Laser semi-active guidance system anti-interference method based on focal plane polarization imaging

Abstract

According to the laser semi-active guidance system anti-interference method based on focal plane polarization imaging, linear polarization parameters in four directions are processed, a polarization degree image and an intensity image are fused, a target guidance image is obtained, a target signal is highlighted from an interference signal, and the anti-interference performance of the laser semi-active guidance system is improved. And the anti-interference capability of the laser semi-active guidance system is effectively improved. According to the method, resolution reduction is carried out on the down-sampled polarization image, signal features are reserved as much as possible, and good data support is provided for subsequent data processing. As the detection system is based on the focal plane polarization imaging detector, on one hand, the detection signal-to-noise ratio can be improved, and on the other hand, the interference signal strength can be reduced, so that the probability of saturation of the seeker detector caused by interference laser can be reduced under the condition of ensuring the quality of a guidance signal.

Description

Technical Field

[0001] The invention relates to the field of imaging technology, and in particular to an anti-interference method for a laser semi-active guidance system based on split-focus plane polarization imaging. Background Art

[0002] Laser semi-active guidance achieves target detection and positioning by actively emitting a pointer laser. However, the pointer laser is easily detected by the other party, which drives its jamming system to emit jamming laser to the seeker. Therefore, it is crucial to improve the anti-jamming capability of the laser semi-active guidance system.

[0003] Ning Ming et al. proposed a long-distance laser semi-active azimuth measurement device based on polarization detection, which improved the signal-to-noise ratio of the laser semi-active positioning system, improved the angle measurement accuracy through Kalman filtering, and realized the function of the laser semi-active positioning system to correctly solve the target azimuth information in the case of a crescent-shaped spot. Lu Qi et al. proposed a polarization spectrum integration method suitable for the seeker, using the characteristics of multiple imaging of the microlens array to achieve fast and efficient acquisition of the target polarization spectrum information, and compared the imaging effects of visible light imaging, polarization imaging, spectral imaging and polarization spectrum imaging. The contrast of the target was increased by 97% by using multi-dimensional imaging. Most of the existing methods are aimed at the influence of complex background environment and climate factors on the guidance performance of optical seekers, and study the angle of improving the target detection and positioning accuracy. These methods have the following problems: First, there is insufficient research on how to improve the anti-interference ability of the laser semi-active guidance system when there is an interfering laser. Second, the difference between the polarization characteristics of the target reflected laser and the interfering laser polarization characteristics is not fully explored. In short, the existing methods cannot fully explore the difference in polarization characteristics between the interfering laser and the target emitted laser, and cannot effectively extract the guidance signal from the interfering laser. Summary of the invention

[0004] The present invention proposes an anti-interference method for a laser semi-active guidance system based on split-focus plane polarization imaging, which can at least solve one of the technical problems in the background technology.

[0005] To achieve the above object, the present invention adopts the following technical solutions: A laser semi-active guidance system anti-interference method based on split-focus plane polarization imaging comprises the following steps: Step 1: down-sample the composite image collected by the focal plane polarization imaging detector into images in four polarization directions according to the polarization directions (0°, 45°, 90° and 135°).

[0006] Step 2: After downsampling, the lateral and longitudinal resolutions of the image become half of the original image, and the bilinear interpolation algorithm is used to restore the resolution of the image with single-direction polarization.

[0007] Step 3: Use the polarization images in four directions to calculate the Stokes parameters of the target pixel by pixel S 0, S 1, S 2.

[0008] Step 4: Use the Stokes parameter of each pixel to solve the polarization degree of each pixel and obtain the polarization degree image in the orthogonal direction.

[0009] Step 5: Take the minimum value of the intensity in the four polarization directions pixel by pixel to obtain the minimum polarization angle intensity image.

[0010] Step 6: Get the total confidence image C and normalize C: Step 7: According to the pixel Compute composite intensity image I Step 8: Use the normalized total confidence image and the synthetic intensity image to obtain an image that can be used for guidance 。

[0011] Furthermore, the step 1 comprises: A split-focus plane polarization imaging detector is used to collect a single pixel M × N Image, define the coordinate coefficients:

[0012] According to the coordinates (1+i, 1+j), (1+i, 1+j), (1+i, 1+j), (1+i, 1+j), the original image is downsampled into images in four polarization directions (0°, 45°, 90°, and 135°).

[0013] Furthermore, the step 2 includes: The restored image integer coordinates ( X , Y ) is mapped to single polarization direction image coordinates ( X scr , Y scr )

[0014] The single polarization direction image is placed in ( X scr , Y scr ) near four integer coordinate points ( X scr +Δ X , Y scr +Δ Y ), Xscr +Δ X , Y scr -1+Δ Y ), X scr -1+Δ X , Y scr +Δ Y ), X scr -1+Δ X , Y scr -1+Δ Y ) f ( X scr +Δ X , Y scr +Δ Y ), f ( X scr +Δ X , Y scr -1+Δ Y ), f ( X scr -1+Δ X , Y scr +Δ Y ), f ( X scr -1+Δ X , Y scr -1+Δ Y ) into the following formula to calculate the pixel value at the image coordinate point (X, Y) after restoring the resolution: .

[0015] Furthermore, the step three comprises: Using polarization images in four directions, the Stokes parameters of the target are calculated pixel by pixel. S 0, S 1, S 2:

[0016] in I 0, I 90 , I 45 , I 135They are the light intensity signals of the four polarization directions of each pixel.

[0017] Furthermore, the step 4 includes: Using the Stokes parameters of each pixel, the polarization degree of each pixel is solved DoLP :

[0018] Calculate the polarization degree in the orthogonal direction pixel by pixel, calculate the ratio of the non-polarized part of the signal light to the total light intensity, and obtain the non-polarized positive degree confidence image C Dolp : .

[0019] Furthermore, the step five comprises: Take the minimum value of the intensity in the four polarization directions pixel by pixel to obtain the image C m : ; Furthermore, the step six comprises: Get the total confidence image C

[0020] Normalize C:

[0021] Furthermore, the step seven comprises: According to each pixel Calculate the composite intensity image I

[0022] Furthermore, the step eight comprises: Obtain an image C that can be used for guidance G .

[0023] On the other hand, the present invention further discloses a computer-readable storage medium storing a computer program, wherein when the computer program is executed by a processor, the processor executes the steps of the above method.

[0024] On the other hand, the present invention further discloses a computer device, including a memory and a processor, wherein the memory stores a computer program, and when the computer program is executed by the processor, the processor executes the steps of the above method.

[0025] In summary, since the surface of the indicated target is relatively rough and has a good depolarization effect, the signal polarization degree of the seeker detector is reduced. The linearly polarized light emitted by the interference system directly reaches the detector. Therefore, the guidance signal and the interference signal can be distinguished by the polarization characteristics of the received signal, and the interference signal can be further suppressed to retain the guidance signal. The present invention processes the linear polarization parameters in four directions, fuses the polarization degree image and the intensity image, obtains the target guidance image, highlights the target signal from the interference signal, and effectively improves the anti-interference ability of the laser semi-active guidance system.

[0026] The present invention restores the resolution of the downsampled polarization image, retains the signal characteristics as much as possible, and provides good data support for subsequent data processing.

[0027] Since the detection system of the present invention is based on a split-focus plane polarization imaging detector, it can improve the detection signal-to-noise ratio on the one hand, and reduce the interference signal strength on the other hand. Therefore, the probability of the interference laser causing the saturation of the seeker detector can be reduced while ensuring the quality of the guidance signal. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 It is a flowchart of the present invention. DETAILED DESCRIPTION

[0029] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments.

[0030] like Figure 1 As shown, the anti-interference method of the laser semi-active guidance system based on split-focus plane polarization imaging described in this embodiment includes the following steps: Step 1: down-sample the composite image collected by the focal plane polarization imaging detector into images in four polarization directions according to the polarization directions (0°, 45°, 90° and 135°).

[0031] Step 2: After downsampling, the lateral and longitudinal resolutions of the image become half of the original image, and the bilinear interpolation algorithm is used to restore the resolution of the image with single-direction polarization.

[0032] Step 3: Use the polarization images in four directions to calculate the Stokes parameters of the target pixel by pixel S 0, S 1, S 2.

[0033] Step 4: Use the Stokes parameter of each pixel to solve the polarization degree of each pixel and obtain the polarization degree image in the orthogonal direction.

[0034] Step 5: Take the minimum value of the intensity in the four polarization directions pixel by pixel to obtain the minimum polarization angle intensity image.

[0035] Step 6: Get the total confidence image C and normalize C: Step 7: According to the pixel Compute composite intensity image I Step 8: Use the normalized total confidence image and the synthetic intensity image to obtain an image that can be used for guidance 。

[0036] Specifically, the step one includes: A split-focus plane polarization imaging detector is used to collect a single pixel M × N Image, define the coordinate coefficients:

[0037] According to the coordinates (1+i, 1+j), (1+i, 1+j), (1+i, 1+j), (1+i, 1+j), the original image is downsampled into images in four polarization directions (0°, 45°, 90°, and 135°).

[0038] The second step comprises: The restored image integer coordinates ( X , Y ) is mapped to single polarization direction image coordinates ( X scr , Y scr )

[0039] The single polarization direction image is placed in ( X scr , Y scr ) near four integer coordinate points ( X scr +Δ X , Y scr +Δ Y ), X scr +Δ X , Y scr -1+Δ Y ), X scr -1+Δ X , Y scr +Δ Y ),X scr -1+Δ X , Y scr -1+Δ Y ) f ( X scr +Δ X , Y scr +Δ Y ), f ( X scr +Δ X , Y scr -1+Δ Y ), f ( X scr -1+Δ X , Y scr +Δ Y ), f ( X scr -1+Δ X , Y scr -1+Δ Y ) into the following formula to calculate the pixel value at the image coordinate point (X, Y) after restoring the resolution:

[0040] The step three comprises: Using polarization images in four directions, the Stokes parameters of the target are calculated pixel by pixel. S 0, S 1, S 2:

[0041] in I 0, I 90 , I 45 , I 135 They are the light intensity signals of the four polarization directions of each pixel.

[0042] The fourth step comprises: Using the Stokes parameters of each pixel, the polarization degree of each pixel is solved DoLP :

[0043] Calculate the polarization degree in the orthogonal direction pixel by pixel, calculate the ratio of the non-polarized part of the signal light to the total light intensity, and obtain the non-polarized positive degree confidence image C Dolp :

[0044] The step five comprises: Take the minimum value of the intensity in the four polarization directions pixel by pixel to obtain the image C m :

[0045] The step six comprises: Get the total confidence image C

[0046] Normalize C:

[0047] The step seven comprises: According to each pixel Calculate the composite intensity image I

[0048] The step eight comprises: Obtain an image C that can be used for guidance G .

[0049] In summary, the present invention can be used for a semi-active laser terminal guidance system. The system uses a linearly polarized light laser source as an indicator light signal, which is received by the focal plane polarization detector of the seeker after being reflected by the target. When directly irradiated by an interfering laser, the method of the present invention can be used to distinguish between guidance signals and interference signals. The image obtained by the focal plane is now downsampled into images in four polarization directions. Since the focal plane detector is an array structure, the resolution of the downsampled image is half of the original image in both horizontal and vertical directions. Therefore, a bilinear interpolation algorithm is used to restore the image resolution. The Stokes parameters of the four polarization direction images with restored resolution are calculated through four intensity signals. The Stokes parameters can be used to calculate information such as the degree of polarization and polarization angle of the target. The target degree of polarization is calculated, and the signal of the non-biased component is retained. The intensity signals of the four polarization directions are compared, and the minimum intensity signal image is taken. The non-biased signal image and the minimum polarization intensity signal image are fused and normalized to obtain a normalized polarization image. According to the intensity signal in the combined direction, a synthetic intensity image is calculated. The synthetic intensity image and the normalized polarization image are fused to obtain the final guidance image.

[0050] On the other hand, the present invention further discloses a computer-readable storage medium storing a computer program, wherein when the computer program is executed by a processor, the processor executes the steps of the above method.

[0051] On the other hand, the present invention further discloses a computer device, including a memory and a processor, wherein the memory stores a computer program, and when the computer program is executed by the processor, the processor executes the steps of the above method.

[0052] In another embodiment provided in the present application, a computer program product comprising instructions is also provided, which, when executed on a computer, enables the computer to execute any of the anti-interference methods for a laser semi-active guidance system based on split-focal plane polarization imaging in the above-mentioned embodiments.

[0053] It is understandable that the system, device and storage medium provided in the embodiments of the present invention correspond to the method provided in the embodiments of the present invention, and the explanation, examples and beneficial effects of the relevant contents can refer to the corresponding parts in the above methods.

[0054] In the above embodiments, it can be implemented in whole or in part by software, hardware, firmware or any combination thereof. When implemented using software, it can be implemented in whole or in part in the form of a computer program product. The computer program product includes one or more computer instructions. When the computer program instructions are loaded and executed on a computer, the process or function described in the embodiment of the present application is generated in whole or in part. The computer may be a general-purpose computer, a special-purpose computer, a computer network, or other programmable device. The computer instructions may be stored in a computer-readable storage medium, or transmitted from one computer-readable storage medium to another computer-readable storage medium. For example, the computer instructions may be transmitted from a website site, a computer, a server or a data center by wired (e.g., coaxial cable, optical fiber, digital subscriber line (DSL)) or wireless (e.g., infrared, wireless, microwave, etc.) mode to another website site, computer, server or data center. The computer-readable storage medium may be any available medium that a computer can access or a data storage device such as a server or a data center that includes one or more available media integrated. The available medium may be a magnetic medium (e.g., a floppy disk, a hard disk, a tape), an optical medium (e.g., a DVD), or a semiconductor medium (e.g., a solid-state drive Solid State Disk (SSD)), etc.

[0055] It should be noted that, in this article, relational terms such as first and second, etc. are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "include", "comprise" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device. In the absence of further restrictions, the elements defined by the sentence "comprise a ..." do not exclude the existence of other identical elements in the process, method, article or device including the elements.

[0056] Each embodiment in this specification is described in a related manner, and the same or similar parts between the embodiments can be referred to each other, and each embodiment focuses on the differences from other embodiments. In particular, for the system embodiment, since it is basically similar to the method embodiment, the description is relatively simple, and the relevant parts can be referred to the partial description of the method embodiment.

[0057] The above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit the same. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that the technical solutions described in the aforementioned embodiments may still be modified, or some of the technical features may be replaced by equivalents. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A laser semi-active guidance system anti-interference method based on split-focus plane polarization imaging, characterized in that: The following steps are involved: Step 1, down-sampling the composite image collected by the focal plane polarization imaging detector into images in four polarization directions according to polarization directions of 0°, 45°, 90° and 135°; Step 2: After downsampling, the horizontal and vertical resolutions of the image become half of the original image, and a bilinear interpolation algorithm is used to restore the resolution of the single-direction polarization image; Step 3: Use the polarization images in four directions to calculate the Stokes parameters of the target pixel by pixel S 0, S 1, S 2; Step 4: Using the Stokes parameter of each pixel, solve the polarization degree of each pixel and obtain the polarization degree image in the orthogonal direction; Step 5: Take the minimum value of the intensity in the four polarization directions pixel by pixel to obtain the minimum polarization angle intensity image; Step 6: Obtain the total confidence image C and perform normalization on C; Step 7: According to the pixel Compute composite intensity image I ; Step 8: Use the normalized total confidence image and the synthetic intensity image to obtain an image that can be used for guidance 。 2. The anti-interference method of the laser semi-active guidance system based on split-focus plane polarization imaging according to claim 1 is characterized in that: The step one comprises: A split-focal plane polarization imaging detector is used to collect a single pixel M × N Image, define the coordinate coefficients: According to the coordinates (1+i, 1+j), (1+i, 1+j), (1+i, 1+j), (1+i, 1+j), the original image is downsampled into images in four polarization directions: 0°, 45°, 90°, and 135°.

3. The anti-interference method of the laser semi-active guidance system based on split-focus plane polarization imaging according to claim 2 is characterized in that: The second step comprises: The restored image integer coordinates ( X , Y ) is mapped to single polarization direction image coordinates ( X scr , Y scr ) The single polarization direction image is placed in ( X scr , Y scr ) near four integer coordinate points ( X scr +Δ X , Y scr +Δ Y ), X scr +Δ X , Y scr -1+Δ Y ), X scr -1+Δ X , Y scr +Δ Y ), X scr -1+Δ X , Y scr -1+Δ Y ) f ( X scr +Δ X , Y scr +Δ Y ), f ( X scr +Δ X , Y scr -1+Δ Y ), f ( X scr -1+Δ X , Y scr +Δ Y ), f ( X scr -1+Δ X , Y scr -1+Δ Y ) into the following formula to calculate the pixel value at the image coordinate point (X, Y) after restoring the resolution: 。 4. The anti-interference method of the laser semi-active guidance system based on split-focus plane polarization imaging according to claim 3 is characterized in that: The step three comprises: Using polarization images in four directions, the Stokes parameters of the target are calculated pixel by pixel. S 0, S 1, S 2: in I 0, I 90 , I 45 , I 135 They are the light intensity signals of the four polarization directions of each pixel.

5. The anti-interference method of the laser semi-active guidance system based on split-focus plane polarization imaging according to claim 4 is characterized in that: The fourth step comprises: Using the Stokes parameters of each pixel, the polarization degree of each pixel is solved DoLP : Calculate the polarization degree in the orthogonal direction pixel by pixel, calculate the ratio of the non-polarized part of the signal light to the total light intensity, and obtain the non-polarized positive degree confidence image C Dolp : 。 6. The anti-interference method of the laser semi-active guidance system based on split-focus plane polarization imaging according to claim 5 is characterized in that: The step five comprises: Take the minimum value of the intensity in the four polarization directions pixel by pixel to obtain the image C m : 。 7. The anti-interference method of the laser semi-active guidance system based on split-focus plane polarization imaging according to claim 6 is characterized in that: The step six comprises: Get the total confidence image C Normalize C: 。 8. The anti-interference method of the laser semi-active guidance system based on split-focus plane polarization imaging according to claim 7 is characterized in that: The step seven comprises: According to each pixel Calculate the composite intensity image I 。 9. The anti-interference method of the laser semi-active guidance system based on split-focus plane polarization imaging according to claim 8, characterized in that: The step eight comprises: Get an image C that can be used for guidance G 。

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