parameters pre-programmed into the on-chip non-volatile memory area. In this embodiment, a standard 2×2 imaging sampling mode is selected, with the corresponding parameters set as follows: the sub-pixel displacement step size is half the detector's single-pixel size; the two-dimensional displacement trajectory sequence is arranged sequentially by the origin, horizontal 1 / 2 pixel offset, vertical 1 / 2 pixel offset, and diagonal 1 / 2 pixel offset; the single-frame integration time is set to 8ms; the inter-frame interval time is set to 12ms; and the total number of sampling frames is fixed at 4 frames. After reading all parameters, the CPLD generates a sequence containing 4 frames based on the internal reference clock frequency division. The composite synchronization timing control signal for a complete sampling cycle is output in parallel via two paths. The first control terminal is connected to a piezoelectric ceramic driver amplifier circuit, continuously outputting a displacement drive pulse sequence. The second control terminal is directly connected to the exposure trigger pin of the focal plane detector, outputting a frame exposure synchronization pulse sequence. The two sets of pulse signals are pre-configured with fixed phase difference timing logic. Within each complete sampling cycle, the CPLD will prioritize outputting a displacement drive pulse from the first control terminal, with a 1-bit interval reserved between the falling edge of the first pulse and the rising edge of the frame exposure synchronization pulse from the second control terminal.A 5ms time interval is used, which is no less than the settling time required for the piezoelectric ceramic driving lens to complete subpixel translation, eliminate mechanical oscillations, and achieve complete stabilization. This ensures that the end lens is precisely positioned at the target subpixel sampling point before the focal plane detector starts integrating exposure, preventing image blurring and registration misalignment due to unstable lens displacement. After the rising edge of the frame exposure synchronization pulse is input to the detector, the detector starts 8ms of photocharge integration acquisition. After integration, charge conversion, quantization, and full-frame image data readout are completed line by line. Once a complete frame image is fully output, the detector sends a high-level frame readout completion status indicator to the CPLD. The CPLD monitors this feedback signal in real time. Upon receiving the indicator, it immediately compares the current cumulative number of acquired frames with the preset total number of 4 frames. If the current number of acquired frames is less than 4, it immediately outputs the displacement drive pulse corresponding to the next sampling cycle. The piezoelectric ceramic driving circuit controls the end lens to switch to the next subpixel offset position in the trajectory. Simultaneously, it continuously acquires the displacement positioning feedback signal of the piezoelectric ceramic platform. Only after receiving stable positioning feedback will the next frame exposure synchronization pulse be output. When the CPLD... When the cumulative number of acquired frames equals the preset total number of 4 frames, the pulse output of the two parallel control terminals is immediately cut off, terminating the entire micro-scanning sampling sequence. Throughout the process, the timing control unit relies on synchronous pulses with phase difference to strictly control the timing of lens displacement and image exposure, driving the micro-displacement mechanism to traverse all sub-pixel sampling points along a predetermined two-dimensional trajectory. The focal plane detector acquires a complete image frame at each independent offset position, ultimately resulting in a 4-frame low-resolution image sequence with the total number of frames matching the preset parameters, each frame matching the corresponding sub-pixel position of the lens, and a uniform two-dimensional spatial offset. This image sequence includes the offset position encoding information for each frame and is directly sent to the on-board preprocessing module for blind pixel compensation, multi-point correction, and other preprocessing, providing a time-matched, spatially precisely controllable raw image data source for ground-based multi-frame fusion super-resolution reconstruction.

[0024] The onboard preprocessing module is connected to the focal plane detector and is used to receive the multi-frame low-resolution image sequence, perform blind pixel compensation, multi-point correction and data format conversion on the image sequence, generate preprocessed image data, and transmit the preprocessed image data to the ground processing terminal through the satellite-to-ground data transmission link.

[0025] It should be understood that the on-board preprocessing module is connected to the focal plane detector via a high-speed data interface, receiving multi-frame low-resolution image sequences output by the focal plane detector in real time. Each frame of image data is sequentially written into the buffer memory within the on-board preprocessing module, carrying a corresponding frame number and sub-pixel offset position encoding information. The buffer memory temporarily stores the received multi-frame image data according to a first-in, first-out (FIFO) principle, awaiting subsequent processing. For blind pixel compensation processing: the on-board preprocessing module reads the currently pending frame of image data from the buffer memory and simultaneously calls the pre-stored blind pixel position mapping table of the array detector in its internal non-volatile memory. The blind pixel position mapping table records the position of each pixel of the focal plane detector. Response status identifier; The on-board preprocessing module traverses each pixel of the current frame image, queries the corresponding response status identifier in the blind pixel location mapping table based on its coordinates, and for pixel positions determined as blind pixels, interpolation replacement compensation is performed using the gray values ​​of its neighboring effective pixels. The interpolation replacement uses bilinear interpolation or median filtering algorithms to restore the effective gray value information at that position. For pixel positions determined as normal responses, their original gray values ​​are retained. This process is repeated for all pixels in the entire frame, and the first intermediate image data after blind pixel compensation is output. Multi-point correction processing: The on-board preprocessing module performs multi-point correction processing on the first intermediate image data. The multi-point correction processing includes at least dark level correction and gain non-uniformity correction. The dark level correction... To obtain the dark level reference value of the focal plane detector under no-light input conditions, the dark level reference value is subtracted from the gray values ​​of each pixel in the first intermediate image data to eliminate fixed-mode noise caused by the detector's dark current. The gain non-uniformity correction involves reading the pre-stored pixel gain correction coefficient matrix in the internal non-volatile memory, multiplying the gray values ​​of each pixel after dark level correction by the corresponding gain correction coefficient, and eliminating inconsistencies in the response sensitivity of each pixel. After multi-point correction processing, the second intermediate image data is output. Data format conversion: The on-board preprocessing module performs data format conversion on the second intermediate image data, converting the original parallel digital signal format output by the focal plane detector into a standard string suitable for satellite-to-ground data transmission. The data frame format conversion includes re-encapsulating the sampling bit depth of each pixel according to a preset quantization precision, adding a frame synchronization header, frame number, corresponding subpixel offset position code, acquisition timestamp, and image size information to the header of each frame of image data, and adding a frame check code to the tail of each frame of image data to complete the protocol encapsulation of the image data frame; data compression and downlink: the on-board preprocessing module sequentially combines the multi-frame image data after frame protocol encapsulation into a downlink data packet, and downlinks it to the ground processing end via the satellite-to-ground data transmission link at a preset transmission rate. During the transmission process, each frame of image data maintains the consistency of the association between the frame number and the subpixel offset position code, so as to provide the ground processing end with subsequent multi-frame image registration and fusion reconstruction processing.

[0026] The ground image reconstruction module, located at the ground processing end, receives the preprocessed image data and performs multi-frame fusion reconstruction processing on the multi-frame low-resolution image sequence with sub-pixel displacement differences. The ground image reconstruction module includes an interpolation reconstruction unit, a multi-frame fusion unit, and a noise suppression unit. The interpolation reconstruction unit constructs an initial high-resolution estimation image based on multiple low-resolution images. The multi-frame fusion unit fuses complementary information from each frame to improve spatial resolution. The noise suppression unit suppresses noise and false details during the fusion process, ultimately generating a high-resolution image for target recognition, orbit calculation, and status monitoring in space situational awareness.

[0027] It should be further explained that the specific process for multi-frame fusion and reconstruction of the column is as follows: The ground image reconstruction module receives a sequence of multiple low-resolution images and sub-pixel offset position encoding information corresponding to each frame from the on-board preprocessing module. Based on the sub-pixel offset position encoding of each frame, the module performs spatial registration on each low-resolution image to determine the relative spatial offset of each frame in the super-resolution reconstruction grid. The relative spatial offset is a sub-pixel fraction of the size of a single pixel of the focal plane detector in both the horizontal and vertical directions. After registration, the module outputs each frame and its corresponding sub-pixel offset coordinate mapping table. The ground image reconstruction module projects each frame of low-resolution image onto the target high-resolution grid according to the sub-pixel offset coordinate mapping table. For each grid point in the target high-resolution grid, it obtains the gray value of each frame of image pixels covering the grid point, calculates the initial gray value estimate of the grid point using a non-uniform interpolation method, and traverses all grid points of the target high-resolution grid to generate an initial high-resolution estimated image. The ground image reconstruction module performs structural optimization processing on the initial high-resolution estimated image, and uses a curvature-like interpolation algorithm to calculate the second-order difference value of each pixel in the initial high-resolution estimated image. Based on the second-order difference value, it determines whether the region where each pixel is located is an edge region or a smooth region.

[0028] The specific process for determining whether the region where each pixel is located is an edge region or a smooth region is as follows: For pixels in the edge region, adaptive interpolation is performed along the edge direction to maintain a sharp edge transition. For pixels in the smooth region, isotropic interpolation is used to suppress unnecessary texture disturbances, generating a high-resolution image with optimized structure. The ground image reconstruction module performs high-frequency detail extraction processing on the initial high-resolution estimated image, extracting high-frequency components from the initial high-resolution estimated image. The high-frequency components include high-frequency edge information and detail texture information of the target. A side suppression mechanism is applied to the high-frequency components. The side suppression mechanism calculates the difference between each pixel in the high-frequency components and its neighboring pixels. For pixels with a difference less than a preset noise threshold, they are determined to be noise or false details and are suppressed and filtered out. For pixels with a difference greater than or equal to the preset noise threshold, they are determined to be valid high-frequency details and are preserved and enhanced. After side suppression processing, the enhanced high-frequency detail image is output. The ground image reconstruction module fuses the structure-optimized high-resolution image with the enhanced high-frequency detail image. Using a pixel-level weighted fusion method, the gray values ​​of the structure-optimized high-resolution image and the enhanced high-frequency detail image are superimposed pixel by pixel according to a preset weight coefficient to generate a fused and reconstructed high-resolution image. The fused and reconstructed high-resolution image has both clear edge structure and high-frequency detail information, and the noise level is effectively suppressed.

[0029] In this embodiment, a sequence of four low-resolution images with subpixel offset codes is acquired in a 2×2 micro-scan sampling mode. The ground image reconstruction module first receives a complete data packet from the onboard preprocessing module via the satellite-to-ground communication link. The data packet contains four corrected low-resolution images, along with a unique subpixel offset position code for each image. The code precisely records the horizontal and vertical offset fractions of the end lens relative to the reference position during imaging of each frame, with each offset being half the size of a single pixel of the focal plane detector. The reconstruction module first initiates the spatial registration process, reading the offset position code corresponding to each image frame by frame, mapping each low-resolution image to a unified high-resolution reconstruction grid coordinate system, and calculating the horizontal and vertical subpixel-level fractional offsets of each image relative to the origin of the reconstruction grid. After the registration operation of all four images is completed, a complete subpixel offset coordinate mapping table is generated, recording the one-to-one correspondence between all pixels of each image and the high-resolution grid. Subsequently, the reconstruction module retrieves the coordinate mapping table to perform multi-frame pixel projection interpolation operations, projecting all four registered low-resolution images onto a preset 2 On the high-resolution grid magnified multiple times, for each independent grid point, the original pixel grayscale values ​​of all low-resolution images that spatially project to cover that grid point are traversed and filtered. A weighted non-uniform interpolation algorithm adapted to sub-pixel non-uniform sampling is used to solve for the grayscale value of that grid point. After completely traversing all grid points in the high-resolution grid in row and column order, an initial high-resolution estimated image with only basic contours and blurred edges is output. After the initial image is generated, the module starts image structure optimization processing, calling the built-in curvature-like interpolation algorithm to calculate the horizontal and vertical second order of the initial high-resolution estimated image pixel by pixel. The difference value distinguishes the region to which a pixel belongs by the magnitude of the second-order difference value. If the second-order difference value is higher than the preset region judgment threshold, the pixel is judged to be located in the target edge region. If it is lower than the threshold, it is judged to be a smooth background region of the starry sky. For pixels judged to be edge regions, the algorithm performs adaptive directional interpolation along the edge gradient direction and fills grayscale information along the edge extension direction to ensure that the contours of targets such as space debris and satellite bodies are sharp and without jagged edges. For pixels in the smooth region of the starry sky, isotropic uniform interpolation is used to eliminate the messy and false texture disturbances introduced by the interpolation operation. After the operation is completed, the high-resolution image with optimized structure is output.Simultaneously, the reconstruction module performs high-frequency detail extraction processing on the initial high-resolution estimated image in parallel. A high-pass filter operator separates the high-frequency components of the image, which carry effective target details such as the edges of small satellites and the surface texture of debris. Simultaneously, it removes false detail noise caused by detector noise and stray starlight. A side-suppression mechanism is applied to the extracted high-frequency components, calculating the grayscale difference between the current pixel and its four neighboring pixels (up, down, left, and right). A fixed noise discrimination threshold is pre-set. When the neighborhood difference is less than this threshold, the pixel is considered meaningless noise and false detail, and its grayscale is directly zeroed out. When the difference is greater than or equal to the threshold, it is identified as a true high-frequency detail, and its detail is enhanced by a fixed gain coefficient. The final output is an enhanced high-frequency detail image with noise removal and effective texture enhancement. Finally, the reconstruction module performs a pixel-level weighted fusion operation on both images. A preset fusion weight coefficient is retrieved, and the structure-optimized high-resolution image and the enhanced high-frequency detail image are superimposed pixel by pixel according to fixed weights. Smooth regions are given higher weights to the structure-optimized image, and edge detail regions are given higher weights to the enhanced high-frequency image. After superposition, the final fused and reconstructed high-resolution image is output.

[0030] It should be understood that the super-resolution information acquisition system consists of a lens, a focal plane array detector, a CPLD timing control unit, a high-performance DSP module, and a data storage module. The piezoelectric ceramic-based micro-scanning device uses a micro-scanning platform in the imaging system. The small input signal in micro-scanning imaging is generated by a complex programmable logic device (CPLD), which controls the piezoelectric ceramic to achieve micro-displacement via a voltage amplification circuit. The CPLD is responsible for the timing generation and control of the entire system, controlling its operation. The final lens used for imaging is fixed on a micro-motion platform with horizontal and vertical sliding rails. This platform has four piezoelectric ceramic bodies used to control the sub-pixel displacement of the lens in four directions. When a driving voltage is applied, the piezoelectric ceramic bodies in the micro-motion platform undergo corresponding physical deformation due to the inverse piezoelectric effect, pushing the lens to move and achieving micro-scanning. The lens operates in digital output mode, and the CPLD control signal output is synchronized with the lens micro-scanning, allowing the imaging detector to sequentially read out the image sequence signal. This signal is then processed by a high-performance DSP processor for blind pixel compensation, multi-point correction, etc., and finally converted from digital to analog (D / A) signal for storage and download. Computational optical imaging is then performed on the ground. The computational optical imaging process involves first inputting four low-resolution images with sub-pixel displacement, and then constructing an initial high-resolution estimated image using direct interpolation. Subsequently, curvature-like interpolation is used to optimize the image structure, making the edges smoother and more natural. Based on this, high-frequency detail information is extracted from the image, and noise and false details are suppressed through a lateral suppression mechanism. Finally, the structure optimization results and high-frequency enhancement results are fused to obtain a high-resolution reconstructed image with clear details and controlled noise. This algorithm constructs an initial image through multi-frame interpolation, uses second-order difference for adaptive edge interpolation, and combines lateral suppression to enhance high-frequency details, thereby improving the spatial resolution and edge sharpness of the reconstructed image while reducing computational complexity.

[0031] like Figure 7The diagram shows a flowchart of a computational optical imaging method for space situational awareness provided in an embodiment of this application. The method includes: an optical imaging lens group, comprising imaging lenses arranged sequentially along the optical path, wherein the imaging lens group has an end lens located closest to the image plane, the end lens being used to converge the target beam to the image plane; driving the end lens to generate sub-pixel-level displacement in a two-dimensional plane perpendicular to the optical axis, and generating corresponding physical deformation in response to driving voltage or driving current, thereby driving the end lens to achieve minute displacements smaller than the detector pixel size in both the horizontal and vertical directions; receiving the light signal transmitted through the end lens and converting it into an electrical signal, and outputting multiple frames of images according to a preset frame period; generating a synchronization timing control signal to obtain a sequence of multiple low-resolution images; receiving the sequence of multiple low-resolution images and performing blind pixel compensation, multi-point correction, and data format conversion on the image sequence to generate pre-processed image data, and transmitting the pre-processed image data to a ground processing end via a satellite-to-ground data transmission link; receiving the pre-processed image data and performing multi-frame fusion reconstruction processing on the sequence of multiple low-resolution images with sub-pixel displacement differences.

[0032] In this embodiment, the end lens of the imaging lens group is mounted on a piezoelectric ceramic-driven micro-displacement platform, achieving sub-pixel-level micro-displacement of the imaging lens in a two-dimensional direction under the drive of the control unit. The control unit outputs a time-division drive signal, causing the lens to sequentially complete preset two-dimensional displacement sampling, thereby forming a multi-frame low-resolution image sequence with slight spatial offsets on the detector. After basic correction by the on-board preprocessing module, the images are transmitted to the ground, where the image reconstruction module fuses the multi-frame images to obtain a high-resolution image. The micro-vibration drive mechanism is replaced with a dual-axis voice coil motor, and the micro-displacement control of the lens in a two-dimensional direction is achieved by controlling the current. This drive method can be extended to sub-pixel sampling modes of different scales to adapt to space target observation tasks with different resolution requirements. The system dynamically adjusts the micro-displacement sampling frequency according to the target's motion state. For low-speed targets, a low-frequency sampling mode is used to improve the signal-to-noise ratio; for high-speed targets, the sampling frequency is increased to reduce motion blur, thereby improving imaging stability.

[0033] Obviously, those skilled in the art can make various modifications and variations to this invention without departing from its spirit and scope. Therefore, if these modifications and variations fall within the scope of the claims of this invention and their equivalents, this invention also intends to include these modifications and variations.

Claims

1. A computational optical imaging system for space situational awareness, characterized in that, include: Optical imaging lens group, micro-displacement drive mechanism, focal plane detector, timing control unit, on-board preprocessing module and ground image reconstruction module; The optical imaging lens group includes an imaging lens group arranged sequentially along the optical path. The imaging lens group has an end lens located closest to the image plane. The end lens is used to converge the target beam to the image plane. The micro-displacement driving mechanism is used to drive the end lens to generate sub-pixel-level displacement in a two-dimensional plane perpendicular to the optical axis, and generate corresponding physical deformation in response to driving voltage or driving current, thereby driving the end lens to achieve micro-displacement smaller than the detector pixel size in the horizontal and vertical directions respectively. The focal plane detector is used to receive the light signal transmitted through the end lens and convert it into an electrical signal, and output multiple frames of images according to a preset frame period. The timing control unit is used to generate synchronous timing control signals to obtain a multi-frame low-resolution image sequence. The on-board preprocessing module is used to receive the multi-frame low-resolution image sequence, perform blind pixel compensation, multi-point correction and data format conversion on the image sequence, generate preprocessed image data, and transmit the preprocessed image data to the ground processing terminal through the satellite-to-ground data transmission link. The ground image reconstruction module is used to receive the preprocessed image data and perform multi-frame fusion reconstruction processing on the multi-frame low-resolution image sequence with sub-pixel displacement differences.

2. The computational optical imaging system for space situational awareness as described in claim 1, characterized in that, The specific process for achieving minute displacements smaller than the detector pixel size in both the horizontal and vertical directions of the driving end lens is as follows: The micro-displacement driving mechanism includes a piezoelectric ceramic driver or a voice coil motor; The timing control unit has a built-in complex programmable logic device, which generates an initial sub-pixel level displacement control signal according to a preset micro-scanning timing logic. The initial subpixel-level displacement control signal is amplified by a voltage amplification circuit or a current amplification circuit connected to the output terminal of the complex programmable logic device, and converted into a driving voltage signal or a driving current signal that drives the micro-displacement driving mechanism to produce physical deformation. The driving voltage signal or driving current signal is applied to the piezoelectric ceramic body or voice coil motor coil of the micro-displacement driving mechanism. The piezoelectric ceramic body, based on the inverse piezoelectric effect, responds to the changes in amplitude and polarity of the driving voltage signal and generates mechanical deformation in a corresponding direction and with a corresponding amount of strain; or the voice coil motor coil responds to the changes in magnitude and direction of the driving current signal and generates an electromagnetic driving force in a magnetic field with a corresponding direction and a corresponding amount of displacement.

3. The computational optical imaging system for space situational awareness as described in claim 2, characterized in that, The pushing end lens achieves minute displacements smaller than the detector pixel size in both the horizontal and vertical directions, and also includes: The mechanical deformation or the electromagnetic driving force is directly transmitted to the end lens fixedly connected to the micro-displacement driving mechanism, pushing the end lens to move horizontally or vertically in a two-dimensional plane perpendicular to the optical axis. The horizontal movement distance and the vertical movement distance are controlled by the amplitude of the driving voltage signal or the driving current signal, respectively, and both are smaller than the single pixel size of the focal plane detector, so as to achieve sub-pixel level displacement accuracy. The micro-displacement driving mechanism sequentially responds to multiple time-staggered driving voltage signals or driving current signals, driving the end lens to position itself according to a preset two-dimensional displacement trajectory to multiple preset sampling points, including the initial position, the horizontal positive direction sub-pixel offset position, the horizontal negative direction sub-pixel offset position, the vertical positive direction sub-pixel offset position, and the vertical negative direction sub-pixel offset position. At each preset sampling point, the timing control unit synchronously triggers the focal plane detector to acquire one frame of image, thereby forming a multi-frame low-resolution image sequence with regular two-dimensional sub-pixel displacement differences.

4. The computational optical imaging system for space situational awareness as described in claim 1, characterized in that, The specific process of outputting multiple frames of images according to a preset frame period is as follows: After the timing control unit is powered on, a reference clock signal is generated by the internal clock source. The main timing reference of the system is generated by frequency division based on the reference clock signal. The main timing reference of the system serves as both the displacement trigger reference of the micro-displacement drive mechanism and the frame exposure start reference of the focal plane detector, so as to ensure that the two are synchronized in the time domain. According to the preset micro-scanning sampling mode, at the beginning of each sampling cycle of the main timing reference of the system, the timing control unit simultaneously sends a displacement enable signal to the micro-displacement drive mechanism through the parallel timing output port, and sends a frame exposure start pulse to the focal plane detector. The frame exposure start pulse triggers the focal plane detector to start the integration exposure process of the current frame. During the preset integration time, each pixel of the focal plane detector accumulates the received light signal and converts it into a corresponding charge signal. After the integration time ends, the focal plane detector performs the conversion of the charge signal into a voltage signal, and the voltage signal is quantized into digital image data by the analog-to-digital converter to complete the acquisition of a single frame image.

5. The computational optical imaging system for space situational awareness as described in claim 4, characterized in that, The step of outputting multiple frames of images according to a preset frame period also includes: During the period when the focal plane detector completes single-frame image acquisition and reads out digital image data, the timing control unit keeps the micro-displacement drive mechanism locked at the current sub-pixel offset position and does not trigger new displacement actions to avoid image blurring caused by optical path jitter during exposure. After the focal plane detector completes the reading of the current frame image data, the timing control unit outputs a displacement control signal for the next sampling period to drive the micro-displacement drive mechanism to move the end lens to the next preset sub-pixel offset position. After the micro-displacement drive mechanism completes the displacement and reaches a stable state, the timing control unit outputs a frame exposure start pulse to the focal plane detector again to trigger the acquisition and reading of the next frame image. The focal plane detector sequentially acquires a frame image at multiple different sub-pixel offset positions of the end lens according to the frame period sequence output by the timing control unit, forming an output image sequence containing multiple low-resolution images. Each frame image has a corresponding frame number and position encoding information to identify the sub-pixel offset position of the end lens corresponding to that frame image.

6. The computational optical imaging system for space situational awareness as described in claim 1, characterized in that, The specific process for obtaining a multi-frame low-resolution image sequence is as follows: The timing control unit has a built-in complex programmable logic device. After the system is powered on, the complex programmable logic device executes the internally embedded micro-scanning timing configuration program and reads the preset micro-scanning sampling parameters. The micro-scanning sampling parameters include sub-pixel displacement step size, two-dimensional displacement trajectory sequence, single frame integration time, inter-frame interval time, and total number of sampling frames. The complex programmable logic device generates a synchronous timing control signal containing multiple timing cycles based on the micro-scanning sampling parameters. The synchronous timing control signal is a composite control signal, and the parallel output terminal includes at least a first control terminal and a second control terminal. The first control terminal outputs a displacement driving pulse sequence for driving the micro-displacement driving mechanism, and the second control terminal outputs a frame exposure synchronization pulse sequence for triggering the focal plane detector. The displacement driving pulse sequence and the frame exposure synchronization pulse sequence have a preset phase difference timing relationship, specifically: Within each sampling cycle, the displacement drive pulse is output before the frame exposure synchronization pulse, and the time interval between the falling edge of the displacement drive pulse and the rising edge of the frame exposure synchronization pulse is greater than or equal to the settling time required for the micro-displacement drive mechanism to complete the sub-pixel displacement action and enter a stable state, so as to ensure that the end lens has accurately reached and stabilized at the target sub-pixel offset position before the focal plane detector starts the integral exposure.

7. The computational optical imaging system for space situational awareness as described in claim 6, characterized in that, The preset phase difference timing relationship between the frame exposure synchronization pulse sequence and the frame exposure synchronization pulse sequence also includes: The focal plane detector performs exposure acquisition and readout operations of a single frame image according to a preset integration time under the rising edge trigger of each frame exposure synchronization pulse, and returns a frame readout completion status flag to the complex programmable logic device when the current frame image data readout is completed. In response to receiving the frame readout completion status flag, the complex programmable logic device determines whether the number of frames currently acquired has reached the total number of sampling frames. If not, it continues to output the displacement drive pulse of the next sampling cycle, driving the micro-displacement drive mechanism to move the end lens to the next preset sub-pixel offset position, and outputs the next frame exposure synchronization pulse after receiving the displacement arrival feedback signal. If the target has been reached, the output of the synchronization timing control signal will be terminated, and the entire sampling process will be completed. The timing control unit synchronously controls the micro-displacement driving mechanism to sequentially step through all preset sub-pixel offset positions in time, and controls the focal plane detector to acquire an image frame at each offset position, thereby obtaining a set of multi-frame low-resolution image sequences with regular sub-pixel displacement differences in two-dimensional space. The total number of frames in the multi-frame low-resolution image sequence is equal to the preset total number of sampling frames, and each frame corresponds one-to-one with each preset sub-pixel offset position of the end lens at the acquisition time.

8. The computational optical imaging system for space situational awareness as described in claim 1, characterized in that, The specific process for multi-frame fusion and reconstruction of the column is as follows: The ground image reconstruction module receives a sequence of multiple low-resolution images and sub-pixel offset position encoding information corresponding to each frame from the on-board preprocessing module. Based on the sub-pixel offset position encoding of each frame, the module performs spatial registration on each low-resolution image to determine the relative spatial offset of each frame in the super-resolution reconstruction grid. The relative spatial offset is a sub-pixel fraction of the size of a single pixel of the focal plane detector in both the horizontal and vertical directions. After registration, the module outputs each frame and its corresponding sub-pixel offset coordinate mapping table. The ground image reconstruction module projects each frame of low-resolution image onto the target high-resolution grid according to the sub-pixel offset coordinate mapping table. For each grid point in the target high-resolution grid, it obtains the gray value of each frame of image pixels covering the grid point, calculates the initial gray value estimate of the grid point using a non-uniform interpolation method, and traverses all grid points of the target high-resolution grid to generate an initial high-resolution estimated image. The ground image reconstruction module performs structural optimization processing on the initial high-resolution estimated image, and uses a curvature-like interpolation algorithm to calculate the second-order difference value of each pixel in the initial high-resolution estimated image. Based on the second-order difference value, it determines whether the region where each pixel is located is an edge region or a smooth region.

9. The computational optical imaging system for space situational awareness as described in claim 8, characterized in that, The specific process for determining whether the region where each pixel is located is an edge region or a smooth region is as follows: For pixels in the edge region, adaptive interpolation is performed along the edge direction to maintain a sharp edge transition. For pixels in the smooth region, isotropic interpolation is used to suppress unnecessary texture disturbances, generating a high-resolution image with optimized structure. The ground image reconstruction module performs high-frequency detail extraction processing on the initial high-resolution estimated image, extracting high-frequency components from the initial high-resolution estimated image. The high-frequency components include high-frequency edge information and detail texture information of the target. A side suppression mechanism is applied to the high-frequency components. The side suppression mechanism calculates the difference between each pixel in the high-frequency components and its neighboring pixels. For pixels with a difference less than a preset noise threshold, they are determined to be noise or false details and are suppressed and filtered out. For pixels with a difference greater than or equal to the preset noise threshold, they are determined to be valid high-frequency details and are preserved and enhanced. After side suppression processing, the enhanced high-frequency detail image is output. The ground image reconstruction module fuses the structure-optimized high-resolution image with the enhanced high-frequency detail image. Using a pixel-level weighted fusion method, the gray values ​​of the structure-optimized high-resolution image and the enhanced high-frequency detail image are superimposed pixel by pixel according to a preset weight coefficient to generate a fused and reconstructed high-resolution image. The fused and reconstructed high-resolution image has both clear edge structure and high-frequency detail information, and the noise level is effectively suppressed.

10. A computational optical imaging method for space situational awareness, characterized in that, The computational optical imaging system for space situational awareness as described in any one of claims 1-9 includes the following steps: An optical imaging lens group includes an imaging lens group arranged sequentially along an optical path, the imaging lens group having an end lens located closest to the image plane, the end lens being used to converge a target beam onto the image plane; The driving end lens generates a sub-pixel displacement in a two-dimensional plane perpendicular to the optical axis, and generates a corresponding physical deformation in response to the driving voltage or driving current, thereby driving the end lens to achieve a tiny displacement smaller than the detector pixel size in the horizontal and vertical directions respectively. It receives the light signal transmitted through the end lens and converts it into an electrical signal, and outputs multiple frames of images according to a preset frame period; Generate synchronous timing control signals to obtain a multi-frame low-resolution image sequence; The system receives the multi-frame low-resolution image sequence, performs blind pixel compensation, multi-point correction and data format conversion on the image sequence to generate preprocessed image data, and then transmits the preprocessed image data to the ground processing end through the satellite-to-ground data transmission link. The preprocessed image data is received, and multi-frame fusion reconstruction processing is performed on the low-resolution image sequence with sub-pixel displacement differences.

Images