A laser divergence angle detection system, method, and apparatus based on differential measurement

Abstract

This invention proposes a laser divergence angle detection system, method, and device based on differential measurement, relating to the field of optical communication technology. It includes: a displacement feedback control module, a spot acquisition module, and a geometric analysis processing module. The displacement feedback control module is configured to move the target surface of the optical screen from a first position to a second position along the laser optical axis and transmit the position information to the geometric analysis processing module. The spot acquisition module is configured to generate a diverging beam to be measured, perform preliminary collimation and shaping on the incident diverging beam, receive the diverging beam, convert the diverging beam into a spatially distributed spot signal, and convert the spot signal into a spot image. The geometric analysis processing module is configured to acquire the position information and the size information corresponding to the spot images before and after position adjustment, and determine the divergence angle of the diverging beam based on the position information and the size information.

Description

Technical Field

[0001] This invention relates to the field of optical communication technology, and in particular to a laser divergence angle detection system, method and device based on differential measurement. Background Technology

[0002] In the current era of rapid development in laser technology, the laser divergence angle, as one of the core parameters for measuring laser beam quality, plays an irreplaceable and crucial role in many cutting-edge fields such as laser processing, laser communication, and lidar. In laser processing, the laser divergence angle directly affects the precision and quality of the processing. Precise control of the laser divergence angle ensures that laser energy is evenly distributed on the material surface, enabling high-precision cutting, welding, drilling, and other operations. For example, in microelectronic chip manufacturing, even minute changes in the laser divergence angle can lead to connection deviations or damage to chip circuits, severely impacting chip performance and yield. Therefore, accurate measurement of the laser divergence angle is essential for the precise control of laser processing quality.

[0003] Laser communication, as a crucial component of modern communication technology, relies on the precise transmission of laser beams in space to achieve high-speed, high-capacity information transfer. The stability of the laser divergence angle directly affects the reliability of the optical communication link. During long-distance laser communication, the laser beam must propagate through the atmosphere, where air turbulence and thermal gradient effects inevitably interfere with it. Air turbulence causes random changes in the atmospheric refractive index, leading to bending and flickering of the laser beam's propagation path, resulting in distortion of the light spot at the receiving end. Thermal gradient effects cause uneven density in the local atmosphere, further exacerbating the distortion. These distortions alter the energy distribution and propagation direction of the laser beam, increasing signal attenuation and bit error rate, severely impacting the stability of the communication link. Accurate measurement of the laser divergence angle helps us understand the mechanisms by which these interference factors affect the laser beam, enabling us to implement effective compensation measures and ensure high-quality laser communication transmission. Summary of the Invention

[0004] In view of this, the present invention proposes a laser divergence angle detection system, method and device based on differential measurement.

[0005] The technical solution of this invention is implemented as follows: The first aspect of this invention provides a laser divergence angle detection system based on differential measurement, comprising: a displacement feedback control module, a spot acquisition module, and a geometric analysis processing module; wherein, The displacement feedback control module is configured to move the optical screen target surface from a first position to a second position along the laser optical axis, and transmit the position information to the geometric analysis processing module; the position information includes the first position and the second position; The light spot acquisition module includes a laser source, a beam shaping module, an acquisition submodule, and an area array detector. The laser source generates a divergent beam to be tested. The beam shaping module is configured to perform preliminary collimation and shaping on the incident divergent beam. The acquisition submodule includes the light screen target surface and is configured to receive the divergent beam to be tested and convert it into a spatially distributed light spot signal. The area array detector is configured to convert the light spot signal into a light spot image. The geometric analysis processing module is configured to acquire the position information and the size information corresponding to the light spot image before and after the position adjustment, and to determine the divergence angle of the diverging beam to be tested based on the position information and the size information.

[0006] Based on the above technical solutions, preferably, the displacement feedback control module includes a motion slide and a position encoder; When the motion slide receives a preset control command, it drives the platform with the fixed light screen target to move from a first position to a second position in the direction of the laser optical axis; the position encoder is configured to convert the position information corresponding to the first position and the second position into position information, and transmit the position information to the geometric analysis processing module.

[0007] Based on the above technical solutions, preferably, the displacement feedback control module further includes a PID controller, a temperature sensor, and a vibration damping device; the PID controller is configured to compensate for the backlash error generated during the movement of the light screen target surface in real time, the temperature sensor is configured to monitor changes in ambient temperature and correct the position information based on the monitoring data, and the vibration damping device is configured to eliminate residual mechanical vibration.

[0008] Based on the above technical solutions, preferably, the light spot acquisition module is fixed to the first adapter plate by screws, and the first adapter plate is connected to the first vertical electric module. The beam shaping module is connected and installed on the left-right moving electric module through the optomechanical connecting rod assembly, and the area array detector is fixed to the second vertical electric module by screws connected to the second adapter plate.

[0009] Based on the above technical solutions, preferably, the light spot acquisition module is configured to acquire the light spot after a preset time delay after the target surface of the light screen has stabilized.

[0010] More preferably, a second aspect of the present invention provides a laser divergence angle detection method based on differential measurement, applied to the laser divergence angle detection system based on differential measurement described in the first aspect, comprising: The motion slide is controlled to move the light screen target surface from the first position to the second position; Acquire the spot information generated by the divergent beam under test when it is at a first position and a second position on the target surface of the optical screen after propagation; the spot information includes a first size information corresponding to the first position and a second size information corresponding to the second position. The divergence angle of the diverging beam to be measured is determined based on the actual displacements at the first and second positions, as well as the first and second size information.

[0011] Based on the above technical solutions, preferably, the step of acquiring the light spot information generated when the divergent beam to be tested is at the first position and the second position on the target surface of the optical screen after propagation includes: A Gaussian-elliptic hybrid fitting algorithm is used to perform equivalent fitting on the non-ideal light spots at the first and second positions to determine the first size information of the non-ideal light spots at the first position and the second size information of the non-ideal light spots at the second position.

[0012] Based on the above technical solutions, preferably, the step of using a Gaussian-elliptic hybrid fitting algorithm to perform equivalent fitting of the non-ideal light spots at the first and second positions includes: If the ellipticity of the non-ideal light spot is greater than the first threshold, the least squares ellipse fitting algorithm is used to perform an equivalent fitting on the non-ideal light spot. If the ellipticity of the non-ideal light spot is not greater than the first threshold, a Gaussian model is used to perform an equivalent fitting on the non-ideal light spot.

[0013] Based on the above technical solution, preferably, before determining the divergence angle of the diverging beam to be measured based on the actual displacements of the first and second positions and the first and second size information, the method further includes: The displacements at the first and second positions are compensated and corrected using a real-time centroid offset detection mechanism and a temperature compensation model to obtain the actual displacements.

[0014] More preferably, a third aspect of the present invention provides a laser divergence angle detection device based on differential measurement, including the laser divergence angle detection system based on differential measurement described in the first aspect.

[0015] The laser divergence angle detection system, method, and device based on differential measurement of the present invention have the following advantages over the prior art: 1. The displacement feedback control module precisely moves the target surface of the light screen and feeds back the position information. The spot acquisition module completes the shaping of the diverging beam to be measured, the spot signal conversion and image acquisition. The geometric analysis processing module determines the divergence angle by combining the position and spot size information. This achieves high-precision measurement of the laser divergence angle and realizes the miniaturization of the measuring device, reducing the overall size of the system. It effectively solves the problems of air turbulence, thermal gradient effect causing spot distortion during long-distance transmission and vibration-induced micro-displacement of the detector causing milliradian-level angle errors in existing technologies.

[0016] 2. The PID controller can compensate for the hysteresis error generated during the movement of the target screen in real time, keeping the hysteresis error within a very small range and ensuring the accuracy of the target screen movement. A temperature sensor monitors ambient temperature changes in real time and corrects the position information based on the monitoring data, eliminating the interference of temperature factors on the measurement results. A vibration damping device absorbs and isolates vibration energy, minimizing the impact of residual mechanical vibration on the target screen, ensuring the stability of the target screen during the measurement process, and significantly improving the accuracy and reliability of laser divergence angle measurement.

[0017] 3. By controlling the sliding stage to change the position of the target screen and acquiring spot information from two different positions, the divergence angle can be calculated. This method is adaptable to various measurement scenarios, whether it's short-distance laboratory measurements or long-distance real-world applications. The position of the target screen can be flexibly adjusted for measurement, and it is applicable to various common laser light sources, exhibiting strong versatility and flexibility. Furthermore, this solution only requires controlling the sliding stage to move the target screen and acquiring spot information from two positions to complete the measurement. The system structure is relatively simple, which not only reduces hardware costs but also simplifies system complexity and maintenance, while improving system reliability and stability. Attached Figure Description

[0018] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0019] Figure 1 A schematic diagram of a laser divergence angle detection system based on differential measurement is provided in an embodiment of the present invention; Figure 2 A schematic flowchart of a laser divergence angle detection method based on differential measurement provided in an embodiment of the present invention; Figure 3 This is a schematic diagram of the structure of a laser divergence angle detection device based on differential measurement provided in an embodiment of the present invention. Detailed Implementation

[0020] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0021] In some embodiments, such as Figure 1 As shown, Figure 1 This is a schematic diagram of a laser divergence angle detection system based on differential measurement, provided by an embodiment of the present invention. The laser divergence angle detection system 100 based on differential measurement provided by the present invention includes: a displacement feedback control module 110, a spot acquisition module 120, and a geometric analysis processing module 130; wherein, The displacement feedback control module 110 is configured to move the target surface of the light screen from a first position to a second position in the direction of the laser optical axis, and transmit the position information to the geometric analysis processing module; the position information includes the first position and the second position.

[0022] The light spot acquisition module 120 includes a laser source, a beam shaping module, an acquisition submodule, and an area array detector. The laser source generates a divergent beam to be tested. The beam shaping module is configured to perform preliminary collimation and shaping on the incident divergent beam to be tested. The acquisition submodule includes a light screen target surface and is configured to receive the divergent beam to be tested and convert it into a spatially distributed light spot signal. The area array detector is configured to convert the light spot signal into a light spot image.

[0023] The geometric analysis processing module 130 is configured to acquire position information and size information corresponding to the light spot images before and after position adjustment, and to determine the divergence angle of the diverging beam to be measured based on the position information and size information.

[0024] In this embodiment, the displacement feedback control module 110 can employ a high-precision linear guide slide, servo motor, and grating displacement sensor. For the spot acquisition module 120, the laser source is the component that generates the divergent beam to be measured; the beam shaping module can consist of multiple lenses; the acquisition submodule includes a light screen target surface, which is mounted via a magnetic quick-release clamp, allowing for replacement of diffuse or transmissive target surfaces within 3 seconds, and is compatible with laser power from 10 watts to 10 kilowatts. The area array detector uses a charge-coupled device (CCD) or complementary metal-oxide-semiconductor (CMOS) image sensor. Taking a scientific-grade CMOS sensor as an example, its quantum efficiency at 1550nm wavelength is greater than 80%, and its exposure synchronization error is less than 1 millisecond; it can switch filter groups, supporting measurements in wavelengths including but not limited to 405nm, 808nm, 1064nm, and 1550nm. The geometric analysis processing module 130 mainly includes a data acquisition interface, a processor, and a memory. The data acquisition interface receives position information transmitted from the displacement feedback control module and spot image data transmitted from the area array detector. The processor processes and analyzes the acquired data, and the memory stores measurement data and processing programs. Position information reflects the actual position of the target surface on the laser optical axis, while the spot image data includes information such as the shape, size, and intensity distribution of the spot. Specifically, the processor processes the acquired spot image, using image processing algorithms such as edge detection and binarization to extract the spot boundary and calculate the spot's size information, such as its diameter or area. After acquiring the spot size information of the target surface at the first and second positions, the divergence angle of the laser beam is calculated based on the principles of geometric optics, which state that the divergence angle is related to the spot size and propagation distance. Given the actual displacement of the target surface at the first and second positions and the corresponding spot size information, a mathematical model is established, utilizing trigonometric relationships or the principle of similar triangles, to calculate the divergence angle of the beam to be measured.

[0025] In some embodiments, the displacement feedback control module 110 includes a motion slide and a position encoder; When the motion slide receives a preset control command, it drives the platform with the fixed light screen target to move from a first position to a second position in the direction of the laser optical axis; the position encoder is configured to convert the position information corresponding to the first position and the second position into position information and transmit the position information to the geometric analysis processing module.

[0026] In this embodiment, the displacement feedback control module 110 mainly includes a motion slide, a drive motor, and a position encoder. The motion slide is used to support the optical screen target surface and realize its precise movement along the laser optical axis; the drive motor provides power to the motion slide, specifically a piezoelectric ceramic-screw composite slide. The core function of the displacement feedback control module is to accurately move the optical screen target surface from a first position to a second position along the laser optical axis, and the position encoder transmits the accurate position information to the geometric analysis processing module, while simultaneously compensating for backlash errors during the movement process in real time and eliminating the influence of ambient temperature changes and mechanical residual vibrations on position measurement.

[0027] In some embodiments, the displacement feedback control module 110 further includes a PID controller, a temperature sensor, and a vibration damping device; the PID controller is configured to compensate for the backlash error generated during the movement of the light screen target surface in real time, the temperature sensor is configured to monitor changes in ambient temperature and correct the position information based on the monitoring data, and the vibration damping device is configured to eliminate residual mechanical vibration.

[0028] In this embodiment, the drive motor drives the moving slide table to move under the action of the control signal. The displacement sensor measures the position of the moving slide table in real time and feeds the position information back to the PID controller. The PID controller calculates based on the preset position value and the feedback position value, and outputs a control signal to adjust the speed and direction of the drive motor, so that the moving slide table moves accurately to the target position, realizing the precise movement of the optical screen target surface from the first position to the second position. The temperature sensor monitors the ambient temperature in real time and transmits the temperature data to the geometric analysis processing module. The geometric analysis processing module corrects the position information measured by the displacement sensor according to the preset temperature-displacement compensation model, eliminating the influence of temperature factors on position measurement. The vibration damping device can adopt a spring-damping system or air spring structure. When external vibration is transmitted to the moving slide table, the vibration damping device absorbs and isolates the vibration energy through the elastic deformation of the spring and the energy dissipation of the damping, reducing the impact of vibration on the moving slide table and keeping the optical screen target surface stable during the measurement process.

[0029] In some embodiments, the spot acquisition module 120 is fixed to the first adapter plate by screws, and the first adapter plate is connected to the first vertical motorized module. The beam shaping module is connected and installed on the left-right moving motorized module through the optomechanical connecting rod assembly, and the area array detector is fixed to the second vertical motorized module through the second adapter plate and screws.

[0030] The light spot acquisition module 120 is composed of multiple sub-components connected in a specific manner. The main body of the light spot acquisition module is fixed to the first adapter plate with screws. The first adapter plate is connected to the first vertical motorized module, enabling the light spot acquisition module to move in the vertical direction. The beam shaping module is mounted on the left-right moving motorized module via an optomechanical connecting rod assembly, allowing for horizontal adjustment. The area array detector is connected to the second vertical motorized module via a second adapter plate and screws, enabling it to move independently in the vertical direction.

[0031] In one optional embodiment, the first adapter plate can be a flat plate with a certain strength and rigidity, on which threaded holes matching the fixing screws of the light spot acquisition module are provided, as well as an interface for connecting to the first vertical electric module, such as a guide rail slider mating structure or a threaded connection structure. The first vertical electric module is typically composed of a motor, a lead screw, and a guide rail. The motor drives the lead screw to rotate, causing the nut mating with the lead screw and the first adapter plate fixed to the nut to move linearly along the guide rail. After the motor of the first vertical electric module is powered on, it rotates a certain angle according to the input control signal, driving the lead screw to rotate. Due to the threaded engagement between the nut and the lead screw and the limiting effect of the guide rail, the nut can only move linearly along the lead screw, thereby driving the first adapter plate and the light spot acquisition module to move in the vertical direction. By controlling the rotation direction and pulse number of the motor, the moving distance and direction of the light spot acquisition module can be precisely controlled. The beam shaping module consists of multiple lenses, which are mounted in specific lens mounts with interfaces for fixing. The optomechanical connector assembly includes a connector, connectors, etc. The connector is a slender rod-shaped structure, and the connector is used to connect the connector to the lens mount of the beam shaping module and the left-right moving electric module. The structure of the left-right moving electric module is similar to that of the first vertical electric module, consisting of a motor, lead screw, guide rail, etc., to achieve linear motion in the horizontal direction. The motor of the second vertical electric module drives the lead screw to rotate, causing the nut, the second adapter plate fixed on the nut, and the area array detector to move linearly along the guide rail. By controlling the movement of the motor, the position of the area array detector can be precisely adjusted to maintain a suitable distance and angle with the target surface of the light screen to obtain the best spot image acquisition effect.

[0032] In some embodiments, the spot acquisition module 120 is configured to acquire the spot after a preset time delay following the stabilization of the target surface of the light screen.

[0033] During the operation of the spot acquisition module 120, when the laser beam is projected onto the target surface of the screen, the spot may not reach a stable state instantaneously due to beam propagation characteristics, minor vibrations of optical components, or environmental interference. The function of configuring a preset delay for spot acquisition allows the spot sufficient time to stabilize, reducing acquisition errors caused by spot instability and thus obtaining more accurate spot information.

[0034] In some embodiments, please refer to Figure 2 , Figure 2 A schematic flowchart of a laser divergence angle detection method based on differential measurement is provided in an embodiment of the present invention; the laser divergence angle detection method based on differential measurement is applied to the above-mentioned laser divergence angle detection system based on differential measurement, including: S210, control the motion slide to move the light screen target surface from the first position to the second position.

[0035] S220, acquire the light spot information generated when the divergent beam to be tested is at the first position and the second position on the target surface of the screen after propagation; the light spot information includes the first size information corresponding to the first position and the second size information corresponding to the second position.

[0036] S230, the divergence angle of the diverging beam to be measured is determined based on the actual displacement of the first position and the second position, as well as the first size information and the second size information.

[0037] In this embodiment, each module, including the laser source, motion slide, and displacement encoder, is initialized to ensure normal operation. The motion slide moves the optical screen target to a first position, and the displacement encoder records this position information. The laser source is activated, and the spot acquisition module acquires the spot image of the optical screen target at the first position. The first size information of the spot is obtained through the geometric analysis processing module. The motion slide moves the optical screen target to a second position, and the displacement encoder records the actual displacement between the two positions. The spot acquisition module acquires the spot image of the optical screen target at the second position again, and the second size information of the spot is obtained through the geometric analysis processing module. Given the actual displacement of the optical screen target at the first and second positions and the corresponding spot size information, the divergence angle of the beam to be measured can be calculated by establishing a mathematical model and utilizing trigonometric function relationships or the principle of similar triangles.

[0038] In some embodiments, S220, acquiring the light spot information generated when the divergent beam to be tested is at the first position and the second position on the target surface of the screen after propagation includes: A Gaussian-elliptic hybrid fitting algorithm is used to perform equivalent fitting on the non-ideal light spots at the first and second positions, thereby determining the first size information corresponding to the non-ideal light spots at the first position and the second size information corresponding to the second position.

[0039] Laser beams can be affected by various factors during propagation, leading to different types of non-ideal characteristics in the beam spot, such as elliptical distortion, asymmetric distribution, and multi-peak structure. For example, factors like temperature, humidity, and vibration can affect the laser beam and the screen, causing changes in the beam spot shape. The Gaussian-elliptic hybrid fitting algorithm combines the characteristics of Gaussian functions and elliptic equations, enabling a more accurate description of the morphology of non-ideal beam spots. When the beam spot exhibits a certain degree of elliptical distortion, this algorithm can accurately fit the major and minor axes of the ellipse, thus determining the beam spot size more precisely. Compared to using only Gaussian fitting or simple geometric measurement methods, this significantly improves the accuracy of size measurement.

[0040] In some embodiments, a Gaussian-elliptic hybrid fitting algorithm is used to perform equivalent fitting on the non-ideal light spots at the first and second positions, including: When the ellipticity of a non-ideal light spot is greater than the first threshold, the least squares ellipse fitting algorithm is used to perform an equivalent fitting on the non-ideal light spot. If the ellipticity of the non-ideal light spot is not greater than the first threshold, a Gaussian model is used to perform an equivalent fitting on the non-ideal light spot.

[0041] When the ellipticity of a non-ideal light spot exceeds a first threshold, the spot shape deviates significantly from a circle and approaches an ellipse. In this case, a least-squares elliptic fitting algorithm can accurately determine the geometric parameters of the ellipse, such as the major axis, minor axis, center coordinates, and rotation angle, by minimizing the fitting error based on the ellipse equation. When the ellipticity is not greater than the first threshold, the spot shape is close to a circle, exhibiting good symmetry and conforming to the characteristics of a Gaussian distribution. The Gaussian model can well describe the energy distribution of such a circular light spot. By fitting the parameters of the Gaussian function, such as peak intensity and standard deviation, the size information of the light spot, such as its diameter or half-width at half-maximum, can be accurately determined, ensuring fitting accuracy when the light spot is close to a circle. Furthermore, selecting an appropriate fitting algorithm based on the ellipticity of the light spot allows for a more rational allocation of computational resources, ensuring improved overall computational efficiency while maintaining measurement accuracy.

[0042] In some embodiments, before determining the divergence angle of the diverging beam to be measured based on the actual displacements of the first and second positions and the first and second size information in S230, the method further includes: The displacements at the first and second positions are compensated and corrected using a real-time centroid offset detection mechanism and a temperature compensation model to obtain the actual displacements.

[0043] The real-time centroid shift detection mechanism continuously monitors changes in the centroid and compensates for displacement in real time during measurement, ensuring the stability of the measurement system under different operating conditions. Simultaneously, the temperature compensation model accurately calculates the displacement error caused by temperature changes based on real-time temperature data, combined with the material properties of the temperature sensor and the temperature-displacement relationship, and compensates for the displacement error. This allows the measurement system to adapt to temperature fluctuations and avoids significant fluctuations in measurement results due to temperature changes. For example, a honeycomb aluminum-based platform can be used to mount an active air-bearing vibration isolation system with a natural frequency not exceeding 2 Hz. Through the centroid shift resampling mechanism, the divergence angle measurement error caused by mechanical vibration can be suppressed within ±0.04 milliradians.

[0044] It should be noted that the laser divergence angle detection method based on differential measurement provided in this application embodiment and the laser divergence angle detection system based on differential measurement provided in this application embodiment are based on the same application concept. Therefore, the specific implementation of this embodiment can refer to the implementation of the aforementioned laser divergence angle detection system based on differential measurement, and the repeated parts will not be described again.

[0045] In some embodiments, the laser divergence angle detection device based on differential measurement provided in this application includes the laser divergence angle detection system based on differential measurement described above. Please refer to... Figure 3 The system comprises a laser source (310), a beam shaping module (320), a spot acquisition module (330), an area array detector (340), and a displacement feedback control module (350). The laser source (310) emits the divergent beam to be measured. The beam shaping module (320) performs preliminary collimation and shaping on the incident divergent beam, improving beam quality and reducing the divergence angle to make it closer to an ideal Gaussian beam. The displacement feedback control module (350) controls the position of the target screen in the spot acquisition module (330) through feedback adjustment. The target screen is moved to a first position along the laser axis, at which point the divergent beam is projected onto the target screen after propagation, forming a spot. The spot acquisition module (330) converts the spot signal on the target screen into a processable signal. The area array detector (340) receives the signal from the spot acquisition module and converts it into a spot image. The displacement feedback control module (350) then moves the target screen precisely from the first position to a second position. The laser beam continues to propagate and is projected onto a new position, forming a light spot. The light spot acquisition module 330 and the area array detector 340 operate again to acquire the light spot image at the second position. After acquiring the light spot images at both positions, the system extracts the size information of the light spot, such as its diameter or area, using image processing techniques. Simultaneously, the displacement feedback control module 350 provides the actual displacement between the two positions. Based on the principles of geometric optics, the divergence angle of the laser beam under test is calculated using the change in the light spot size at the two positions and the actual displacement.

[0046] In one optional embodiment, the displacement feedback control module is activated to drive the diffuse reflection target surface to move along the optical axis to the mechanical zero point. The reference position is calibrated using an absolute grating encoder, with a positioning error ≤ ±0.5μm. The beam shaping module pre-collimates the output beam of the semiconductor laser, ensuring the spot ellipticity is ≤ 0.15. The displacement feedback control module moves the target surface to Z1 = 50.000mm. The PID controller compensates for the backlash error in real time. After the target surface stabilizes, a 3ms delay is triggered, and the area array detector acquires the spot image. The geometric analysis processing module executes a hybrid fitting algorithm: if the spot ellipticity > 0.25, least squares elliptic fitting is used to calculate the 1 / e² energy envelope major axis diameter D1; if the spot ellipticity ≤ 0.25, a Gaussian model is used to calculate D1. The actual position coordinates, i.e., the displacement encoder feedback value Z1' = 50.002mm, are recorded. The displacement feedback control module moves ΔZ = 15.000 mm according to the command. During the movement, it monitors the ambient temperature change in real time and dynamically corrects the displacement based on the temperature sensor data, with a compensation coefficient of 0.15 μm / ℃. It eventually reaches position Z2' = 65.017 mm, locks the displacement platform, and triggers the vibration damping device to eliminate residual mechanical vibration. After a 3 ms delay, it acquires a light spot image at position Z2', calculates the equivalent diameter D2, and verifies that |D2-D1| ≥ 25 pixels. If the standard is not met, the above steps are automatically repeated. The change in light spot size measured over the known distance difference ΔZ is used to... By combining the geometric relationships of beam propagation, the divergence angle θ of the beam can be directly calculated. The core formula is based on: For small angle approximations, The pre-stored aberration compensation factor k_aber=0.92 is invoked, corresponding to a 50mm fused silica lens. The corrected divergence angle calculation formula is as follows: The reliability of the Gaussian distribution of θ value was tested. The display module renders the dual-position spot image and fitted curve in real time, and outputs the divergence angle measurement value θ=2.50mrad with an accuracy of ±0.02mrad. When the temperature drift causes the ΔZ deviation to be greater than 0.5μm, the system is automatically triggered to reinitialize.

[0047] This application also provides a computer-readable medium storing a computer program thereon, which, when executed by a processor, implements the aforementioned laser divergence angle detection method based on differential measurement. This computer-readable medium may be included in the device / apparatus / system described in the above embodiments; or it may exist independently and not assembled into that device / apparatus / system. The aforementioned computer-readable medium carries one or more programs, which, when executed, implement the method according to the embodiments of this application.

[0048] According to embodiments of this application, a computer-readable medium may be a computer-readable signal medium or a computer-readable storage medium, or any combination thereof. A computer-readable storage medium may be, for example, but not limited to, an electrical, magnetic, optical, electromagnetic, infrared, or semiconductor system, apparatus, or device, or any combination thereof. More specific examples of a computer-readable storage medium may include, but are not limited to: an electrical connection having one or more wires, a portable computer disk, a hard disk, random access memory (RAM), read-only memory (ROM), erasable programmable read-only memory (EPROM or flash memory), optical fiber, portable compact disk read-only memory (CD-ROM), optical storage device, magnetic storage device, or any suitable combination thereof. In this application, a computer-readable storage medium may be any tangible medium containing or storing a program that can be used by or in conjunction with an instruction execution system, apparatus, or device. In this application, a computer-readable signal medium may include a data signal propagated in baseband or as part of a carrier wave, carrying computer-readable program code. Such propagated data signals may take various forms, including but not limited to electromagnetic signals, optical signals, or any suitable combination thereof. Computer-readable signal media can also be any computer-readable medium other than computer-readable storage media, which can send, propagate, or transmit a program for use by or in connection with an instruction execution system, apparatus, or device. The program code contained on the computer-readable medium can be transmitted using any suitable medium, including but not limited to: wireless, wired, optical fiber, radio frequency signals, etc., or any suitable combination thereof.

[0049] Those skilled in the art will understand that the features described in the various embodiments and / or claims of this application can be combined and / or combined in various ways, even if such combinations or combinations are not explicitly described in this application. In particular, the features described in the various embodiments and / or claims of this application can be combined and / or combined in various ways without departing from the spirit and teachings of this application. All such combinations and / or combinations fall within the scope of this application. Therefore, the scope of this application should not be limited to the above embodiments, but should be defined not only by the appended claims, but also by their equivalents. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this invention should be included within the protection scope of this invention.

Claims

1. A laser divergence angle detection system based on differential measurement, characterized in that, include: The module consists of a displacement feedback control module, a spot acquisition module, and a geometric analysis processing module; among which, The displacement feedback control module is configured to move the optical screen target surface from a first position to a second position along the laser optical axis, and transmit the position information to the geometric analysis processing module; the position information includes the first position and the second position; The light spot acquisition module includes a laser source, a beam shaping module, an acquisition submodule, and an area array detector. The laser source generates a divergent beam to be tested. The beam shaping module is configured to perform preliminary collimation and shaping on the incident divergent beam to be tested. The acquisition submodule includes the light screen target surface and is configured to receive the divergent beam to be tested and convert it into a spatially distributed light spot signal. The area array detector is configured to convert the light spot signal into a light spot image. The geometric analysis processing module is configured to acquire the position information and the size information corresponding to the light spot image before and after the position adjustment, and to determine the divergence angle of the diverging beam to be tested based on the position information and the size information.

2. The laser divergence angle detection system based on differential measurement as described in claim 1, characterized in that, The displacement feedback control module includes a motion slide and a position encoder; When the motion slide receives a preset control command, it drives the platform with the fixed light screen target to move from a first position to a second position in the direction of the laser optical axis; the position encoder is configured to convert the position information corresponding to the first position and the second position into position information, and transmit the position information to the geometric analysis processing module.

3. The laser divergence angle detection system based on differential measurement as described in claim 1, characterized in that, The displacement feedback control module also includes a PID controller, a temperature sensor, and a vibration damping device; the PID controller is configured to compensate for the backlash error generated during the movement of the light screen target surface in real time, the temperature sensor is configured to monitor changes in ambient temperature and correct the position information based on the monitoring data, and the vibration damping device is configured to eliminate residual mechanical vibration.

4. The laser divergence angle detection system based on differential measurement as described in claim 1, characterized in that, The light spot acquisition module is fixed to the first adapter plate by screws, and the first adapter plate is connected to the first vertical motorized module. The beam shaping module is connected and installed on the left-right moving motorized module through an optomechanical connecting rod assembly. The area array detector is fixed to the second vertical motorized module through a second adapter plate and screws.

5. The laser divergence angle detection system based on differential measurement as described in claim 1, characterized in that, The light spot acquisition module is configured to acquire light spots after a preset delay following the stabilization of the target surface of the light screen.

6. A laser divergence angle detection method based on differential measurement, applied to the laser divergence angle detection system based on differential measurement as described in claims 1 to 5, characterized in that, include: The motion slide is controlled to move the light screen target surface from the first position to the second position; Acquire the light spot information generated by the divergent beam under test when it is at the first position and the second position on the target surface of the optical screen after propagation; The light spot information includes first size information corresponding to the first position and second size information corresponding to the second position; The divergence angle of the diverging beam to be measured is determined based on the actual displacements at the first and second positions, as well as the first and second size information.

7. The laser divergence angle detection method based on differential measurement as described in claim 6, characterized in that, The acquisition of the light spot information generated when the divergent beam under test is at the first and second positions on the target surface of the optical screen after propagation includes: A Gaussian-elliptic hybrid fitting algorithm is used to perform equivalent fitting on the non-ideal light spots at the first and second positions to determine the first size information of the non-ideal light spots at the first position and the second size information of the non-ideal light spots at the second position.

8. The laser divergence angle detection method based on differential measurement as described in claim 7, characterized in that, The step of using a Gaussian-elliptic hybrid fitting algorithm to perform equivalent fitting on the non-ideal light spots at the first and second positions includes: If the ellipticity of the non-ideal light spot is greater than the first threshold, the least squares ellipse fitting algorithm is used to perform an equivalent fitting on the non-ideal light spot. If the ellipticity of the non-ideal light spot is not greater than the first threshold, a Gaussian model is used to perform an equivalent fitting on the non-ideal light spot.

9. The laser divergence angle detection method based on differential measurement as described in claim 6, characterized in that, Before determining the divergence angle of the diverging beam to be measured based on the actual displacements of the first and second positions, as well as the first and second size information, the method further includes: The displacements at the first and second positions are compensated and corrected using a real-time centroid offset detection mechanism and a temperature compensation model to obtain the actual displacements.

10. A laser divergence angle detection device based on differential measurement, comprising the laser divergence angle detection system based on differential measurement as described in any one of claims 1 to 5.

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