Back-illuminated laser spatial filtering pinhole illumination monitoring system and method

Abstract

The application provides a back-illumination type laser spatial filtering pinhole illumination monitoring system and method, which comprises a spatial filter, an optical imaging module, an electric control system and a detector; the spatial filter, the optical imaging module and the detector are sequentially arranged on an outgoing light path of a laser light source to be measured, and the electric control system controls the spatial filter and the detector respectively, so that monitoring of the spatial filtering pinhole is realized, and the application can be used for collimation of a high-power laser light path.The back-illumination type laser spatial filtering pinhole illumination monitoring system and method have higher positioning accuracy than indirect illumination, and have higher safety in a high-power laser light path.In addition, the application adopts the principle of spatial filtering to eliminate the influence of stray light on the measuring system, and solves the problem of unclear small hole image by inserting an aperture diaphragm into a far-field imaging mirror.

Description

Technical Field

[0001] This invention relates to a high-power laser parameter measurement system and method, specifically to a back-illuminated high-power laser spatial filter pinhole illumination monitoring system and method. Background Technology

[0002] In the field of high-power laser parameter measurement, the measurement accuracy of far-field focal spot is required to be high. The factors affecting the measurement accuracy mainly include: (1) installation error of the measurement system; (2) collimation error of the light source; (3) error caused by detector tilt. Among them, the collimation error of the light source has a greater impact on the measurement accuracy of the focal spot and is not easy to control.

[0003] In the process of collimating a light source, a spatial filter is often used. The spatial filter is used to filter out stray light. The spatial filter contains a filter aperture and an illumination source. The illumination source provides illumination to the filter aperture. After passing through the optical system, the filter aperture is imaged on the detector. The center of the aperture is determined based on the position of the image. When the laser passes through the center of the aperture, the image formed on the detector is at the center of the imaging aperture. If the image is deviated, the incident angle of the laser needs to be adjusted so that the image formed by the high-power laser and the image formed by the aperture are on the same image plane, thus achieving collimation of the optical path.

[0004] The earliest relevant technology for the illumination monitoring system of the spatial filter aperture is found in: Cao Qiong, Yang Kuntao. Research on the application of spatial filtering technology in laser irradiation measurement system. Optics and Optoelectronics Technology, 2004, 2(6): 14~16; This article introduces the principle of spatial filtering and applies the technology to the detection of oil pipe diameter.

[0005] The existing problems can be roughly divided into two categories. The first category is the problem of the safe and reliable operation of the lighting source, and the second category is the problem of unclear pinhole imaging. Specifically: (1) The lighting source is located in the optical path system of a high-power laser and usually adopts the direct illumination or indirect illumination method. After working for a period of time, the lighting source is at risk of being damaged by strong laser or stray light. (2) At present, most of the imaging uses the scattered light from the pinhole end face. If the numerical aperture of the imaging beam is too large, it will cause large aberrations in the optical system, which will lead to blurry pinhole imaging. Summary of the Invention

[0006] The purpose of this invention is to solve the technical problems of safe and reliable operation of filtered pinhole illumination sources in high-power laser optical path systems, as well as the problem of unclear pinhole imaging in existing technologies. It provides a back-illuminated laser spatial filtering pinhole illumination monitoring system and method. By employing back-illumination, the illumination source is not in the optical path of the high-power laser, minimizing the risk of damage from the high-power laser and ensuring the safe and reliable operation of the illumination source. The principle of spatial filtering is used to eliminate the influence of stray light on the measurement system, and the problem of unclear pinhole images is solved by inserting an aperture stop inside the far-field imaging mirror.

[0007] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0008] A back-illuminated laser spatial filter pinhole illumination monitoring system is characterized by comprising a spatial filter, an optical imaging module, an electronic control system, and a detector; the spatial filter, optical imaging module, and detector are sequentially arranged in the output light path of the laser source under test, and the electronic control system controls the spatial filter and detector respectively;

[0009] The electronic control system includes a lighting control module, a network switch, a motor driver, a lighting drive module, a computer, and an electric translation stage. The network switch is connected to the detector, the lighting control module, and the motor driver. The lighting control module is connected to the lighting drive module and is used to control the lighting to turn on and off. The motor driver is connected to the electric translation stage and is used to drive and control the electric translation stage. The computer is connected to the network switch and controls the detector, the lighting control module, and the motor driver through the network switch.

[0010] The spatial filter includes filter apertures and an illumination source arranged sequentially along the optical path; the illumination source is back-illuminated; the illumination drive module is connected to the illumination source in the spatial filter; the electric translation stage is connected to the detector and is used to adjust the distance between the detector and the filter aperture in the spatial filter to achieve focusing of the detector.

[0011] Furthermore, the spatial filter includes an L1 lens, a filter aperture, an illumination source, and an L2 lens, which are sequentially arranged on the same optical path; the end face of the filter aperture is coplanar with the focal planes of the L1 lens and the L2 lens; the illumination source is driven by an illumination driving module.

[0012] Furthermore, the optical imaging module includes a far-field imaging mirror and an aperture stop; the laser light from the laser source under test is filtered by a spatial filter and then imaged by the far-field imaging mirror; the aperture stop is located at the front end of the detector and is used to limit the numerical aperture of the imaging beam.

[0013] Furthermore, the lighting control module includes a microcontroller module and a serial-to-network module; the microcontroller module consists of a microcontroller and peripheral circuits, which realizes the control of the lighting drive module, and the serial-to-network module is connected to the microcontroller module through a serial port; the serial-to-network module is connected to a network switch, which converts the serial communication protocol into a network communication protocol, so as to realize the computer's control of the lighting source.

[0014] Furthermore, the lighting source comprises a plurality of LEDs connected in series; a resistor is connected in parallel to each LED.

[0015] Furthermore, the lighting source is an ultraviolet LED, including LED beads and an LED board; the LED beads are resistively soldered onto the LED board, which is made of an aluminum substrate with a light-transmitting hole in the middle, and multiple LED beads are evenly arranged circumferentially around the light-transmitting hole on the LED board.

[0016] Furthermore, along the optical path, the laser first passes through the filter aperture (2002) and then through the light-transmitting aperture of the LED light board (401).

[0017] Furthermore, the output pin Vo+ of the lighting driver module is connected to the V+ of the lighting source, and the output pin Vo- of the lighting driver module is connected to the V- of the lighting source.

[0018] A back-illuminated laser spatial filter pinhole illumination monitoring method, employing the aforementioned back-illuminated laser spatial filter pinhole illumination monitoring system, is characterized by including the following steps:

[0019] Step 1: The computer (1005) issues a command to turn on the lighting, and the lighting control module receives the command and controls the lighting drive module to work.

[0020] Step 2: The lighting driver module provides driving current to the lighting source, which then emits light and illuminates the filter aperture.

[0021] Step 3: The filter aperture forms an image on the detector through the optical imaging module. The detector acquires images on the photosensitive surface of the detector in continuous working mode and displays them on the computer.

[0022] Step 4: Based on the clarity of the image formed by the filter aperture on the detector, adjust the distance between the detector and the optical imaging module using a motorized translation stage to obtain an image with a clear aperture edge.

[0023] Step 5: The laser source under test emits laser light. After passing through the spatial filter and optical imaging module, the laser light forms a far-field focal spot on the photosensitive surface of the detector.

[0024] Step 6: The detector acquires images of the filter aperture and the far-field focal spot. The emission angle of the laser source under test is adjusted according to the relative position of the filter aperture and the far-field focal spot to achieve optical path collimation. The far-field focal spot image data formed by the laser source under test on the detector after optical path collimation is transmitted to the computer through a network switch to complete the back-illuminated laser spatial filter aperture illumination monitoring.

[0025] Further, in step 1, the lighting control module receives instructions from the microcontroller module and controls the lighting drive module to work; the specific steps of the microcontroller module in performing the control are as follows:

[0026] Step 1.1: The microcontroller is powered on and initialized, and then waits to receive instructions from the computer.

[0027] Step 1.2: The microcontroller receives the instructions from the computer and makes a judgment.

[0028] Step 1.3, based on the judgment result, perform the following controls respectively:

[0029] If the command to turn on the lighting is detected, the corresponding I / O port is set to 1, and a response signal is sent to the computer.

[0030] If the command is identified as a command to turn off the lights, the corresponding I / O port is set to 0, and a response signal is sent to the computer.

[0031] If the command is identified as a query instruction, it initiates a query of the values ​​of the internal registers of each I / O port and provides the queried values ​​to the computer.

[0032] If the command is identified as a PWM dimming instruction, the PWM dimming program is started, and the corresponding I / O port generates a PWM signal to realize PWM dimming of the lighting source and generates a response signal to the computer.

[0033] Step 1.4: Complete the instruction and the program returns to the state of waiting to receive instructions.

[0034] Compared with the prior art, the present invention has the following beneficial technical effects:

[0035] 1. This invention adopts a back-illuminated lighting method, in which the lighting source is not in the laser light path, avoiding the risk of the lighting source being damaged by a strong laser and ensuring the safety of the lighting source. At the same time, the hardware circuit design of the LED light board can ensure that the lighting source can continue to function even if a single LED is damaged, so as not to cause the lighting function to fail, thus improving the reliability of the system.

[0036] 2. This invention uses the principle of spatial filtering to eliminate the influence of stray light on the measurement system. It solves the problem of unclear pinhole imaging by inserting an aperture stop inside the far-field imaging mirror. Based on the imaging position of the filtered pinhole, the center position of the laser spot is determined, providing a basis for laser collimation, thereby improving the measurement accuracy of the entire monitoring system.

[0037] 3. This invention improves the performance of the monitoring system and reduces maintenance costs. Attached Figure Description

[0038] Figure 1 This is a schematic diagram of the back-illuminated high-power laser spatial filter pinhole illumination monitoring system of the present invention.

[0039] Figure 2 This is a block diagram illustrating the principle of the spatial filter and optical imaging module in an embodiment of the back-illuminated high-power laser spatial filter pinhole illumination monitoring system of the present invention.

[0040] Figure 3 This is a schematic diagram of the LED light source in an embodiment of the present invention;

[0041] Figure 4 This is a layout diagram of the LED light source in an embodiment of the present invention;

[0042] Figure 5 This is a diagram showing the connection relationship between the lighting drive module and the lighting source in an embodiment of the present invention;

[0043] Figures 6(a), 6(b), and 6(c) are schematic diagrams illustrating the principles of front illumination, indirect illumination, and back illumination of the LED light panel in the embodiments of the present invention, respectively.

[0044] Figure 7 This is a schematic block diagram of the lighting control module in an embodiment of the present invention;

[0045] Figure 8 This is a schematic diagram of the workflow of an embodiment of the back-illuminated high-power laser spatial filtering pinhole illumination monitoring method of the present invention;

[0046] Figure 9 This is a schematic diagram of the microcontroller control flow in step 1 of an embodiment of the back-illuminated high-power laser spatial filtering pinhole illumination monitoring method of the present invention;

[0047] Figure 10(a) is an imaging effect diagram obtained by using indirect illumination in an embodiment of the present invention;

[0048] Figure 10(b) is an imaging effect diagram obtained by using back-illuminated (without aperture stop) illumination method in an embodiment of the present invention;

[0049] Figure 10(c) is an imaging effect diagram obtained by using back-illuminated (with added aperture stop) illumination method in an embodiment of the present invention;

[0050] Figure 11 This is a diagram illustrating the effect of using an indirect lighting method for the illumination source in an embodiment of the present invention.

[0051] The annotations in the attached figures are explained as follows:

[0052] 100-Electrical control system, 101-Laser source, 102-Spatial filter, 103-Optical imaging module, 104-Detector, 1001-Lighting control module, 1002-Network switch, 1003-Motor driver, 1004-Lighting drive module, 1005-Computer, 1006-Electric translation stage, 2001-L1 lens, 2002-Filter aperture, 2003-Lighting source, 2004-L2 lens, 201-Far-field imaging mirror, 202-Aperture stop, 301-Resistor, 302-LED, 401-LED light board, 402-LED beads, 9001-Microcontroller module, 9002-Serial to network module. Detailed Implementation

[0053] To make the objectives, advantages, and features of the present invention clearer, the back-illuminated laser spatial filter pinhole illumination monitoring system and method proposed in this invention will be further described in detail below with reference to the accompanying drawings and specific embodiments. Those skilled in the art should understand that these embodiments are merely used to explain the technical principles of the present invention and are not intended to limit the scope of protection of the present invention.

[0054] like Figure 1 , Figure 2 As shown, the present invention relates to a back-illuminated laser spatial filter pinhole illumination monitoring system, comprising a spatial filter 102, an optical imaging module 103, an electronic control system 100, a detector 104, an L1 lens 2001, a filter pinhole 2002, an illumination source 2003, and an L2 lens 2004. The spatial filter 102 is composed of the L1 lens 2001, the L2 lens 2004, the filter pinhole 2002, and the illumination source 2003. The optical imaging module 103 includes a far-field imaging mirror 201 and an aperture stop 202. The spatial filter 102, the optical imaging module 103, and the detector 104 are sequentially arranged in the output optical path of the laser source 101 under test, wherein the laser source 101, the spatial filter 102, the optical imaging module 103, and the detector 104 remain coaxial throughout the optical path.

[0055] In this invention, the laser source, with a wavelength of 351 nm, is used as the laser under test. After passing through the spatial filter 102 and the optical imaging module 103, it forms a far-field focal spot image on the detector 104. The working principle of the above optical system is as follows: the end face of the filter aperture 2002 is coplanar with the focal planes of the L1 lens 2001 and the L2 lens 2004. The illumination source 2003 is located behind the filter aperture 2002, and the conical light emitted by it illuminates the end face of the aperture. The scattered light from the end face passes through the L2 lens 2004 and the far-field imaging mirror 201, forming a pinhole image on the target surface of the detector 104. The aperture stop 202 in front of the detector 104 is used to limit the numerical aperture of the imaging beam. After the laser is filtered by the spatial filter 102, the far-field focal spot is obtained by the far-field imaging mirror 201. By comparing the position of the far-field focal spot relative to the pinhole image, the laser aperture deviation can be determined. The detector 104 is used to collect the image formed by the filter aperture 2002 and the high-intensity laser on the photosensitive surface of the detector 104, providing test data for optical path collimation and focal spot measurement.

[0056] In this system, the spatial filter 102 is used to filter out high-frequency stray light. The size of its filter aperture 2002 is usually calculated based on the required cutoff frequency of the spatial filter 102. The ratio of the focal lengths of the L1 lens 2001 and the L2 lens 2004 is determined based on the beam-shrinking ratio of the spatial filter 102. The value of the focal length and the size of the filter aperture 2002 together determine the magnitude of the cutoff frequency. To monitor the position of the laser at the aperture 2002, it is necessary to simultaneously image the laser focal spot and the inner circle of the filter aperture 2002. The L2 lens 2004 and the far-field imaging mirror 201 constitute an imaging system. The target surface of the detector 104 is located at the focal plane of the far-field imaging mirror, and the laser focal spot and the inner circle of the aperture are imaged simultaneously. Let the diameter of the filter aperture 2002 be d, the focal length of the L2 lens 2004 be f1, and the focal length of the far-field imaging mirror 201 be f2, then the inner edge diameter of the aperture image is d×f2 / f1. The diameter of the aperture affects the width of the bright ring band in the pinhole image. Choosing a diameter not smaller than the filter aperture ensures that the ring band width is greater than zero. The imaging quality of the far-field pinhole is improved by reducing the numerical aperture of the imaging beam; therefore, an aperture stop 202 is added after the far-field imaging mirror 201. The aperture stop 202 should be positioned as close as possible to the far-field imaging mirror 201, and its size should be as large as possible while still meeting image quality requirements.

[0057] The electronic control system 100 is used to drive and control the lighting source 2003, control the movement of the electric translation stage, control the acquisition of the detector 104, and display and process the image of the filter aperture 2002. In this invention, the electronic control system 100 includes a lighting control module 1001, a network switch 1002, a motor driver 1003, a lighting drive module 1004, a computer 1005, and an electric translation stage 1006. The lighting drive module 1004 drives the lighting source 2003, providing a stable current to it. The lighting control module 1001 controls the lighting on and off, adjusts the driving current, and thus controls the brightness of the lighting. The network switch 1002 enables network communication between the computer 1005, the detector 104, the lighting control module 1001, and the motor driver 1003. The computer 105 acts as the central control device, controlling the detector 104, the lighting control module 1001, and the motor driver 1003. The motor driver 1003 is used to drive and control the electric translation stage 1006, which carries the detector 104 and is used to adjust the position of the detector 104 and the filter aperture 2002 to achieve focusing of the detector 104.

[0058] like Figure 3 , Figure 4 As shown, the lighting source of this invention uses ultraviolet LEDs, and the hardware circuit uses multiple LEDs connected in series, with a resistor 301 connected in parallel to each LED 302. The advantage of this design is that when an LED has an open-circuit fault, the current flows through the resistor connected in parallel, without affecting the operation of other LEDs; when an LED has a short-circuit fault, other LEDs can continue to work, preventing the overall failure of the lighting source, thus improving the reliability of the system. The number of LED beads 402 is determined by the brightness and uniformity of the image formed on the detector 104, and the voltage between V+ and V- is the sum of the voltage drops across each LED. The LED beads 402 and the resistor 301 are soldered onto the LED light board 401, which uses an aluminum substrate. Multiple LED beads 402 are evenly arranged around a ring. To fully utilize the heat dissipation area without increasing costs, the LED light board 401 adopts an outer square and inner circle design.

[0059] The following is a specific embodiment of the lighting source: The wavelength of the lighting source is 365nm, the LED light source model is VLMU1610-365-135, and the manufacturer is VISHAY Semiconductor. The voltage drop of a single LED is 3.5V, the current flowing through the LED is 1mA, and the LED current range is 0~60mA. The maximum radiant power of a single LED is 26mW. The hardware circuit uses 8 LEDs connected in series, with a 10Kohm resistor connected in parallel with each LED. The voltage of the 8 LEDs connected in series is 28V.

[0060] Figures 6(a), 6(b), and 6(c) illustrate the principles of front-illuminated, indirect-illuminated, and back-illuminated LED light panels. To prevent damage from strong lasers, this invention employs a back-illuminated design. The front-illuminated design, as shown in Figure 6(a), involves the LED light panel 401 positioned between the laser source 101 and the filter aperture 2002. The LED beads 402 face the filter aperture 2002, which has a diameter of 10mm. The inner diameter of the LED light panel 401 is 12mm, and the LED beads 402 are evenly arranged around a circle with a diameter of 18.6mm. When the LED illumination is turned on, the edge of the filter aperture is illuminated by the divergence angle, and the aperture is imaged on the detector through the optical system. The disadvantage of the front-illuminated design is that the LED source is easily damaged by the laser source. Specifically, during calibration, the laser may deviate from the center of the aperture and strike the filter aperture plate. After reflection from the filter aperture plate, this could damage the LED light panel.

[0061] As shown in Figure 6(b), the indirect method is as follows: the LED light board 404 is located to the right of the filter aperture 2002. The LED beads 402 are directly imaged on the detector 104 through the optical system. The position of the aperture center is indirectly determined based on the position of the LED beads 402. The disadvantages of the indirect method are: 1) the center position of the aperture is not accurately determined; 2) it is easily damaged by the reflected laser, resulting in the failure of the light board and the failure of the lighting function.

[0062] Because both of the above methods have some drawbacks, in this embodiment of the invention, a back-illuminated method is adopted, as shown in Figure 6(c): the LED light board 401 is on the right side of the filter aperture 2002, the LED beads 402 face away from the optical system, the aperture diameter is 10mm, the inner diameter of the LED light board 401 is 12mm, and the LED beads 402 are evenly arranged in a circle with a diameter of 18.6mm. After the LED illumination is turned on, the edge of the filter aperture 2002 is illuminated by the divergence angle of the LED light source, and the aperture is imaged on the detector 104 through the optical system. The advantage of the back-illuminated method is that it can avoid the illumination source being damaged by the laser, and can directly illuminate the edge of the aperture, and the center position of the aperture can be evaluated by the position of the edge of the aperture on the detector.

[0063] like Figure 5As shown in the example of this invention, the hardware circuit of the lighting driver module 1004 uses TI's TPS61161A as the LED constant current driver chip. The circuit operates in boost mode at a frequency of 600kHz, which can further reduce output ripple, improve converter efficiency, and allow the use of fewer external components. The circuit has open-circuit protection and a reserved external interface for current regulation, which can control the output current through the input PWM signal. The external interfaces of the circuit include: VI+, VI-, Vo+, Vo-, and DIM. The input ports are VI+, VI-, and DIM, and the output ports are Vo+ and Vo-. The input voltage range is 2.7V~18V, and the voltage open-circuit protection point is 38V; DIM is the current regulation port. The output pin Vo+ of the lighting driver module 1004 is connected to the V+ of the lighting source 2003, and the output pin Vo- of the lighting driver module 1004 is connected to the V- of the lighting source 2003.

[0064] like Figure 7 As shown, the lighting control module 1001 consists of a microcontroller module 9001 and a serial-to-network module 9002. The microcontroller module 9001, composed of a microcontroller and peripheral circuits, is used to control the lighting of the lighting drive module 1004. The serial-to-network module 9002 converts the serial communication protocol to a network communication protocol, enabling the computer 105 to control the lighting source 2003. The interface between the serial-to-network module 9002 and the microcontroller module 9001 is a serial port.

[0065] like Figure 8 — Figure 9 As shown, the present invention also provides a monitoring method for a back-illuminated laser spatial filter pinhole illumination monitoring system, comprising the following steps:

[0066] Step 1: The computer 1005 issues a command to turn on the lighting, and the lighting control module 1001 receives the command and controls the lighting drive module 1004 to work.

[0067] Step 2: The lighting drive module 1004 provides drive current to the lighting source 2003, and the lighting source 2003 emits light and illuminates the filter aperture 2002;

[0068] Step 3: The filter aperture 2002 is imaged on the detector 104 through the optical imaging module 103. The detector 104 acquires images on the photosensitive surface of the detector in continuous working mode and displays them through the computer 1005.

[0069] Step 4: Based on the clarity of the image formed by the filter aperture 2002 on the detector 104, adjust the distance between the detector 104 and the optical imaging module 103 using the electric translation stage 1006 to obtain an image with a clear aperture edge.

[0070] Step 5: The laser source 101 under test emits a laser. After passing through the spatial filter 102 and the optical imaging module 103, the laser image is formed on the photosensitive surface of the detector 104 to form a far-field focal spot.

[0071] Step 6: The detector 104 acquires images of the filter aperture 2002 and the far-field focal spot. Based on the relative positions of the filter aperture 2002 and the far-field focal spot, the emission angle of the laser source 101 under test is adjusted to achieve optical path collimation. The far-field focal spot image data formed by the laser source 101 under test on the detector 104 after optical path collimation is transmitted to the computer 1005 through the network switch 1002 to complete the back-illuminated laser spatial filter aperture illumination monitoring.

[0072] The specific steps for controlling the microcontroller module 9001 in step 1 are as follows:

[0073] Step 1.1: The microcontroller is powered on and initialized, and waits to receive instructions from the computer (1005).

[0074] Step 1.2: The microcontroller receives the instruction from the computer 1005 and makes a judgment.

[0075] Step 1.3, based on the judgment result, perform the following controls respectively:

[0076] If the command to turn on the lighting is detected, the corresponding I / O port is set to 1, and a response signal is sent to computer 1005.

[0077] If the command is identified as a command to turn off the lights, the corresponding I / O port is set to 0, and a response signal is sent to computer 1005.

[0078] If the command is identified as a query instruction, it initiates a query of the values ​​of the internal registers of each I / O port and provides the queried values ​​to computer 1005.

[0079] If the command is identified as a PWM dimming instruction, the PWM dimming program is started. The corresponding I / O port generates a PWM signal to achieve PWM dimming of the lighting source and generates a response signal to the computer 1005.

[0080] Step 1.4: Complete the instruction and the program returns to the state of waiting to receive instructions.

[0081] Figure 10(a) shows the imaging effect obtained using indirect illumination, and Figure 10(b) shows the imaging effect obtained using back-illuminated illumination (without an aperture stop). A comparison of the two figures shows that, because indirect illumination relies on the position of the LED beads to indirectly determine the center position of the aperture, its positioning accuracy is slightly lower than that of back-illuminated illumination. Figure 10(c) shows the imaging effect obtained using back-illuminated illumination (with an aperture stop of 10mm diameter). The inner diameter of the bright ring corresponds to the filter aperture 2002, and the outer diameter corresponds to the inner diameter of the LED light source 401. Theoretically, the inner diameter of the bright ring should be 3.29mm, and the outer diameter should be 3.95mm. By adjusting the relative position of the aperture stop 202 and the detector 104, the inner diameter of the bright ring is found to be between 3.03 and 3.35mm, and the outer diameter between 3.9mm and 4.05mm, thus obtaining values ​​closer to the theoretical values. Without the aperture stop 202, more stray light enters, resulting in a smaller inner diameter of the bright ring and less clear edges.

[0082] like Figure 11 As shown in the figure, in an indirect lighting method, two LED beads in the lighting source are damaged by a laser. This figure illustrates two points: 1) In an indirect lighting method, the lighting source is susceptible to damage from a high-power laser. However, in a back-illuminated lighting method, since the lighting source is not in the path of the high-power laser, the risk of damage from a high-power laser is minimized, ensuring the stable and reliable operation of the lighting source; 2) Because the lighting source uses a series connection of LED beads and a parallel connection of resistors, even if a single LED experiences an open-circuit fault, the other LEDs can still work normally, preventing the overall failure of the lighting source. This is also a characteristic of lighting sources.

[0083] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit them. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the present invention.

Claims

1. A back-illuminated laser spatial filter pinhole illumination monitoring system, characterized in that: It includes a spatial filter (102), an optical imaging module (103), an electronic control system (100), and a detector (104); the spatial filter (102), the optical imaging module (103), and the detector (104) are sequentially arranged in the output light path of the laser source (101) under test, and the electronic control system (100) controls the spatial filter (102) and the detector (104) respectively; The electronic control system (100) includes a lighting control module (1001), a network switch (1002), a motor driver (1003), a lighting drive module (1004), a computer (1005), and an electric translation stage (1006). The network switch (1002) is connected to the detector (104), the lighting control module (1001), and the motor driver (1003). The lighting control module (1001) is connected to the lighting drive module (1004) and is used to control the lighting to turn on and off. The motor driver (1003) is connected to the electric translation stage (1006) and is used to drive and control the electric translation stage (1006). The computer (1005) is connected to the network switch (1002) and controls the detector (104), the lighting control module (1001), and the motor driver (1003) through the network switch (1002). The spatial filter (102) includes a filter aperture (2002) and an illumination source (2003) arranged sequentially along the optical path; the illumination source (2003) is back-illuminated; the illumination driving module (1004) is connected to the illumination source (2003) in the spatial filter (102); the electric translation stage (1006) is connected to the detector (104) and is used to adjust the distance between the detector (104) and the filter aperture (2002) in the spatial filter (102) to achieve focusing of the detector (104).

2. The back-illuminated laser spatial filter pinhole illumination monitoring system according to claim 1, characterized in that: The spatial filter includes an L1 lens (2001), a filter aperture (2002), an illumination source (2003), and an L2 lens (2004) arranged sequentially on the same optical path; the end face of the filter aperture (2002) is coplanar with the focal planes of the L1 lens (2001) and the L2 lens (2004); the illumination source (2003) is driven by an illumination driving module (1004).

3. The back-illuminated laser spatial filter pinhole illumination monitoring system according to claim 2, characterized in that: The optical imaging module (103) includes a far-field imaging mirror (201) and an aperture stop (202); the laser light from the laser source (101) under test is filtered by the spatial filter (102) and then imaged by the far-field imaging mirror (201); the aperture stop (202) is set at the front end of the detector (104) to limit the numerical aperture of the imaging beam.

4. The back-illuminated laser spatial filter pinhole illumination monitoring system according to claim 1, 2, or 3, characterized in that: The lighting control module (1001) includes a microcontroller module (9001) and a serial-to-network module (9002). The microcontroller module (9001) consists of a microcontroller and peripheral circuits, which realizes the control of the lighting drive module (1004). The serial-to-network module (9002) is connected to the microcontroller module (9001) through a serial port. The serial-to-network module (9002) is connected to the network switch (1002) to convert the serial communication protocol into a network communication protocol, so as to realize the control of the lighting source (2003) by the computer (1005).

5. The back-illuminated laser spatial filter pinhole illumination monitoring system according to claim 4, characterized in that: The lighting source (2003) includes a plurality of LEDs (302) connected in series; a resistor (301) is connected in parallel to each LED (302).

6. The back-illuminated laser spatial filter pinhole illumination monitoring system according to claim 5, characterized in that: The lighting source (2003) is an ultraviolet LED, including LED beads (402) and LED board (401); resistor (301) is soldered on LED board (401), LED board (401) is made of aluminum substrate, with a light-transmitting hole in the middle, and multiple LED beads (402) are evenly arranged on LED board (401) around the light-transmitting hole in the circumferential direction.

7. The back-illuminated laser spatial filter pinhole illumination monitoring system according to claim 6, characterized in that: The LED light board (401) is backlit. Along the light path, the laser first passes through the filter aperture (2002) and then through the light-transmitting aperture of the LED light board (401).

8. The back-illuminated laser spatial filter pinhole illumination monitoring system according to claim 7, characterized in that: The output pin Vo+ of the lighting driver module (1004) is connected to the V+ of the lighting source (2003), and the output pin Vo- of the lighting driver module (1004) is connected to the V- of the lighting source (2003).

9. A method for monitoring pinhole illumination using a back-illuminated laser spatial filter, employing the back-illuminated laser spatial filter pinhole illumination monitoring system as described in any one of claims 1-8, characterized in that... Includes the following steps: Step 1: The computer (1005) issues a command to turn on the lighting, and the lighting control module (1001) receives the command and controls the lighting drive module (1004) to work. Step 2: The lighting driving module (1004) provides driving current to the lighting source (2003), and the lighting source (2003) emits light and illuminates the filter aperture (2002). Step 3: The filter aperture (2002) is imaged on the detector (104) through the optical imaging module (103). The detector (104) acquires the image on the photosensitive surface of the detector in continuous working mode and displays it through the computer (1005). Step 4: Based on the clarity of the image formed by the filter aperture (2002) on the detector (104), adjust the distance between the detector (104) and the optical imaging module (103) using the electric translation stage (1006) to obtain an image with a clear aperture edge. Step 5: The laser source under test (101) emits laser light. After passing through the spatial filter (102) and the optical imaging module (103), the laser light forms a far-field focal spot on the photosensitive surface of the detector (104). Step 6: The detector (104) acquires images of the filter aperture (2002) and the far-field focal spot. The emission angle of the laser source under test (101) is adjusted according to the relative position of the filter aperture (2002) and the far-field focal spot to achieve optical path collimation. The far-field focal spot image data formed by the laser source under test (101) on the detector (104) after optical path collimation is transmitted to the computer (1005) through the network switch (1002) to complete the back-illuminated laser spatial filter aperture illumination monitoring.

10. The back-illuminated laser spatial filter pinhole illumination monitoring method according to claim 9, characterized in that: In step 1, the lighting control module (1001) receives instructions from the microcontroller module (9001) and controls the lighting drive module (1004) to work; the specific steps of the microcontroller module (9001) in performing the control are as follows: Step 1.1: The microcontroller is powered on and initialized, and waits to receive instructions from the computer (1005). Step 1.2: The microcontroller receives the instruction from the computer (1005) and makes a judgment; Step 1.3, based on the judgment result, perform the following controls respectively: If the command is identified as an instruction to turn on the lighting, the corresponding I / O port is set to 1 and a response signal is sent to the computer (1005). If the command is determined to be a command to turn off the lighting, the corresponding I / O port is set to 0 and a response signal is sent to the computer (1005). If the command is identified as a query status instruction, it initiates a query of the values ​​of the internal registers of each I / O port and provides the queried values ​​to the computer (1005). If the command is identified as a PWM dimming instruction, the PWM dimming program is started, and the corresponding IO port generates a PWM signal to realize PWM dimming of the lighting source and generates a response signal to the computer (1005). Step 1.4: Complete the instruction and the program returns to the state of waiting to receive instructions.

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