Apparatus and method for testing far-field beam quality of laser device

Abstract

An apparatus and method for testing the far-field beam quality of a laser device. The apparatus comprises a target (1), a laser device (2), a four-quadrant photodetection unit (4), a near-infrared camera (5), a data processing unit (6), and a control unit; the laser device (2) is arranged on a two-dimensional turntable (3), and pulse laser emitted by the laser device (2) irradiates the target (1); the four-quadrant photodetection unit (4) receives a laser echo pulse diffusely reflected by a light spot on the target (1); the near-infrared camera (5) images the light spot formed on the target (1); the data processing unit (6) is connected to the four-quadrant photodetection unit (4) and the near-infrared camera (5); and the control unit is connected to the data processing unit (6), and is used for controlling the two-dimensional turntable (3) and controlling the near-infrared camera (5). Light spot position information is acquired by means of the four-quadrant photodetection unit (4), the orientation of the laser device (2) is adjusted, and the four-quadrant photodetection unit (4) and the near-infrared camera (5) are cooperatively used, thereby accurately acquiring a far-field unsaturated light spot of a far-field light spot, and performing quality evaluation on the far-field unsaturated light spot.

Description

Laser far-field beam quality testing device and testing method

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application claims priority to Chinese patent application No. 2024101653795, filed on February 5, 2024, entitled “Laser far-field beam quality testing device and testing method,” which is incorporated herein by reference in its entirety. Technical Field

[0003] The present application relates to the technical field of laser spot measurement, and in particular to a laser far-field beam quality testing device and testing method. 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] In far-field beam quality testing, the background is relatively complex, and the light spot is imaged as a white saturated circular spot in the image. However, there may be more white saturated circular spots in a complex background, and the tester's judgment results or image processing results may be incorrect, or it may be difficult to find the light spot position.

[0006] Therefore, when existing near-infrared intense pulse laser far-field beam quality testing equipment tests the far-field beam quality, it may be affected by the background and make it difficult to find the light spot, which limits the usage scenarios and effects.

[0007] Summary of the Invention

[0008] The present application provides a laser far-field beam quality testing device and testing method, which are used to solve the defect in the prior art that the far-field beam quality may be affected by the background and it is difficult to find the light spot when testing the far-field beam quality.

[0009] The present application provides a laser far-field beam quality testing device, comprising:

[0010] target;

[0011] A laser is arranged on a two-dimensional turntable, and the pulsed laser emitted by the laser irradiates the target to form a light spot;

[0012] A four-quadrant photoelectric detection unit is used to receive the laser echo pulse diffusely reflected by the light spot on the target;

[0013] a near-infrared camera, used for imaging the light spot formed on the target;

[0014] a data processing unit connected to the four-quadrant photoelectric detection unit and the near-infrared camera;

[0015] A control unit is connected to the data processing unit, and the control unit includes a first control device for controlling the two-dimensional turntable and a second control device for controlling the near-infrared camera.

[0016] According to a laser far-field beam quality testing device provided by the present application, the first control device includes:

[0017] A servo controller connected to control the two-dimensional turntable to rotate horizontally or vertically;

[0018] An automatic alignment controller is connected to the data processing unit and the servo controller, and is used to control the servo controller through a PID algorithm according to the light spot position processed by the data processing unit.

[0019] According to a laser far-field beam quality testing device provided by the present application, the target is a planar target screen with a fixed reflectivity.

[0020] According to a laser far-field beam quality testing device provided by the present application, the four-quadrant photoelectric detection unit is connected to the data processing unit through an ADC acquisition unit. The ADC acquisition unit includes four photoelectric signal acquisition channels and one sum channel. The four photoelectric signal acquisition channels are used to collect the amplitudes of the four-quadrant laser pulse signals, and the sum channel is used to calculate the superposition value of the amplitudes of the four-quadrant laser pulse signals.

[0021] According to a laser far-field beam quality testing device provided by the present application, the second control device is a timing control unit, which is used to adjust the exposure time of the near-infrared camera and the detection time of the four-quadrant photoelectric detection unit.

[0022] According to the laser far-field beam quality testing device provided by the present application, a narrowband filter and an attenuation plate are provided at the front end of the near-infrared camera lens. The second control device is used to control the movement of the narrowband filter and attenuation plate to adjust the light transmission amount of the near-infrared camera.

[0023] According to a laser far-field beam quality testing device provided by the present application, the laser far-field beam quality testing device further includes a display unit, and the display unit is connected to the data processing unit.

[0024] The present application also provides a laser far-field beam quality testing method, applicable to any of the above-mentioned laser far-field beam quality testing devices, comprising:

[0025] S1. The laser emits a laser pulse to illuminate the target, forming a light spot on the target;

[0026] S2. Using a four-quadrant photoelectric detection unit to capture the laser echo pulse emitted by the light spot on the target, and calculate the angle information of the light spot on the target;

[0027] S3. Based on the spot angle information calculated in step S2, the first control device controls the two-dimensional turntable to adjust so that the laser irradiates the center of the target;

[0028] S4. Using the four-quadrant photoelectric detection unit again to capture the laser echo pulses emitted from the target, and calculating the spot angle information and laser pulse timing information on the target;

[0029] S5. Calculate the light spot angle information and laser pulse timing information on the target according to step S4, and adjust the near-infrared camera and the four-quadrant photoelectric detection unit through the second control device so that the imaging spot of the light spot on the target in the near-infrared camera is in the linear region of the four-quadrant photoelectric detection unit;

[0030] S6. Use a near-infrared camera to shoot the light spot on the target to obtain far-field non-saturated light spot imaging;

[0031] S7. Perform image analysis on the far-field non-saturated spot imaging obtained in step S6, and then perform evaluation calculation on the far-field beam quality of the laser pulse.

[0032] According to a laser far-field beam quality testing method provided in the present application, in step S5, adjusting the near-infrared camera includes reducing the exposure time of the near-infrared camera or increasing the attenuation of the attenuation plate at the front end of the near-infrared camera lens.

[0033] According to a laser far-field beam quality testing method provided by the present application, in step S7, performing an evaluation calculation of the laser pulse far-field beam quality includes calculating the coordinates of the center of gravity of the spot, the spot diameter, and the beam divergence angle of the spot;

[0034] The coordinates of the center of gravity of the light spot are calculated by the following formula:

[0035] Among them, x and y represent the horizontal and vertical directions of the spot image, and z represents the pixel value of the spot image. and represents the coordinates of the center of gravity of the light spot, and E(x, y, z) represents the distribution function of the light spot;

[0036] The spot diameter is calculated by the following formula:

[0037] in, represents the second-order moment of the center of gravity of the light spot in the x direction, Indicates the second-order moment of the center of gravity of the light spot in the y direction, d σ (z) represents the spot diameter;

[0038] The beam divergence angle of the light spot is calculated by the following formula:

[0039] Among them, Θ σ represents the beam divergence angle of the light spot, and L represents the distance from the laser to the light spot on the target.

[0040] The present application provides a laser far-field beam quality testing device and testing method. First, the spot position information obtained by the four-quadrant photoelectric detection unit is used to guide the rotation of the two-dimensional turntable so that the laser faces the target and forms a complete and undeformed spot. Then, based on the spot position information and laser pulse timing information obtained by the four-quadrant photoelectric detection unit, the near-infrared camera is guided to be adjusted, and accurate far-field non-saturated spot imaging that is not affected by the background is obtained by reducing the exposure time or increasing the attenuation of the attenuation plate. Finally, the far-field non-saturated spot imaging is calculated to obtain the evaluation result of the laser far-field beam quality. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] 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.

[0042] FIG1 is a schematic structural diagram of a laser far-field beam quality testing device provided by the present application;

[0043] FIG2 is a schematic diagram of the coordinated use of a four-quadrant photoelectric detection unit and a near-infrared camera during the testing process of the laser far-field beam quality testing device provided in this application.

[0044] Figure numerals: 1. Target; 2. Laser; 3. Two-dimensional turntable; 4. Four-quadrant photoelectric detection unit; 5. Near-infrared camera; 6. Data processing unit; 7. First control device; 71. Servo controller; 72. Automatic alignment controller; 8. Second control device; 9. ADC acquisition unit; 10. Display unit. DETAILED DESCRIPTION

[0045] 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.

[0046] 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.

[0047] 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.

[0048] 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.

[0049] 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.

[0050] The laser far-field beam quality testing device and testing method of the present application are described below with reference to FIG1 and FIG2 .

[0051] An embodiment of the present application provides a laser far-field beam quality testing device, as shown in Figure 1, comprising a target 1, a laser 2, a four-quadrant photoelectric detection unit 4, a near-infrared camera 5, a data processing unit 6 and a control unit, wherein the laser 2 is arranged on a two-dimensional turntable 3, and the pulsed laser emitted by the laser 2 irradiates the target 1 to form a light spot; the four-quadrant photoelectric detection unit 4 is used to receive the laser echo pulse emitted by the light spot on the target 1; the near-infrared camera 5 is used to image the light spot formed on the target 1; the data processing unit 6 is connected to the four-quadrant photoelectric detection unit 4 and the near-infrared camera 5; the control unit is connected to the data processing unit 6, and the control unit includes a first control device 7 for controlling the two-dimensional turntable 3 and a second control device 8 for controlling the near-infrared camera 5.

[0052] It is understood that the laser far-field beam quality testing device of this embodiment can be used for far-field spot position testing and beam quality assessment of laser rangefinders, laser radars, laser illuminators, and the like. Near-infrared camera 5 uses a camera capable of imaging near-infrared lasers and is used for detecting commonly used bands such as 1064nm and 1557nm. If the laser being tested is in other bands, such as the mid-infrared band, a mid-infrared camera needs to be replaced accordingly, but the principle remains the same.

[0053] Specifically, referring to Figure 1, the laser 2 irradiates the laser pulse vertically on the target 1 (in order to clearly illustrate all the lines in Figure 1, the laser pulse shown in the figure is not irradiated vertically, and the irradiation direction here needs to be understood as vertical irradiation). The laser pulse forms a short-term light spot on the target 1 and diffusely reflects to the surroundings.

[0054] First, the four-quadrant photoelectric detection unit 4 detects, amplifies, and collects the laser echo pulses, calculating the angle of the light spot position. Based on this angle, the first control device 7 controls the two-dimensional turntable 3 to perform two-dimensional position adjustment, adjusting the laser 2's light spot position on the target 1 so that the light spot path is perpendicular to the center of the target 1, forming a complete light spot on the target 1.

[0055] Next, the four-quadrant photoelectric detection unit 4 detects, amplifies, and collects the adjusted laser echo pulses, confirming and calculating the angular information of the light spot position and obtaining the laser pulse timing information. Based on the angular information of the light spot position, the near-infrared camera 5 can easily find the light spot position. The near-infrared camera 5 does not need to operate in the saturation region. By reducing the exposure time or increasing the attenuation of the attenuation plate, the imaging spot of the far-field light spot in the near-infrared camera 5 can be placed in the linear region of the four-quadrant photoelectric detection unit 4, and the near-infrared camera 5 can be used to obtain far-field non-saturated light spot imaging.

[0056] Finally, image processing is performed based on the far-field non-saturated spot imaging obtained by the near-infrared camera 5 to obtain accurate data of the spot. After calculation, the far-field spot diameter is obtained, and then the beam divergence angle is calculated to evaluate the far-field beam quality of the laser pulse.

[0057] It should be understood that the laser far-field beam quality testing device of this embodiment first guides the two-dimensional turntable 3 to rotate based on the spot position information obtained by the four-quadrant photoelectric detection unit 4, so that the laser 2 can form a complete spot on the target 1; then, based on the spot position information and laser pulse timing information obtained by the four-quadrant photoelectric detection unit 4, it guides the near-infrared camera 5 to adjust, and obtains accurate far-field non-saturated spot imaging that is not affected by the background by reducing the exposure time or increasing the attenuation of the attenuation plate; finally, the far-field non-saturated spot imaging is calculated to obtain the evaluation result of the laser far-field beam quality.

[0058] In some embodiments of a laser far-field beam quality testing device of the present application, the first control device 7 includes a servo controller 71 and an automatic alignment controller 72, wherein the servo controller 71 is connected to control the two-dimensional turntable 3 to rotate horizontally or vertically; the automatic alignment controller 72 is connected to the data processing unit 6 and the servo controller 71, and is used to control the servo controller 71 through a PID algorithm according to the spot position processed by the data processing unit 6.

[0059] The first control device 7 is used to control the rotation of the two-dimensional turntable 3 so that the laser 2 reaches a suitable emission angle. The two-dimensional turntable 3 is a rotating device that can realize deflection in the horizontal and vertical directions. The laser 2 is mounted on the two-dimensional turntable 3. The position of the light spot irradiated by the laser 2 on the target 1 can be adjusted by the deflection of the two-dimensional turntable 3. Specifically, based on the light spot position information detected by the four-quadrant photoelectric detection unit 4 and the angle information of the light spot position, the automatic alignment controller 72 continuously uses the angular deviation of the light spot position as input, and controls the servo controller 71 through the PID algorithm to drive the two-dimensional turntable 3 to deflect, adjust the direction of the laser 2, and align the laser 2 with the target target screen 1. The target target 1 is a target screen with a fixed reflectivity, and the surface of the target screen is a standard plane, thereby increasing the light spot imaging quality and facilitating the evaluation of the far-field beam quality of the laser pulse in the later stage.

[0060] In other embodiments, the four-quadrant photoelectric detection unit 4 is connected to the data processing unit 6 via the ADC acquisition unit 9. The four-quadrant photoelectric detection unit 4 can be a four-quadrant APD detection unit, including a four-quadrant APD laser detector, a preamplifier circuit, a high-voltage circuit, and a signal amplification circuit. The APD detector uses its high sensitivity to detect and amplify the laser echo pulse, and then performs data acquisition and digital-to-analog conversion through the ADC acquisition unit 9. The ADC acquisition unit 9 includes four photoelectric signal acquisition channels and one sum channel. The four photoelectric signal acquisition channels are used to collect the amplitude of the four-quadrant laser pulse signal, and the sum channel is used to calculate the superposition value of the amplitude of the four-quadrant laser pulse signal. After the four-channel photoelectric signal is collected by the ADC acquisition unit 9, the angle information of the spot position is calculated, and the laser timing of the sum channel (the channel where the four-channel signal is superimposed) is calculated at the same time to trigger the near-infrared camera. Specifically, the ADC acquisition unit 9 performs amplitude sampling on the amplified four-channel laser pulse signal, and calculates the angle information of the strong laser pulse through sum and difference operations. At the same time, it automatically sets the appropriate trigger threshold for the and channels and measures the laser pulse arrival time for the triggering of the near-infrared camera and the laser pulse frequency stability test.

[0061] The amplitude sampling data collected by the ADC acquisition unit 9 is processed by the data processing unit 6. Simultaneously, the data processing unit 6 calculates the light spot angle and performs image processing based on the laser echo pulse waveform information from the ADC acquisition unit 9 and the image captured by the near-infrared camera 5. The position of the light spot on the target screen 1 is obtained by using the laser echo pulse waveform information detected by the four-quadrant photoelectric detection unit 4 and collected by the ADC acquisition unit 9. This information facilitates the location of the light spot within the image when processing the image captured by the near-infrared camera 5.

[0062] To improve the signal-to-noise ratio of laser pulse detection and eliminate the need for the near-infrared camera to operate in the saturation region, this embodiment can be implemented in two ways. One way is to place a narrowband filter and attenuation plate at the front end of the lens of the near-infrared camera 5 when the light pulse of the laser 2 under test belongs to a single wavelength band to reduce interference from light waves in other wavelength bands. The other way is to trigger the exposure of the near-infrared camera 5 based on the laser pulse timing and laser pulse period detected by the four-quadrant photoelectric detection unit 4, thereby reducing the exposure time. Both methods can ensure that the far-field light spot of the near-infrared camera 5 is in the linear region of the four-quadrant photoelectric detection unit 4, resulting in far-field non-saturated light spot imaging, which facilitates the subsequent evaluation of the beam quality.

[0063] Specifically, to achieve one of the above-mentioned methods, in some embodiments, the second control device 8 is a timing control unit, which is used to adjust the exposure time of the near-infrared camera 5 and the detection time of the four-quadrant photodetection unit 4. The timing control unit combines the timing information of the laser pulse obtained by the four-quadrant photodetection unit 4 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 near-infrared camera 5 and the detection time of the APD laser detector, so as to better capture the pulse spot.

[0064] To achieve another method of one of the above, in some embodiments, a narrow-band filter and an attenuation plate are provided at the front end of the lens of the near-infrared camera 5, and the second control device 8 is used to control the movement of the narrow-band filter and the attenuation plate to adjust the amount of light passing through the near-infrared camera 5. The narrow-band filter can reduce background interference, and by increasing the attenuation of the attenuation plate, the imaging spot of the far-field light spot in the near-infrared camera 5 is in the linear region of the APD laser detector, thereby obtaining far-field non-saturated light spot imaging.

[0065] In some embodiments, a laser far-field beam quality testing device of the present application also includes a display unit 10, which is connected to the data processing unit 6. The main body of the display unit 10 is a display for displaying the processing results of the data processing unit 6. The far-field non-saturated spot imaging taken by the near-infrared camera 5 obtains corresponding calculation templates and data through image processing, which are used for the subsequent calculation and evaluation of the beam quality, thereby evaluating the far-field spot and spot position of the laser.

[0066] The laser far-field beam quality testing method provided in this application is described below. The laser far-field beam quality testing method described below and the laser far-field beam quality testing device described above can be referenced to each other.

[0067] In one embodiment of the present application, a method for testing the far-field beam quality of a laser is provided, comprising the following steps.

[0068] S1. Laser 2 emits a laser pulse which irradiates the target 1, forming a light spot on the target 1.

[0069] S2. Utilize the four-quadrant photoelectric detection unit 4 to capture the laser echo pulses emitted by the light spot on the target 1 and calculate the angle information of the light spot on the target 1.

[0070] S3 . Based on the spot angle information calculated in step S2 , the first control device 7 controls the two-dimensional turntable 3 to adjust so that the laser 2 irradiates the center of the target 1 .

[0071] S4. The four-quadrant photoelectric detection unit 4 is used again to capture the laser echo pulses emitted from the target 1, and the light spot angle information and laser pulse timing information on the target 1 are calculated.

[0072] S5. Calculate the light spot angle information and laser pulse timing information on the target 1 according to step S4, and adjust the near-infrared camera 5 and the four-quadrant photoelectric detection unit 4 through the second control device 8 so that the imaging spot of the light spot on the target 1 in the near-infrared camera 5 is in the linear region of the four-quadrant photoelectric detection unit 4.

[0073] S6. Use the near-infrared camera 5 to shoot the light spot on the target 1 to obtain far-field non-saturated light spot imaging.

[0074] S7. Perform image analysis on the far-field non-saturated spot imaging obtained in step S6, and then perform evaluation calculation on the far-field beam quality of the laser pulse.

[0075] This example uses a 1064nm DPL laser, commonly used in laser rangefinders. The laser has a wavelength of 1064nm, a pulse width of approximately 10ns, and a pulse period of 20Hz. As shown in Figure 1, laser 2 irradiates target 1 with a laser pulse, creating a short-lived spot on target 1 that is diffusely reflected toward the surrounding area. The duty cycle of laser 2 is set to t, which serves as the basis for calculating the triggering of near-infrared camera 5. A 1064nm narrowband filter is placed in front of the lens of near-infrared camera 5 to reduce background interference. The camera is set to external trigger mode. When the external trigger signal arrives, the near-infrared camera 5 initiates exposure.

[0076] During the automatic alignment of the laser spot (corresponding to the above steps S2 and S3), with the help of the spot position information obtained by the four-quadrant photoelectric detection unit 4, the automatic alignment controller 72 takes the angular deviation of the four-quadrant photoelectric detection unit 4 as input, and uses the PID algorithm to control the servo controller 71 to drive the two-dimensional turntable 3 to adjust the direction of the laser 2 according to the spot position information, so that the laser 2 is aligned with the target 1, so that the spot image of the near-infrared camera 5 is located at the center of the target 1 without distortion.

[0077] After the laser spot is automatically aligned, the far-field non-saturated spot of the far-field spot can be accurately obtained by using the four-quadrant photoelectric detection unit 4 and the near-infrared camera 5 in conjunction. Specifically, as shown in Figure 2, the laser pulse is first captured by the four-quadrant photoelectric detection unit 4 and forms an undistorted waveform. The ADC acquisition unit 9 samples the amplitude of the four-way laser pulse signal, calculates the spot angle information, and calculates the pulse arrival time t1 using the adaptive threshold in the sum channel. t1+t is the arrival time of the next pulse. The timing control unit turns on the near-infrared camera 5 in advance by Δt / 2 time (Δt is the exposure time), so that the complete laser pulse can be captured by the near-infrared camera 5 without unnecessary background light interference. Starting from the second pulse, the picture captured by the near-infrared camera 5 and the pulse data collected by the ADC acquisition unit 9 are matched one by one and sent to the data processing unit 6 for processing.

[0078] When imaging the light spot, the near-infrared camera 5 selects an appropriate attenuation according to the intensity of the measured laser and the saturation threshold of the detector to fully utilize the dynamic range of the detector and make the imaging spot of the far-field light spot in the near-infrared camera 5 fall within the linear region of the detector, thereby enabling the far-field beam quality of the laser pulse to be evaluated.

[0079] The evaluation calculation of the far-field beam quality of the laser pulse may include calculating the coordinates of the center of gravity of the spot, the spot diameter, and the beam divergence angle of the spot.

[0080] The coordinates of the center of gravity of the light spot are calculated using the following formulas 1 and 2:

[0081] Among them, x and y represent the horizontal and vertical directions of the spot image, and z represents the pixel value of the spot image. and represents the coordinates of the center of gravity of the light spot, and E(x, y, z) represents the distribution function of the light spot;

[0082] The spot diameter is calculated using the following formulas:

[0083] in, represents the second-order moment of the center of gravity of the light spot in the x direction, Indicates the second-order moment of the center of gravity of the light spot in the y direction, d σ (z) represents the spot diameter;

[0084] The beam divergence angle of the light spot is calculated using the following formula 6:

[0085] Among them, Θ σrepresents the beam divergence angle of the light spot, and L represents the distance from the laser to the light spot on the target.

[0086] The coordinates of the center of gravity of the light spot, the diameter of the light spot, and the beam divergence angle of the light spot obtained by the above calculation can be used to evaluate the far-field beam quality of the laser pulse. The final calculation results can be displayed on the display unit 10 to output the final laser far-field beam quality test results.

[0087] 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. 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 application.

Claims

1. A laser far-field beam quality testing device, comprising: Target (1); A laser (2) is arranged on a two-dimensional turntable (3), and the pulsed laser emitted by the laser (2) irradiates the target (1) to form a light spot; A four-quadrant photoelectric detection unit (4) is used to receive laser echo pulses diffusely reflected by the light spot on the target (1); A near-infrared camera (5) for imaging the light spot formed on the target (1); a data processing unit (6), connected to the four-quadrant photoelectric detection unit (4) and the near-infrared camera (5); A control unit is connected to the data processing unit (6), and the control unit includes a first control device (7) for controlling the two-dimensional turntable (3) and a second control device (8) for controlling the near-infrared camera (5).

2. The laser far-field beam quality testing device according to claim 1, wherein: The first control device (7) comprises: A servo controller (71) is connected to control the two-dimensional turntable (3) to rotate horizontally or vertically; An automatic alignment controller (72) is connected to the data processing unit (6) and the servo controller (71) and is used to control the servo controller (71) through a PID algorithm according to the light spot position processed by the data processing unit (6).

3. The laser far-field beam quality testing device according to claim 1, wherein: The target (1) is a flat target screen with a fixed reflectivity.

4. The laser far-field beam quality testing device according to claim 1, wherein: The four-quadrant photoelectric detection unit (4) is connected to the data processing unit (6) via an ADC acquisition unit (9), wherein the ADC acquisition unit (9) comprises four photoelectric signal acquisition channels and one sum channel, wherein the four photoelectric signal acquisition channels are used to acquire the amplitudes of the four-quadrant laser pulse signals, and the sum channel is used to calculate the superposition value of the amplitudes of the four-quadrant laser pulse signals.

5. The laser far-field beam quality testing device according to claim 1, wherein: The second control device (8) is a timing control unit, which is used to adjust the exposure time of the near-infrared camera (5) and the detection time of the four-quadrant photoelectric detection unit (4).

6. The laser far-field beam quality testing device according to claim 1, wherein: A narrowband filter and an attenuation plate are provided at the front end of the lens of the near-infrared camera (5); and the second control device (8) is used to control the movement of the narrowband filter and the attenuation plate to adjust the light transmission amount of the near-infrared camera (5).

7. The laser far-field beam quality testing device according to any one of claims 1 to 6, wherein: The laser far-field beam quality testing device further comprises a display unit (10), and the display unit (10) is connected to the data processing unit (6).

8. A laser far-field beam quality testing method, applicable to the laser far-field beam quality testing device according to any one of claims 1 to 7, comprising: S1, the laser (2) emits a laser pulse to illuminate the target (1), forming a light spot on the target (1); S2, using a four-quadrant photoelectric detection unit (4) to capture the laser echo pulse emitted by the light spot on the target (1), and calculate the angle information of the light spot on the target (1); S3, according to the spot angle information calculated in step S2, the first control device (7) controls the two-dimensional turntable (3) to adjust so that the laser (2) irradiates the center position of the target (1); S4, again using the four-quadrant photoelectric detection unit (4) to capture the laser echo pulses emitted from the target (1), and calculating the spot angle information and laser pulse timing information on the target (1); S5, calculating the light spot angle information and laser pulse timing information on the target (1) according to step S4, and adjusting the near-infrared camera (5) and the four-quadrant photoelectric detection unit (4) through the second control device (8) so that the light spot on the target (1) is located in the linear region of the four-quadrant photoelectric detection unit (4) when the imaging light spot of the near-infrared camera (5) is formed; S6, using a near-infrared camera (5) to photograph the light spot on the target (1) to obtain far-field non-saturated light spot imaging; S7. Perform image analysis on the far-field non-saturated spot imaging obtained in step S6, and then perform evaluation calculation on the far-field beam quality of the laser pulse.

9. The laser far-field beam quality testing method according to claim 8, wherein: In step S5, the adjusting of the near-infrared camera (5) includes reducing the exposure time of the near-infrared camera (5) or increasing the attenuation of the attenuation plate at the front end of the lens of the near-infrared camera (5).

10. The laser far-field beam quality testing method according to claim 8, wherein: In step S7, the evaluation calculation of the far-field beam quality of the laser pulse is performed, including calculating the coordinates of the center of gravity of the spot, the diameter of the spot, and the beam divergence angle of the spot; The coordinates of the center of gravity of the light spot are calculated by the following formula: Among them, x and y represent the horizontal and vertical directions of the spot image, and z represents the pixel value of the spot image. and represents the coordinates of the center of gravity of the light spot, and E(x, y, z) represents the distribution function of the light spot; The spot diameter is calculated by the following formula: in, represents the second-order moment of the center of gravity of the light spot in the x direction, represents the second-order moment of the center of gravity of the light spot in the y direction, d σ (z) represents the spot diameter; The beam divergence angle of the light spot is calculated by the following formula: Among them, Θ σ represents the beam divergence angle of the light spot, and L represents the distance from the laser to the light spot on the target.

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