All-day laser far-field light spot testing device and use thereof

Abstract

An all-day laser far-field light spot testing device and a use thereof, relating to laser light spot measurement technologies. A photoelectric detection unit (5) detects a far-field laser echo to obtain a time distribution of an intense laser pulse, and a control unit (7) controls an exposure time of a short-wave infrared camera (3) and a detection time of the photoelectric detection unit (5), so as to better capture a pulse light spot. The short-wave infrared camera (3) performs imaging detection on a far-field light spot to obtain spatial distribution information of the light spot, a long-wave infrared camera (4) performs all-day imaging detection on a far-field background, and when the far-field background is superposed with an image of the short-wave infrared camera (3), all-day light spot image imaging can be performed. A data processing unit (6) processes a laser echo pulse waveform of the photoelectric detection unit (5) and the image of the short-wave infrared camera (3), and when necessary, fuses the image of the short-wave infrared camera (3) with the far-field background. By means of comparative analysis on a final image, all-day evaluation of a laser far-field light spot, atmospheric visibility, and target reflectivity can be achieved.

Description

All-day laser far-field spot test equipment and its application

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application claims priority to Chinese patent application No. 2024101653850, filed on February 5, 2024, entitled “All-day laser far-field spot testing equipment and its application,” which is incorporated herein by reference in its entirety. Technical Field

[0003] The present application relates to the field of laser spot measurement technology, and in particular to a full-time laser far-field spot testing device and its application. Background Art

[0004] During the development of intense pulsed lasers such as laser rangefinders, lidars, and laser light finders, it is necessary to evaluate the far-field beam quality of the laser. Generally, a near-infrared camera is used for spot imaging. The spot appears as a white, saturated circular spot in the image. The spot position is obtained through human eye observation or image processing, so that the far-field beam quality of the laser pulse can be evaluated.

[0005] When there is plenty of light during the day, clear light spot images can be obtained using infrared cameras. However, in darker environments, the near-infrared light in the background is very weak, making it difficult to image with a near-infrared camera. It is also impossible to determine the specific position of the light spot in the background, making it difficult to accurately perform light spot analysis.

[0006] Summary of the Invention

[0007] The present application provides a full-day laser far-field spot test device and its application, which is used to solve the defect in the existing technology that the spot imaging image obtained by using an infrared camera under dark light conditions cannot determine the specific position of the spot in the background, and realize full-day laser far-field spot testing.

[0008] This application provides a full-time laser far-field spot testing device, comprising:

[0009] A target, configured to receive the pulsed laser light emitted by the laser and form a far-field light spot on the target;

[0010] A short-wave infrared camera is used to perform imaging detection on the far-field light spot to obtain spatial distribution information of the far-field light spot;

[0011] A long-wave infrared camera is used for imaging and detecting the background of the far-field light spot under weak background light conditions;

[0012] a photoelectric detection unit, configured to detect the echo pulse of the far-field light spot and obtain time distribution information of the echo pulse;

[0013] a data processing unit, connected to the short-wave infrared camera, the long-wave infrared camera and the photoelectric detection unit respectively;

[0014] A control unit is connected to the data processing unit, the short-wave infrared camera and the photoelectric detection unit respectively, and is used to receive processing information from the data processing unit and control the short-wave infrared camera and the photoelectric detection unit.

[0015] According to a full-day laser far-field spot testing device provided by the present application, the control unit includes a timing controller, which is connected to the short-wave infrared camera to control the exposure time of the short-wave infrared camera; the timing controller is connected to the photoelectric detection unit to control the detection time of the photoelectric detection unit.

[0016] According to a full-day laser far-field spot testing device provided by the present application, a narrow-band filter and an attenuation plate are provided at the front end of the short-wave infrared camera lens; the control unit controls the movement of the narrow-band filter and the attenuation plate to adjust the light transmittance of the short-wave infrared camera.

[0017] According to a full-day laser far-field spot testing device provided by the present application, the photoelectric detection unit includes a photodetector and an analog-to-digital converter. The photodetector is used to detect the echo pulse waveform information of the far-field spot. The analog-to-digital converter is connected to the photodetector to convert the echo pulse waveform information detected by the photodetector into the time distribution information of the echo pulse and transmit it to the data processing unit.

[0018] According to the all-day laser far-field spot testing device provided by the present application, the all-day laser far-field spot testing device also includes a display unit, and the display unit is connected to the data processing unit.

[0019] The present application also provides a full-time laser far-field spot test method, applicable to any of the above-mentioned full-time laser far-field spot test devices, comprising:

[0020] S1. Use a long-wave infrared camera to detect the background image of the target under weak background light conditions at all times of the day and transmit it to the data processing unit;

[0021] S2, the laser emits a pulsed laser to form a far-field light spot on the target;

[0022] S3, using a photoelectric detection unit to capture the laser echo pulse diffusely reflected by the light spot on the target, and calculating the laser pulse timing information of the light spot on the target;

[0023] S4. Calculate the laser pulse timing information of the light spot on the target according to step S3, and adjust the short-wave infrared camera and the photoelectric detection unit through the control unit so that the imaging spot of the light spot on the target in the short-wave infrared camera is in the linear region of the photoelectric detection unit;

[0024] S5. Use a short-wave infrared camera to photograph the light spot on the target, obtain a far-field non-saturated light spot imaging image, and transmit it to a data processing unit;

[0025] S7. For the far-field light spot imaging image obtained by the data processing unit, if the far-field light spot imaging contour is clear and meets the processing requirements of the data processing unit, image analysis is directly performed to complete the evaluation and calculation of the far-field light spot quality; if the far-field light spot imaging contour is blurred and cannot meet the processing requirements of the data processing unit, the light spot imaging image of the short-wave infrared camera and the background imaging image of the target obtained by the long-wave infrared camera are fused and transmitted to the data processing unit, and image analysis is performed on the fused image to complete the evaluation and calculation of the far-field light spot quality.

[0026] According to a full-day laser far-field spot test method provided by the present application, in step S7, the process of fusing the spot imaging image of the short-wave infrared camera with the background imaging image of the target acquired by the long-wave infrared camera includes:

[0027] A single-stage training method is used to train the spot imaging images of the short-wave infrared camera and the background imaging images of the target acquired by the long-wave infrared camera, so that they can accurately express the features of their respective images.

[0028] A cross-spectral image fusion network framework is designed based on a densely connected network and an attention mechanism, and an encoder-decoder structure is obtained. The encoder is used to extract the feature maps of the spot imaging image of the short-wave infrared camera and the background imaging image of the target acquired by the long-wave infrared camera. After feature fusion, the fused feature maps are passed to the decoder to restore the fused image.

[0029] This application also provides a method for testing atmospheric visibility, including:

[0030] S10. Using any one of the above-mentioned all-day laser far-field spot test equipment to perform the above-mentioned all-day laser far-field spot test method under different known atmospheric visibility conditions, obtain the spot attenuation ratio under different known atmospheric visibility conditions, and form a calibration query table;

[0031] S20. Under conditions of unknown atmospheric visibility, perform the above-mentioned all-day laser far-field spot testing method using any of the above-mentioned all-day laser far-field spot testing equipment to obtain a spot attenuation ratio under the conditions of unknown atmospheric visibility;

[0032] S30. Compare the spot attenuation ratio obtained in step S20 with the calibration lookup table obtained in step S10 to obtain the atmospheric visibility corresponding to the spot attenuation ratio in step S20, and record it as the atmospheric visibility tested for the unknown atmospheric visibility.

[0033] According to a method for testing atmospheric visibility provided in this application, the light spot attenuation ratio is calculated using the following formula 1:

[0034] Where d is the light spot attenuation ratio, Δt is the camera exposure time, att is the attenuation value of the attenuation sheet added to the camera, and E(x, y, z) is the distribution of the light spot on the short-wave infrared camera image.

[0035] The present application also provides a target reflectivity testing method, applicable to any of the above-mentioned all-day laser far-field spot testing equipment, comprising:

[0036] S100. Select and replace a target in any one of the above-described all-day laser far-field spot test devices, and perform the above-described all-day laser far-field spot test method using target targets with different reflectivities, to obtain the spot attenuation ratios corresponding to the target targets with different reflectivities, and form a calibration query table;

[0037] S200, replacing the target in any one of the above-mentioned all-day laser far-field spot test devices with the reflectivity target to be measured, and then performing the above-mentioned all-day laser far-field spot test method to obtain the spot attenuation ratio after reflection from the reflectivity target to be measured;

[0038] S300, comparing the light spot attenuation ratio after reflection from the reflectivity target obtained in step S200 with the calibration lookup table obtained in step S100, and obtaining the reflectivity of the target corresponding to the light spot attenuation ratio in step S200, which is recorded as the reflectivity of the reflectivity target to be measured.

[0039] The present application provides a full-time laser far-field spot test device and its application. The device detects the far-field laser echo through a photoelectric detection unit to obtain the time distribution of the strong laser pulse. The control unit controls the exposure time of the short-wave infrared camera and the detection time of the photoelectric detection unit to better capture the pulse spot. The short-wave infrared camera performs imaging detection on the far-field spot to obtain the spatial distribution information of the spot. The long-wave infrared camera performs full-time imaging detection on the far-field background. After superimposing the image with the short-wave infrared camera, the spot image can be imaged all day long. The data processing unit processes the laser echo pulse waveform of the photoelectric detection unit, the imaging of the short-wave infrared camera, and, when necessary, fuses the imaging picture of the short-wave infrared camera with the far-field background. By comparing and analyzing the final image, it is possible to evaluate the laser's far-field spot, atmospheric visibility, and target reflectivity all day long. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] In order to more clearly illustrate the technical solutions in the present application or the prior art, a brief introduction will be given below to the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without any creative work.

[0041] FIG1 is a schematic structural diagram of a full-time laser far-field spot test device provided by the present application;

[0042] FIG2 is a schematic diagram of the fusion of the spot imaging image of the short-wave infrared camera and the background imaging image of the target acquired by the long-wave infrared camera.

[0043] Reference numerals: 1. target; 2. laser; 3. short-wave infrared camera; 4. long-wave infrared camera; 5. photoelectric detection unit; 51. photoelectric detector; 52. analog-to-digital converter; 6. data processing unit; 7. control unit; 8. display unit. DETAILED DESCRIPTION

[0044] To make the objectives, technical solutions, and advantages of this application more clear, the technical solutions in this application will be clearly and completely described below in conjunction with the accompanying drawings. Obviously, the embodiments described are only part of the embodiments of this application, not all of them. Based on the embodiments in this application, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of this application.

[0045] In the description of the embodiments of the present application, it should be noted that the terms "center", "longitudinal", "lateral", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", etc., indicating the orientation or position relationship, are based on the orientation or position relationship shown in the accompanying drawings, and are only for the convenience of describing the embodiments of the present application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the embodiments of the present application.

[0046] In the description of the embodiments of this application, it should be noted that, unless otherwise specified or limited, the terms "connected" and "connection" should be understood in a broad sense. For example, they can refer to fixed connections, detachable connections, or integral connections; they can refer to direct connections or indirect connections through an intermediary. Those skilled in the art will understand the specific meanings of the above terms in the embodiments of this application based on the specific circumstances.

[0047] In the embodiments of the present application, unless otherwise expressly specified or limited, a first feature being "above" or "below" a second feature may mean that the first and second features are in direct contact, or that the first and second features are in indirect contact through an intermediate medium. Furthermore, a first feature being "above," "above," and "above" a second feature may mean that the first feature is directly above or obliquely above the second feature, or simply means that the first feature is higher in level than the second feature. A first feature being "below," "below," and "below" a second feature may mean that the first feature is directly below or obliquely below the second feature, or simply means that the first feature is lower in level than the second feature.

[0048] In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "example", "specific example", or "some examples" means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the embodiments of the present application. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art can combine and combine different embodiments or examples described in this specification and the features of different embodiments or examples, unless they are contradictory.

[0049] The following describes the all-day laser far-field spot testing equipment and its application in conjunction with Figures 1 and 2.

[0050] One embodiment of the present application provides a full-day laser far-field spot testing device, as shown in Figure 1, including a target 1, a short-wave infrared camera 3, a long-wave infrared camera 4, a photoelectric detection unit 5, a data processing unit 6 and a control unit 7, wherein the target 1 is used to receive pulsed laser irradiation emitted by the laser 2 to form a far-field spot on the target 1; the short-wave infrared camera 3 is used to image and detect the far-field spot to obtain spatial distribution information of the far-field spot; the long-wave infrared camera 4 is used to image and detect the background of the far-field spot under weak background light conditions (the weak background light conditions involved here refer to the situation when the short-wave infrared camera 3 imaging image cannot determine the specific position of the spot in the background); the photoelectric detection unit 5 is used to detect the echo pulse of the far-field spot to obtain the time distribution information of the echo pulse; the data processing unit 6 is respectively connected to the short-wave infrared camera 3, the long-wave infrared camera 4 and the photoelectric detection unit 5; the control unit 7 is respectively connected to the data processing unit 6, the short-wave infrared camera 3 and the photoelectric detection unit 5, and is used to receive processing information from the data processing unit 6 and control the short-wave infrared camera 3 and the photoelectric detection unit 5.

[0051] It can be understood that the all-day laser far-field spot test equipment of this embodiment can be used to evaluate the far-field spot of strong pulse lasers such as laser rangefinders and lidars, as well as to measure information such as atmospheric visibility and target reflectivity. It mainly tests the spatial distribution and pulse waveform of the laser spot and performs data fusion analysis to evaluate the far-field spot, and uses variable calculations in the test process to realize the test of atmospheric visibility and target reflectivity.

[0052] Specifically, the long-wave infrared camera 4 performs all-day background imaging detection on the target 1 and transmits it to the data processing unit 6 to form an all-day background spot image. The laser 2 emits a pulsed laser to illuminate the target 1. The laser pulse forms a short-term far-field spot on the target 1 and diffusely reflects to the surroundings. The photoelectric detection unit 5 is used to capture the laser echo pulse diffusely reflected by the spot on the target 1, and calculate the laser pulse timing information of the spot on the target 1. It is used to analyze the laser pulse shape and trigger the short-wave infrared camera 3. The short-wave infrared camera 3 is triggered and exposed. The short-wave infrared camera 3 performs imaging detection on the far-field spot to obtain the spatial distribution information of the spot. The exposure time or attenuation of the short-wave infrared camera 3 is adjusted so that the imaging spot of the spot on the target 1 in the short-wave infrared camera 3 is in the linear region of the photoelectric detection unit 5, making it easier to obtain a clear spot imaging image.

[0053] During a period of sufficient light throughout the day, if the far-field spot image is clear and meets the processing requirements of the data processing unit 6, image analysis can be performed directly to complete the evaluation and calculation of the far-field spot quality. When the light is low, the background in the spot image obtained by the short-wave infrared camera 3 is very weak, making it impossible to determine the specific position of the spot in the background, nor can it be used as a reference for the spot brightness, and thus cannot meet the processing requirements of the data processing unit 6. In this case, as shown in FIG2 , the spot image of the short-wave infrared camera 3 is fused with the background image of the target 1 obtained by the long-wave infrared camera 4. The fused image is transmitted to the data processing unit 6, and image analysis is performed on the fused image to complete the evaluation and calculation of the far-field spot quality. The above process can realize the laser far-field spot test at all times of the day.

[0054] In order to improve the signal-to-noise ratio of laser pulse detection so that the short-wave infrared camera 3 does not need to operate in the saturation region, this embodiment can be achieved in two ways:

[0055] In one implementation, the control unit 7 of the all-day laser far-field spot test equipment includes a timing controller, which is connected to the short-wave infrared camera 3 to control the exposure time of the short-wave infrared camera 3; the timing controller is connected to the photoelectric detection unit 5 to control the detection time of the photoelectric detection unit 5. The short-wave infrared camera 3 is triggered to expose based on the laser pulse timing and laser pulse period detected by the photoelectric detection unit 5, thereby reducing the exposure time. Specifically, the timing controller combines the timing information of the laser pulse obtained by the photoelectric detection unit 5 with the laser frequency to calculate the next laser pulse time, forming a laser pulse trigger signal, which is used to control the exposure time of the short-wave infrared camera 3 and the detection time of the photoelectric detection unit 5, so as to better capture the pulse spot.

[0056] In another implementation, a narrowband filter and an attenuation plate are provided at the front end of the lens of the short-wave infrared camera 3 of the all-day laser far-field spot test equipment; a control unit 7 controls the movement of the narrowband filter and attenuation plate to adjust the light throughput of the short-wave infrared camera 3. In this implementation, the light pulses generally applicable to the laser 2 belong to a single wavelength band, and the control unit 7 is used to control the movement of the narrowband filter and attenuation plate to adjust the light throughput of the short-wave infrared camera 3. The narrowband filter can reduce background interference, and by increasing the attenuation of the attenuation plate, the imaging spot of the far-field light spot on the short-wave infrared camera 3 is placed in the linear region of the photoelectric detection unit 5, resulting in far-field non-saturated light spot imaging.

[0057] In some embodiments, the photodetection unit 5 includes a photodetector 51 and an analog-to-digital converter 52. The photodetector 51 is used to detect the echo pulse waveform information of the far-field light spot. The analog-to-digital converter 52 is connected to the photodetector 51 to convert the echo pulse waveform information detected by the photodetector 51 into the time distribution information of the echo pulse and transmit it to the data processing unit 6. The photodetector 51 is equipped with a high-bandwidth preamplifier circuit, a high-voltage circuit, and a signal amplification circuit. The photodetector 51 uses its high sensitivity to detect and amplify the laser echo pulse. After acquisition and conversion by the analog-to-digital converter 52, the time distribution information and timing of the intense laser pulse are obtained, which are used to analyze the laser pulse shape and trigger the short-wave infrared camera 3. The photodetector 51 can use an APD laser detector. If the test distance is short, the APD detector can also be replaced with a PIN detector. The sampling frequency of the analog-to-digital converter 52 is selected based on the laser pulse width. For example, the pulse width of a common intense pulse laser is 10ns. A GPS sampling frequency acquisition card can be selected to more completely sample the waveform and obtain the time distribution information of the intense laser pulse. The analog-to-digital converter 52 automatically sets a suitable trigger threshold and measures the laser pulse arrival time for triggering the short-wave infrared camera and testing the laser pulse frequency stability.

[0058] Specifically, we use a 1064nm DPL laser commonly used in laser rangefinders as an example. Laser 2 has a laser wavelength of 1064nm, a pulse width of approximately 10ns, and a pulse period of 20Hz. Laser 2 irradiates target 1 with laser pulses, creating a short-lived spot on target 1 that is diffusely reflected toward the surrounding area. Laser 2's duty cycle t serves as the basis for calculating the external triggering of short-wave infrared camera 3. A 1064nm narrowband filter is placed in front of the lens of short-wave infrared camera 3 to reduce background interference. Short-wave infrared camera 3 is also set to external trigger mode. When an external trigger signal arrives, short-wave infrared camera 3 initiates exposure. Long-wave infrared camera 4 also operates in external trigger mode, but its exposure time is automatically adjusted based on the ambient long-wave infrared light to achieve better background light imaging. The laser pulse is first captured by the photodetector 51 and formed into an undistorted waveform. The analog-to-digital converter 52 samples the pulse and uses an adaptive threshold to calculate the pulse arrival time t1. t1+t is the arrival time of the next pulse. The timing controller turns on the short-wave infrared camera 3 by Δt / 2 (Δt is the exposure time) in advance, allowing the complete laser pulse to be captured by the short-wave infrared camera 3 without excessive background light interference. The long-wave infrared camera 4 performs thermal imaging of the background, obtaining day and night imaging information of the background. Starting from the second pulse, the image captured by the short-wave infrared camera 3 is matched one-to-one with the pulse data collected by the analog-to-digital converter 52 and sent to the data processing unit 6 for processing.

[0059] In some embodiments, the all-day laser far-field spot test device of the present application further includes a display unit 8, which is connected to the data processing unit 6. The display unit 8 is mainly a display for displaying the processing results of the data processing unit 6. The far-field non-saturated spot imaging captured by the short-wave infrared camera 3 (or the fusion image of the short-wave infrared camera 3 and the long-wave infrared camera 4) is processed to obtain corresponding calculation templates and data for subsequent spot calculation, thereby evaluating the laser's far-field spot, atmospheric visibility, and target reflectivity.

[0060] The application of the all-day laser far-field spot test equipment provided by this application is described below. The application of each all-day laser far-field spot test equipment described below can be referenced to each other with the all-day laser far-field spot test equipment described above.

[0061] In one embodiment of the present application, a method for testing a laser far-field spot at all times is provided, comprising the following steps.

[0062] S1. Use the long-wave infrared camera 4 to perform background imaging detection on the target 1 under weak background light conditions throughout the day and transmit the background imaging to the data processing unit.

[0063] S2. Laser 2 emits a pulsed laser to illuminate the target 1 to form a far-field light spot.

[0064] S3. Utilize the photoelectric detection unit 5 to capture the laser echo pulse diffusely reflected by the light spot on the target 1 and calculate the laser pulse timing information of the light spot on the target 1.

[0065] S4. Calculate the laser pulse timing information of the light spot on the target 1 according to step S3, and adjust the short-wave infrared camera 3 and the photoelectric detection unit 5 through the control unit 7 so that the imaging spot of the light spot on the target 1 in the short-wave infrared camera 3 is in the linear region of the photoelectric detection unit 5.

[0066] S5 , using the short-wave infrared camera 3 to photograph the light spot on the target 1 , obtaining a far-field non-saturated light spot imaging image, and transmitting the image to the data processing unit 6 .

[0067] S7. For the far-field spot imaging image acquired by the data processing unit 6, if the far-field spot imaging contour is clear and meets the processing requirements of the data processing unit 6, image analysis is directly performed to complete the evaluation and calculation of the far-field spot quality; if the far-field spot imaging contour is blurred and cannot meet the processing requirements of the data processing unit 6, the spot imaging image of the short-wave infrared camera 3 is fused with the background imaging image of the target 1 acquired by the long-wave infrared camera 4, and the fused image is transmitted to the data processing unit 6, and image analysis is performed on the fused image to complete the evaluation and calculation of the far-field spot quality.

[0068] It is understood that when conducting all-day laser far-field spot testing, atmospheric visibility is good, generally greater than 10 km, and the target 1 is flat and has a uniform reflectivity. The photoelectric detection unit 5 is used to detect the far-field laser echo and obtain the time distribution information of the strong laser pulse. The control unit 7 is used to control the exposure time of the short-wave infrared camera 3 and the detection time of the photoelectric detection unit 5 to better capture the pulse spot. The short-wave infrared camera 3 is used to image and detect the far-field spot and obtain the spatial distribution information of the spot. The long-wave infrared camera 4 is used to image and detect the far-field background all-day. After superimposing the image with the short-wave infrared camera 3, the spot image can be imaged all day. The data processing unit 6 processes the laser echo pulse waveform information of the photoelectric detection unit 5, the image image of the short-wave infrared camera 3, and, if necessary, fuses the image image of the short-wave infrared camera 3 with the far-field background. By comparing and analyzing the final image, the laser far-field spot, atmospheric visibility, and target reflectivity are evaluated.

[0069] Among them, in step S7, the process of fusing the spot imaging image of the short-wave infrared camera 3 with the background imaging image of the target 1 obtained by the long-wave infrared camera 4 includes: using a single-stage training method to train the spot imaging image of the short-wave infrared camera 3 and the background imaging image of the target 1 obtained by the long-wave infrared camera 4, so that they can accurately express the features of their respective images; designing a cross-spectral image fusion network framework based on a densely connected network and an attention mechanism to obtain an encoder-decoder structure, using the encoder to extract feature maps of the spot imaging image of the short-wave infrared camera 3 and the background imaging image of the target 1 obtained by the long-wave infrared camera 4, and after feature fusion, passing the fused feature map into the decoder to restore the fused image.

[0070] During the network training phase, a single-stage training method is used to train the shortwave channel of shortwave infrared camera 3 and the longwave channel of longwave infrared camera 4 separately. The goal is to ensure that both channels can accurately represent the features of images in their respective bands. The fusion of shortwave infrared and longwave infrared images is essentially the fusion of infrared images of different bands. This type of image fusion aims to preserve the effective information of different bands while eliminating redundant information. This method highlights key objects in the fused image while preserving the rich texture details of the original images as much as possible.

[0071] The images from the short-wave infrared camera 3 and the images from the long-wave infrared camera 4 are fused using a deep learning-based method and a neural network algorithm to achieve the purpose of highlighting the imaging effect of the laser spot against the background. During the image fusion process, a cross-spectral image fusion network framework, DAFNet, is designed based on a densely connected network and an attention mechanism. This network framework uses an encoder-decoder structure. The encoder is used to extract feature maps from each band. After feature fusion, the fused feature maps are passed to the decoder to restore the fused image. Unlike directly connected convolutional neural networks, the densely connected block uses a feature map sharing method, which can enhance shallow feature transfer while reducing the number of parameters. The attention block can make the image features of each band in the extracted feature map more prominent, allowing the network to focus more on effective features. In addition, skip connections can be added when designing the network framework to transfer shallow features to the decoder, which can effectively enhance the feature expression of the fused image.

[0072] The sum of pixel loss and structural similarity (SSIM) loss is used as the total loss function. These two loss functions can constrain the reconstructed pixel error and edge error at the same time. The total loss function can be expressed as: F loss =αP loss +βSSIM loss ,

[0073] Among them, α and β are adjustable parameters. In the current experiment, they are both 0.5, indicating that the two loss functions have the same weight in the total loss.

[0074] P loss The calculation method is: P loss =‖OI‖2,

[0075] SSIM loss The calculation method is: SSIM loss =1-SSIM(O,I),

[0076] Where O represents the output image matrix and I represents the input image matrix.

[0077] The data processing unit 6 also integrates and analyzes the sampled data from the photoelectric detection unit 5 and the test data from the short-wave infrared camera 3 to generate dynamic laser spot information. This allows observation of the temporal distribution of the spot intensity during pulsed irradiation, overcoming the loss of time-domain information due to integration in the infrared camera. Furthermore, the data processing unit 6 can output the position of the laser spot, thereby assessing the pointing error of the laser irradiation.

[0078] Another application embodiment of the present application provides a method for testing atmospheric visibility, including the following steps.

[0079] S10. Use any of the above-mentioned all-day laser far-field spot test equipment to perform the above-mentioned all-day laser far-field spot test method under different known atmospheric visibility conditions to obtain the spot attenuation ratio under different known atmospheric visibility conditions and form a calibration query table.

[0080] S20. Under conditions of unknown atmospheric visibility, use any one of the above-mentioned all-day laser far-field spot testing equipment to perform the above-mentioned all-day laser far-field spot testing method to obtain the spot attenuation ratio under conditions of unknown atmospheric visibility.

[0081] S30. Compare the spot attenuation ratio obtained in step S20 with the calibration lookup table obtained in step S10 to obtain the atmospheric visibility corresponding to the spot attenuation ratio in step S20, and record it as the atmospheric visibility tested for the unknown atmospheric visibility.

[0082] It is understood that when testing atmospheric visibility, the beam quality of the laser 2 used is known, the target 1 is flat and has a uniform reflectivity, and the short-wave infrared camera 3 is used to obtain the spot attenuation ratio of the light spot to reflect the atmospheric visibility. The atmospheric visibility and spot attenuation ratio are calibrated to form a lookup table. The data processing unit 6 calculates the pulse amplitude and echo energy of the echo pulse data from the photoelectric detection unit 5, and the visibility can be calculated using the radar equation.

[0083] Similarly, by comparing the image captured by the short-wave infrared camera 3 with the previous test spot data, the spatial transient changes in atmospheric visibility can also be obtained. The attenuation ratio of atmospheric visibility is calculated using the following formula, and the atmospheric visibility is obtained by looking up the table.

[0084] The spot attenuation ratio is calculated using the following formula 1:

[0085] Where d is the light spot attenuation ratio, Δt is the camera exposure time, att is the attenuation value of the attenuation plate added to the camera, and E(x, y, z) is the distribution of the light spot on the short-wave infrared camera image.

[0086] Another application embodiment of the present application provides a method for testing target reflectivity, including the following steps.

[0087] S100. Select and replace the target target 1 in any of the above-mentioned all-day laser far-field spot test equipment, and use target targets 1 with different reflectivities to perform the above-mentioned all-day laser far-field spot test method respectively, to obtain the spot attenuation ratio corresponding to the target targets 1 with different reflectivities, and form a calibration query table.

[0088] S200. Replace the target 1 in any of the above-mentioned all-day laser far-field spot test equipment with the reflectivity target to be measured, and then use the above-mentioned all-day laser far-field spot test method to obtain the spot attenuation ratio after reflection from the reflectivity target to be measured.

[0089] S300, comparing the light spot attenuation ratio after reflection of the reflectivity target to be measured obtained in step S200 with the calibration lookup table obtained in step S100, and obtaining the reflectivity of target 1 corresponding to the light spot attenuation ratio in step S200, which is recorded as the reflectivity of the reflectivity target to be measured.

[0090] It is understood that during target visibility testing, the beam quality of laser 2 is known, and atmospheric visibility is good, typically greater than 10 km. Shortwave infrared camera 3 is used to obtain the spot attenuation ratio of the light spot, reflecting the reflectivity. The target reflectivity and spot attenuation ratio can be calibrated in advance to form a lookup table.

[0091] The laser spot and laser echo waveforms are modulated by the target's shape and reflectivity, causing them to distort. By comparing the waveforms before and after distortion, the target's reflectivity can be inversely calculated. The spot attenuation ratio is calculated using the same formula as above. After calculating the spot attenuation ratio d, the target reflectivity value is obtained by looking up the table.

[0092] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present application, rather than to limit them. Although the present application has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. These modifications or replacements do not deviate the essence of the corresponding technical solutions from the scope of the technical solutions of the embodiments of the present application.

Claims

1. A full-time laser far-field spot test device, comprising: A target (1) is used to receive pulsed laser irradiation emitted by a laser (2) to form a far-field light spot on the target (1); A short-wave infrared camera (3) is used to perform imaging detection on the far-field light spot to obtain spatial distribution information of the far-field light spot; A long-wave infrared camera (4) is used for imaging and detecting the background of the far-field light spot under weak background light conditions; A photoelectric detection unit (5) is used to detect the echo pulse of the far-field light spot and obtain time distribution information of the echo pulse; a data processing unit (6), connected to the short-wave infrared camera (3), the long-wave infrared camera (4) and the photoelectric detection unit (5); A control unit (7) is connected to the data processing unit (6), the short-wave infrared camera (3) and the photoelectric detection unit (5) respectively, and is used to receive processing information from the data processing unit (6) and control the short-wave infrared camera (3) and the photoelectric detection unit (5).

2. The all-day laser far-field spot test equipment according to claim 1, wherein: The control unit (7) comprises a timing controller, the timing controller being connected to the short-wave infrared camera (3) to control the exposure time of the short-wave infrared camera (3); and the timing controller being connected to the photoelectric detection unit (5) to control the detection time of the photoelectric detection unit (5).

3. The all-day laser far-field spot test equipment according to claim 1, wherein: A narrowband filter and an attenuation plate are provided at the front end of the lens of the short-wave infrared camera (3); and the control unit (7) controls the movement of the narrowband filter and the attenuation plate to adjust the light transmission amount of the short-wave infrared camera (3).

4. The all-day laser far-field spot test equipment according to claim 1, wherein: The photoelectric detection unit (5) includes a photoelectric detector (51) and an analog-to-digital converter (52), the photodetector (51) is used to detect the echo pulse waveform information of the far-field light spot, and the analog-to-digital converter (52) is connected to the photodetector (51) to convert the echo pulse waveform information detected by the photodetector (51) into time distribution information of the echo pulse and transmit it to the data processing unit (6).

5. The all-day laser far-field spot test equipment according to any one of claims 1 to 4, characterized in that: The all-day laser far-field spot testing device further comprises a display unit (8), and the display unit (8) is connected to the data processing unit (6).

6. A method for testing a laser far-field spot around the clock, applicable to the laser far-field spot testing device as claimed in any one of claims 1 to 5, comprising: S1, using a long-wave infrared camera (4) to detect background imaging of a target (1) under weak background light conditions at all times of the day and transmit the imaging to a data processing unit (6); S2, the laser (2) emits a pulsed laser to irradiate the target (1) to form a far-field light spot; S3, using the photoelectric detection unit (5) to capture the laser echo pulse diffusely reflected by the light spot on the target (1), and calculating the laser pulse timing information of the light spot on the target (1); S4, calculating the laser pulse timing information of the light spot on the target (1) according to step S3, and adjusting the short-wave infrared camera (3) and the photoelectric detection unit (5) through the control unit (7) so that the imaging light spot of the light spot on the target (1) in the short-wave infrared camera (3) is in the linear region of the photoelectric detection unit (5); S5, using a short-wave infrared camera (3) to photograph the light spot on the target (1), obtaining a far-field non-saturated light spot imaging image, and transmitting the image to a data processing unit (6); S7. For the far-field light spot imaging image acquired by the data processing unit (6), if the far-field light spot imaging contour is clear and meets the processing requirements of the data processing unit (6), image analysis is directly performed to complete the evaluation calculation of the far-field light spot quality; if the far-field light spot imaging contour is fuzzy and cannot meet the processing requirements of the data processing unit (6), the light spot imaging image of the short-wave infrared camera (3) and the background imaging image of the target (1) acquired by the long-wave infrared camera (4) are fused and transmitted to the data processing unit (6), and image analysis is performed on the fused image to complete the evaluation calculation of the far-field light spot quality.

7. The all-day laser far-field spot testing method according to claim 6, wherein: In step S7, the process of fusing the spot imaging image of the short-wave infrared camera (3) with the background imaging image of the target (1) acquired by the long-wave infrared camera (4) includes: A single-stage training method is used to train the spot imaging image of the short-wave infrared camera (3) and the background imaging image of the target (1) obtained by the long-wave infrared camera (4), so that the image can accurately express the characteristics of each image; A cross-spectral image fusion network framework is designed based on a densely connected network and an attention mechanism to obtain an encoder-decoder structure. The encoder is used to extract the feature maps of the spot imaging image of the short-wave infrared camera (3) and the background imaging image of the target (1) obtained by the long-wave infrared camera (4). After feature fusion, the fused feature maps are passed to the decoder to restore the fused image.

8. A method for testing atmospheric visibility, comprising: S10. Using the all-day laser far-field spot test equipment according to any one of claims 1 to 5, perform the all-day laser far-field spot test method according to claim 6 under different known atmospheric visibility conditions, obtain the spot attenuation ratio under different known atmospheric visibility conditions, and form a calibration query table; S20. Under conditions of unknown atmospheric visibility, use the all-day laser far-field spot test device according to any one of claims 1 to 5 to perform the all-day laser far-field spot test method according to claim 6 to obtain a spot attenuation ratio under conditions of unknown atmospheric visibility; S30. Compare the spot attenuation ratio obtained in step S20 with the calibration lookup table obtained in step S10 to obtain the atmospheric visibility corresponding to the spot attenuation ratio in step S20, and record it as the atmospheric visibility tested for the unknown atmospheric visibility.

9. The atmospheric visibility testing method according to claim 8, characterized in that: The light spot attenuation ratio is calculated by the following formula: Where d is the light spot attenuation ratio, Δt is the camera exposure time, att is the attenuation value of the attenuation sheet added to the camera, and E(x, y, z) is the distribution of the light spot on the short-wave infrared camera image.

10. A target reflectivity testing method, applicable to the all-day laser far-field spot testing device according to any one of claims 1 to 5, comprising: S100. Select and replace the target (1) in the all-day laser far-field spot test equipment according to any one of claims 1 to 5, and respectively perform the all-day laser far-field spot test method according to claim 6 using target targets (1) with different reflectivities, obtain the spot attenuation ratios corresponding to the target targets (1) with different reflectivities, and form a calibration query table; S200, replacing the target (1) in the all-day laser far-field spot test device described in any one of claims 1 to 5 with the reflectivity target to be measured, and then performing the all-day laser far-field spot test method described in claim 6 to obtain the spot attenuation ratio after reflection from the reflectivity target to be measured; S300, comparing the light spot attenuation ratio after reflection from the reflectivity target to be measured obtained in step S200 with the calibration query table obtained in step S100, and obtaining the reflectivity of the target (1) corresponding to the light spot attenuation ratio in step S200, which is recorded as the reflectivity of the reflectivity target to be measured.

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