Dark target enhancement device and method based on range gating polarization imaging

Abstract

The invention belongs to the technical field of photoelectric detection imaging, and particularly relates to a dim target enhancement device and method based on range gating polarization imaging, the device comprises a transmitting system and a receiving system, the transmitting system comprises a pulse laser, a signal modulation circuit and a transmitting optical system; the pulse laser is used for emitting laser beams; the signal modulation circuit is used for generating a high-frequency modulation electric signal and modulating a laser beam emitted by the pulse laser; the emission optical system is used for focusing and adjusting the light beam direction and the emergent light polarization state; the receiving system comprises a receiving optical system, a focal plane polarization detector, a synchronous control board, a signal processing board, an image processing board and display control equipment; according to the device, the pulse illumination module, the time synchronization control module and the polarization imaging module are integrated, and an image definition evaluation algorithm is combined, so that synchronous acquisition and fusion of target polarization information and distance information are realized.

Description

Technical Field

[0001] This application belongs to the field of photoelectric detection and imaging technology, and in particular relates to a device and method for enhancing dark and weak targets based on range-gated polarization imaging. Background Technology

[0002] Detecting faint targets against complex backgrounds remains a significant technical challenge in fields such as space exploration, underwater imaging, and military reconnaissance. Traditional optical imaging methods suffer severe signal attenuation and a marked decrease in image signal-to-noise ratio and contrast under the influence of strong light interference, atmospheric scattering, or similar backgrounds. Although polarization imaging technology can enhance detection capabilities by utilizing the difference in polarization characteristics between the target and the background—for example, by leveraging the smooth surface of artificial targets and their superior polarization-preserving properties compared to natural backgrounds—existing methods still have significant limitations in real-world combat environments.

[0003] Current technical bottlenecks include: First, conventional polarization imaging is susceptible to strong light scattering, making it difficult to effectively separate target reflected light from background interference light, especially at long distances or in harsh environments, where the polarization signal-to-noise ratio drops rapidly; second, the non-ideal nature of polarization devices (such as extinction ratio and transmittance loss) reduces system sensitivity, and traditional models do not fully incorporate range gating techniques, resulting in low detection efficiency for distant, dim targets; finally, existing methods mostly rely on fixed parameters and lack the ability to adaptively adjust to scene light intensity and target distance, making it impossible to optimize imaging clarity in real time.

[0004] Existing technology, such as Chinese invention patent publication number CN110297253A entitled "Enhanced Sonar-Assisted Range-Gated Laser Underwater Imaging Device and Method," discloses an enhanced sonar-assisted range-gated laser underwater imaging device and method, including a dual-laser enhanced illumination design and a sonar-assisted target range and azimuth pre-detection system. This invention increases the illumination intensity on the target through an enhanced dual-laser illumination system, thereby increasing the target detection range. Furthermore, the sonar detection system can pre-detect the target's range and azimuth, and through an embedded processing module, more precisely control the range gating control circuit's receiver detector window time, as well as control the intensity, azimuth, and polarization state of the laser source, aiming to achieve high-quality long-range imaging detection of the target.

[0005] While the aforementioned patents have enhanced the underwater laser detection capabilities, they still suffer from issues such as limited target detection dimensions, weak anti-interference capabilities in complex backgrounds, insufficient imaging accuracy and detail extraction capabilities, and system adaptability and scene limitations. Summary of the Invention

[0006] To overcome the aforementioned deficiencies in the prior art, this application proposes a device and method for enhancing faint targets based on range-gated polarization imaging.

[0007] To achieve the above-mentioned technical effects, the technical solution of this application is as follows: A device for enhancing the performance of faint targets based on range-gated polarization imaging includes a transmitting system and a receiving system; The transmitting system includes a pulsed laser, a signal modulation circuit, and a transmitting optical system; The pulsed laser is used to emit a laser beam; The signal modulation circuit is used to generate a high-frequency modulation electrical signal to modulate the laser beam emitted by the pulsed laser. The emission optical system is used to focus, adjust the beam direction and polarization state of the emitted light; The receiving system includes a receiving optical system, a focal plane polarization detector, a synchronization control board, a signal processing board, an image processing board, and a display and control device; The receiving optical system is used for imaging, image processing, and adaptive system control; The focal plane polarization detector is used to acquire the intensity map of the linear polarizer angle in real time, and then the Stokes vector characterization matrix and the linear polarization degree map are calculated in real time through the signal processing board. The synchronization control board is used to achieve high-precision time-delay synchronization control between laser pulse emission and detector shutter opening. The image processing board is used to acquire polarization information and, through focal plane array technology or micro-polarization array, simultaneously obtains intensity maps at four polarization detection angles (0°, 45°, 90°, 135°) in a single exposure. The display and control device is used for human-computer interaction control, enabling real-time imaging display and parameter adjustment.

[0008] Furthermore, the focal plane polarization detector is a short-wave infrared focal plane polarization imaging detector.

[0009] Furthermore, the center wavelength of the laser beam emitted by the pulsed laser is 1550 nm.

[0010] Furthermore, the signal modulation circuit modulates the laser beam to form an emitted laser with high peak power, narrow pulse width, and high repetition rate.

[0011] Furthermore, the emission optical system includes a fast-reflecting mirror and a controllable linear polarizer.

[0012] Furthermore, the focal plane polarization detector is used to acquire intensity maps (I) of linear polarizers at angles of (0°, 45°, 90°, 135°) in real time. 0° , I 45° , I 90° , I 135°Then, the Stokes vector representation matrix and the degree of linear polarization map (DOLP) are calculated in real time through the signal processing board. These four parameters form a 4×1 matrix vector as follows.

[0013] S is called the Stokes vector, where:

[0014]

[0015]

[0016] It is zero.

[0017] Therefore, the degree of linear polarization (DOLP) of any polarized light is: .

[0018] A method for enhancing faint targets based on range-gated polarization imaging includes the following steps: Step S1. Obtain the target distance d, calculate the power required by the pulsed laser based on the target distance d, adjust the optical parameters of the emission system, and set the laser beam divergence angle and target position; Step S2. A high-frequency modulation electrical signal is generated by the signal modulation circuit to modulate the output laser beam of the pulsed laser, forming a high peak power, narrow pulse width and high repetition rate emitted laser. Step S3. Using distance-gated illumination, a high-precision time-delay synchronization control of laser pulse emission and detector shutter opening is achieved through a synchronization control board, so that the laser pulse reflected from the target area reaches the detector and forms an image within the shutter opening time, suppressing backscattered light and scattered light from other distances. Step S4. Using a short-wave infrared focal plane polarization imaging detector, intensity maps (I) at linear polarizer angles of (0°, 45°, 90°, 135°) are acquired in real time. 0° , I 45° , I 90° , I 135° ); Step S5. Calculate the Stokes vector representation matrix and linear polarization degree map (DOLP) based on the acquired intensity map using the signal processing board; Step S6. Adjust the laser beam direction using the fast-reflecting mirror of the emission optics system to illuminate the target area, and control the controllable linear polarizer to rotate 360°. Simultaneously calculate the average gradient of the linear polarization degree diagram in the central field of view, stop the rotation at the position of the maximum average gradient, and record the polarization degree diagram at this time as P. max ; Step S7. Extract the linear polarization map P using the operator. max High-frequency features were analyzed to separate the high-frequency detail layer, and the total light intensity in the Stokes vector was determined. As a low-frequency image, the high-frequency detail layer and the low-frequency image are linearly weighted to output an enhanced image. .

[0019] Furthermore, in step S7, an enhanced image is output. ,in For high-frequency detail layers, These are the weighting coefficients.

[0020] Furthermore, in step S7, the operator for extracting high-frequency features is a guided filter operator, which is used to extract detailed information such as edges and textures.

[0021] The advantages of this application are: 1. This application organically combines range gating technology with polarization imaging technology. Through high-precision synchronous control, it achieves selective reception of target light at a specific distance, effectively suppressing backscattering and scattering interference from other distances. It utilizes the difference in polarization characteristics to highlight target details, and combines high-frequency feature extraction and image fusion technology to significantly improve image contrast and signal-to-noise ratio.

[0022] 2. This application uses a polarization camera and a pulsed laser for imaging. The equipment has stable performance and strong anti-interference ability. The method has a clear process and is highly operable. It can significantly improve the detection range and tracking stability of faint targets in complex backgrounds. It is applicable to multiple fields such as aerospace, security monitoring, and remote sensing. 3. This application employs multi-dimensional detection fusion, enhancing the ability to suppress complex backgrounds and achieving dynamic polarization optimization. It can adapt to different target characteristics. A controllable linear polarizer and a fast-reflecting mirror work together, and by rotating the polarizer and calculating the average gradient of the central field of view (DOLP), the optimal polarization state is locked at the position of maximum value. The polarization state of the illumination light is dynamically adjusted according to the target's reflection characteristics, maximizing the polarization difference between the target and the background. Compared to illumination with a fixed polarization state, the target contrast is significantly improved.

[0023] 4. This application uses a fast-reflecting mirror to adjust the pointing mechanism, which can be used for integrated transmission and reception, or for the laser and imaging functions to be implemented separately.

[0024] 5. This application utilizes a synchronization control board to achieve high-precision time-delay synchronization of laser and shutter, enabling precise interception of target echo periods using distance gating technology and effectively suppressing background stray light. It employs techniques such as acquiring multi-angle intensity maps using a split-plane polarization detector and calculating Stokes vectors and DOLP, thereby improving the difference in polarization characteristics between the target and background and enhancing the signal-to-noise ratio. Furthermore, by automatically adjusting laser power and beam parameters based on the target distance d and automatically selecting the optimal polarization angle using DOLP gradient feedback, an adaptive adjustment mechanism is introduced to dynamically optimize imaging parameters, achieving high contrast and real-time enhanced detection of faint targets against a noisy background. Attached Figure Description

[0025] Figure 1 This is a diagram showing the components of this device.

[0026] Figure 2 This is a flowchart of the method. Detailed Implementation

[0027] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. The components of the embodiments of this application described and shown in the accompanying drawings can generally be arranged and designed in various different configurations.

[0028] Therefore, the following detailed description of the embodiments of this application provided in the accompanying drawings is not intended to limit the scope of the claimed application, but merely to illustrate selected embodiments of the application. All other embodiments obtained by those skilled in the art based on the embodiments of this application without inventive effort are within the scope of protection of this application.

[0029] It should be noted that similar labels and letters in the following figures indicate similar items. Therefore, once an item is defined in one figure, it does not need to be further defined and explained in subsequent figures.

[0030] In the description of this application, it should be noted that the terms "upper," "vertical," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, or the orientation or positional relationship commonly used when the product is in use, or the orientation or positional relationship commonly understood by those skilled in the art. They are used only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation on this application. In addition, the terms "first," "second," etc., are only used to distinguish descriptions and should not be construed as indicating or implying relative importance.

[0031] In the description of this application, it should also be noted that, unless otherwise expressly specified and limited, the terms "set," "install," and "connect" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this application based on the specific circumstances.

[0032] Example 1 This embodiment discloses a device for enhancing the visibility of faint targets based on range-gated polarization imaging, including a transmitting system and a receiving system; The transmitting system includes a pulsed laser, a signal modulation circuit, and a transmitting optical system; Pulsed lasers are used to emit laser beams; The signal modulation circuit is used to generate a high-frequency modulation electrical signal to modulate the laser beam emitted by the pulsed laser. The transmitting optical system is used to focus, adjust the beam direction, and determine the polarization state of the emitted light; The receiving system includes a receiving optical system, a focal plane polarization detector, a synchronization control board, a signal processing board, an image processing board, and display and control equipment; The receiving optical system is used for imaging, image processing, and adaptive system control; the receiving optical system includes an optical camera.

[0033] The focal plane polarization detector is used to acquire the intensity map of the linear polarizer angle in real time, and then the Stokes vector representation matrix and the degree of linear polarization map (DOLP) are calculated in real time by the signal processing board. The synchronization control board is used to achieve high-precision time-delay synchronization control between laser pulse emission and detector shutter opening; The image processing board is used to acquire polarization information, and through focal plane array technology or micro-polarization array, it simultaneously acquires intensity maps at four polarization analysis angles (0°, 45°, 90°, 135°) in a single exposure. Display and control equipment is used for human-computer interaction control, enabling real-time imaging display and parameter adjustment.

[0034] This device integrates pulsed illumination, time synchronization control, and polarization imaging modules, combined with an image sharpness evaluation algorithm, to achieve synchronous acquisition and fusion of target polarization and distance information.

[0035] Example 2 This embodiment discloses a device for enhancing the visibility of faint targets based on range-gated polarization imaging, including a transmitting system and a receiving system; The transmitting system includes a pulsed laser, a signal modulation circuit, and a transmitting optical system; Pulsed lasers are used to emit laser beams; The signal modulation circuit is used to generate a high-frequency modulation electrical signal to modulate the laser beam emitted by the pulsed laser. The transmitting optical system is used to focus, adjust the beam direction, and determine the polarization state of the emitted light; The receiving system includes a receiving optical system, a focal plane polarization detector, a synchronization control board, a signal processing board, an image processing board, and display and control equipment; The receiving optical system is used for imaging, image processing, and adaptive system control; the receiving optical system includes an optical camera.

[0036] The focal plane polarization detector is used to acquire the intensity map of the linear polarizer angle in real time, and then the Stokes vector representation matrix and the degree of linear polarization map (DOLP) are calculated in real time by the signal processing board. The synchronization control board is used to achieve high-precision time-delay synchronization control between laser pulse emission and detector shutter opening; The image processing board is used to acquire polarization information, and through focal plane array technology or micro-polarization array, it simultaneously acquires intensity maps at four polarization analysis angles (0°, 45°, 90°, 135°) in a single exposure. Display and control equipment is used for human-computer interaction control, enabling real-time imaging display and parameter adjustment.

[0037] The focal plane polarization detector is a short-wave infrared focal plane polarization imaging detector.

[0038] The center wavelength of the laser beam emitted by the pulsed laser is 1550nm.

[0039] The signal modulation circuit modulates the laser beam to form a high peak power, narrow pulse width and high repetition rate emitted laser.

[0040] The emission optical system includes a fast-reflecting mirror and a controllable linear polarizer.

[0041] A split-focus plane polarization detector is used to acquire intensity maps (I) of linear polarizers at angles of (0°, 45°, 90°, 135°) in real time. 0° , I 45° , I 90° , I 135° Then, the Stokes vector characterization matrix and the degree of linear polarization map (DOLP) are calculated in real time through the signal processing board. The Stokes vector is currently the most commonly used method for representing polarization states because it can describe the polarization state of light through directly measured intensity parameters. These four parameters form a 4×1 matrix vector as follows:

[0042] S is called the Stokes vector, where:

[0043]

[0044]

[0045] The corresponding circularly polarized light component is relatively weak, and is approximately zero in general engineering.

[0046] Therefore, the degree of linear polarization (DOLP) of any polarized light is: .

[0047] This application organically combines range gating technology with polarization imaging technology. Through high-precision synchronous control, it achieves selective reception of target light at a specific distance, effectively suppressing backscattering and scattering interference from other distances. It utilizes the difference in polarization characteristics to highlight target details, and combines high-frequency feature extraction and image fusion technology to significantly improve image contrast and signal-to-noise ratio.

[0048] Imaging with a polarization camera and a pulsed laser together provides stable equipment performance, strong anti-interference capabilities, a clear methodology, and high operability. It can significantly improve the detection range and tracking stability of faint targets in complex backgrounds and is applicable to multiple fields such as aerospace, security monitoring, and remote sensing. Employing multi-dimensional detection fusion enhances the ability to suppress complex backgrounds and achieves dynamic polarization optimization, it can adapt to different target characteristics. A controllable linear polarizer and a fast-reflecting mirror work together to lock the optimal polarization state at its maximum value by rotating the polarizer and calculating the average gradient of the central field of view (DOLP). The polarization state of the illumination light is dynamically adjusted according to the target's reflection characteristics to maximize the polarization difference between the target and the background, resulting in a significant improvement in target contrast compared to fixed polarization illumination.

[0049] This application uses a fast-reflecting mirror to adjust the pointing mechanism, which can be used for integrated transmission and reception, or for separate laser and imaging functions.

[0050] Example 3 This embodiment discloses a method for enhancing faint targets based on range-gated polarization imaging, including the following steps: Step S1. Obtain the target distance d, calculate the power required by the pulsed laser based on the target distance d, adjust the optical parameters of the emission system, and set the laser beam divergence angle and target position; Step S2. A high-frequency modulation electrical signal is generated by the signal modulation circuit to modulate the output laser beam of the pulsed laser with a center wavelength of 1550nm, thereby forming an emitted laser with high peak power, narrow pulse width and high repetition rate. Step S3. Using distance-gated illumination, a high-precision time-delay synchronization control of laser pulse emission and detector shutter opening is achieved through a synchronization control board, so that the laser pulse reflected from the target area reaches the detector and forms an image within the shutter opening time, suppressing backscattered light and scattered light from other distances. Step S4. Using a short-wave infrared focal plane polarization imaging detector, intensity maps (I) at linear polarizer angles of (0°, 45°, 90°, 135°) are acquired in real time. 0° , I 45° , I 90° , I 135° ); Step S5. Calculate the Stokes vector representation matrix and linear polarization degree map (DOLP) based on the acquired intensity map using the signal processing board; Step S6. Adjust the laser beam direction using the fast-reflecting mirror of the emission optics system to illuminate the target area, and control the controllable linear polarizer to rotate 360°. Simultaneously calculate the average gradient of the linear polarization degree map (DOLP) in the central field of view. Stop the rotation at the position where the average gradient reaches its maximum value and record the DOLP at this point as P. max ; Step S7. Extract the degree of linear polarization (DOLP) map P using operators. max High-frequency features were analyzed to separate the high-frequency detail layer, and the total light intensity in the Stokes vector was determined. As a low-frequency image, the high-frequency detail layer and the low-frequency image are linearly weighted to output an enhanced image. .

[0051] Example 4 A method for enhancing faint targets based on range-gated polarization imaging includes the following steps: Step S1. Obtain the target distance d, calculate the power required by the pulsed laser based on the target distance d, adjust the optical parameters of the emission system, and set the laser beam divergence angle and target position; Step S2. A high-frequency modulation electrical signal is generated by the signal modulation circuit to modulate the output laser beam of the pulsed laser with a center wavelength of 1550nm, thereby forming an emitted laser with high peak power, narrow pulse width and high repetition rate. Step S3. Using distance-gated illumination, a high-precision time-delay synchronization control of laser pulse emission and detector shutter opening is achieved through a synchronization control board, so that the laser pulse reflected from the target area reaches the detector and forms an image within the shutter opening time, suppressing backscattered light and scattered light from other distances. Step S4. Using a short-wave infrared focal plane polarization imaging detector, intensity maps (I) at linear polarizer angles of (0°, 45°, 90°, 135°) are acquired in real time. 0° , I45° , I 90° , I 135° ); Step S5. Calculate the Stokes vector representation matrix and linear polarization degree map (DOLP) based on the acquired intensity map using the signal processing board; Step S6. Adjust the laser beam direction using the fast-reflecting mirror of the emission optics system to illuminate the target area, and control the controllable linear polarizer to rotate 360°. Simultaneously calculate the average gradient of the linear polarization degree map (DOLP) in the central field of view. Stop the rotation at the position where the average gradient reaches its maximum value and record the DOLP at this point as P. max ; Step S7. Extract the degree of linear polarization (DOLP) map P using operators. max High-frequency features were analyzed to separate the high-frequency detail layer, and the total light intensity in the Stokes vector was determined. As a low-frequency image, the high-frequency detail layer and the low-frequency image are linearly weighted to output an enhanced image. Output enhanced image ,in For high-frequency detail layers, The weighting coefficients effectively improve image contrast and signal-to-noise ratio. The operator for extracting high-frequency features is the guided filter operator, which is used to extract details such as edges and textures.

[0052] Example 5 Based on Examples 1-4, the illumination method in this embodiment adopts a distance-gated approach. Since the timing of the reflected laser pulses varies depending on the externally input target distance *d*, a high-speed shutter is used at the receiving end to receive only the laser pulses returned from the given distance. Other pulses (including backscattered light) are suppressed during imaging. After calculating the required power of the illumination laser, the optics of the emission system are adjusted to emit laser light onto the target area at the given distance according to the required full-angle laser beam divergence and target position. A split-focus plane polarization camera is used as the imaging device, completing the camera shutter opening and closing in a short time. Through high-precision delay synchronization control technology, the time delay between the laser pulse emission and the shutter opening of the gated camera is strictly controlled, ensuring that the radiation pulses reflected from the target area arrive at the camera and form an image precisely within the time of the camera's gating operation. This distinguishes the scattered light from different distances from the reflected light from the target area, improving the effective range of polarization imaging for weak targets in complex backgrounds, as well as image contrast and signal-to-noise ratio, thereby enhancing target detection and stable tracking performance.

[0053] Adjust the target to the center of the field of view, acquire the intensity maps of each linear polarization (I0°, I45°, I90°, I135°), and calculate and output the DOLP and total intensity map. The system controls the laser emission optical system to illuminate the target, then the linear polarizer rotates 360°, simultaneously calculating the average gradient of the DOLP (Difference of Pathway Per Second) in the central field of view. The polarizer rotation stops at the maximum value, and the DOLP at this point is recorded as P. max Extracting the DOLP graph P using operators max Mid-to-high frequency features (using guided filtering as the operator), such as edge and texture details, are separated into a high-frequency detail layer to achieve explicit extraction of high-frequency information, and the intensity map is then processed. As a low-frequency image, the detail layer and intensity map are linearly weighted to output an enhanced image. It can effectively improve image contrast and signal-to-noise ratio.

Claims

1. A dark and weak target enhancement device based on range-gated polarization imaging, comprising a transmitting system and a receiving system, characterized in that: the transmitting system comprises a pulsed laser, a signal modulation circuit and a transmitting optical system; the pulsed laser is used for transmitting a laser beam; the signal modulation circuit is used for generating a high-frequency modulation electrical signal to modulate the laser beam transmitted by the pulsed laser; and the transmitting optical system is used for focusing, adjusting the pointing of the light beam and the polarization state of the outgoing light; the receiving system comprises a receiving optical system, a focal plane polarization detector, a synchronous control board, a signal processing board, an image processing board and a display control device; the receiving optical system is used for imaging, image processing and adaptive system control; the focal plane polarization detector is used for collecting intensity images of linear polarizer angles in real time, and then calculating a Stokes vector representation matrix and a linear polarization degree image through the signal processing board in real time; the synchronous control board is used for realizing high-precision time delay synchronization control of laser pulse transmission and opening of the shutter of the detector; the image processing board is used for collecting polarization information, and simultaneously acquiring intensity images of four detection polarization angles (0°, 45°, 90°, 135°) in a single exposure through focal plane segmentation technology or a micro-polarization array; and the display control device is used for human-computer interaction control to realize real-time imaging display and parameter adjustment. The focal plane polarization detector is a short-wave infrared focal plane polarization imaging detector. The central wavelength of the laser beam transmitted by the pulsed laser is 1550 nm. The signal modulation circuit forms a transmission laser with high peak power, narrow pulse width and high repetition frequency after modulating the laser beam. The transmitting optical system comprises a fast mirror and a controllable linear polarizer. S is called a Stokes vector, wherein: Therefore, the linear polarization degree DOLP of arbitrary polarized light is The method comprises the following steps: Step S1. Obtain the target distance d, calculate the required power of the pulsed laser according to the target distance d, adjust the optical parameters of the transmitting system, set the laser beam divergence angle and the target position; Step S2. Generate a high-frequency modulation electrical signal through the signal modulation circuit to modulate the laser beam output by the pulsed laser, and form a transmission laser with high peak power, narrow pulse width and high repetition frequency; Step S3. Adopt a range-gated illumination mode, realize high-precision time delay synchronization control of laser pulse transmission and opening of the shutter of the detector through the synchronous control board, so that the laser pulse reflected by the target region reaches the detector and forms an image within the opening time of the shutter, and suppresses the backscattering light and other distance scattering light; 2. The dark and weak target enhancement device based on range-gated polarization imaging according to claim 1, characterized in that: Step S5. Calculate the Stokes vector representation matrix and the linear polarization degree image DOLP based on the collected intensity images through the signal processing board; 3. The dark and weak target enhancement device based on range-gated polarization imaging according to claim 1, characterized in that: In the step S7, the operator for extracting high-frequency features is a guided filter operator, which is used for extracting edge and texture detail information.

4. The dark and weak target enhancement device based on range-gated polarization imaging according to claim 1, characterized in that: ​ 5. The dark and weak target enhancement device based on range-gated polarization imaging according to claim 1, characterized in that: ​ 6. The dark and weak target enhancement device based on range-gated polarization imaging according to claim 1, characterized in that: The focal plane polarimetric detector is used for real-time acquisition of intensity images (I 0° , I 45° , I 90° , I 135° ) with linear polarizer angles of (0°, 45°, 90°, 135°), and then real-time calculation of the Stokes vector representation matrix and the degree of linear polarization (DOLP) through a signal processing board. The four parameters form a 4x1 matrix vector as follows, ​ is zero; ​ 。 7. A dark and weak target enhancement method based on range-gated polarization imaging, characterized in that: ​ ​ ​ ​ Step S4. Real-time acquisition of intensity images (I 0° , I 45° , I 90° , I 135° ) with linear polarizer angles of (0°, 45°, 90°, 135°) using a short-wave infrared focal plane array polarimetric imager. 0° , I 45° , I 90° , I 135° ) with linear polarizer angles of (0°, 45°, 90°, 135°) using a short-wave infrared focal plane array polarimetric imager. 0° , I 45° , I 90° , I 135° ) with ​ Step S6. Adjust the laser beam pointing by the fast mirror of the emission optical system so that the laser irradiates the target region, and control the controllable linear polarizer to rotate 360°, simultaneously calculate the average gradient of the linear polarization degree map of the central field of view region, stop the rotation at the position of the maximum value of the average gradient and record the polarization degree map at this time as P max ; Step S7. Extracting linear polarization degree map P by operator max Separate high-frequency detail layer from total light intensity in Stokes vector Linearly weight high-frequency detail layer and low-frequency image as low-frequency image, output enhanced image .

8. The dark and weak target enhancement method based on range-gated polarization imaging according to claim 7, characterized in that: In the step S7, the enhanced image is output wherein is a high frequency detail layer, is a weighting coefficient.

9. The dark and weak target enhancement method based on range-gated polarization imaging according to claim 7, characterized in that: ​

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