Backside illumination-based laser spatial filtering pinhole illumination monitoring system and method

Abstract

The invention provides a back-illuminated laser spatial filtering pinhole illumination monitoring system and method. The system 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 emergent light path of the to-be-measured laser light source, the electronic control system controls the spatial filter and the detector respectively, so that the spatial filtering small hole is monitored, and the device and the method can be used for collimation of a high-power laser light path. Compared with indirect illumination, the back-illuminated laser spatial filtering aperture illumination monitoring system and method have the advantages that back-illuminated illumination has higher positioning accuracy, and higher safety is achieved in a high-power laser light path. Besides, the principle of spatial filtering is adopted, the influence of stray light on a measurement system is eliminated, and the problem that a pinhole image is not clear is solved by inserting an aperture diaphragm into the far-field imaging mirror.

Description

Technical Field

[0001] The present invention relates to a high-power laser parameter measurement system and method, and in particular to a back-illuminated high-power laser spatial filtering pinhole illumination monitoring system and method. Background Art

[0002] In the field of high-power laser parameter measurement, high measurement accuracy is required for the far-field focal spot. The factors affecting the measurement accuracy mainly include: (1) the installation error of the measurement system; (2) the collimation error of the light source; and (3) the error caused by the tilt of the detector. Among them, the collimation error of the light source has a greater impact on the focal spot measurement accuracy and is difficult to control.

[0003] In the process of collimating the light source, spatial filters are often used. Spatial filters are used to filter out stray light. The spatial filter is equipped with a filter hole and an illumination light source. The illumination light source provides illumination for the filter hole. The filter hole is imaged on the detector after passing through the optical system. The center of the hole is determined according to the position of the imaging. When the laser passes through the center of the hole, the image formed on the detector is at the center of the imaging hole. If the imaging deviates, it is necessary to adjust the incident angle of the laser so that the image formed by the high-power laser and the image formed by the hole are on the same image plane, thereby achieving collimation of the light path.

[0004] For the spatial filtering pinhole illumination monitoring system, the related technology was first seen 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 document introduces the principle of spatial filtering and uses this technology in the detection of oil pipe diameter.

[0005] The existing problems can be roughly divided into two categories. The first category is the problem of safe and reliable operation of the lighting source, and the other category is the problem of unclear pinhole imaging. The details are as follows: (1) The lighting source is in the optical path system of the high-power laser, and usually adopts direct illumination or indirect illumination. 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 scattered light from the end face of the pinhole. If the numerical aperture of the imaging beam is too large, it will cause large aberrations in the optical system, which will lead to blurred pinhole imaging. Summary of the invention

[0006] The purpose of the present invention is to solve the technical problems of the prior art in that the filtered pinhole illumination light source works safely and reliably in the high-power laser optical path system, as well as the technical problem of unclear pinhole imaging, and to provide a back-illuminated laser spatial filtering pinhole illumination monitoring system and method. By adopting the back-illuminated illumination method, the illumination light source is not in the optical path of the high-power laser, which avoids the risk of damage by the high-power laser to the greatest extent and ensures the safe and reliable operation of the illumination light source. The principle of spatial filtering is adopted to eliminate the influence of stray light on the measurement system, and the problem of unclear pinhole image is solved by inserting an aperture stop in the far-field imaging mirror. To achieve the above purpose, the technical solution adopted by the present invention is as follows:

[0007] A back-illuminated laser spatial filtering pinhole illumination monitoring system, which is special in that it includes 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 the outgoing light path of the laser light source to be measured, and the electric control system controls the spatial filter and the detector respectively;

[0008] The electric 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 respectively connected to the detector, the lighting control module and the electric drive, the lighting control module is connected to the lighting drive module, and is used to control the on and off of the lighting; 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 the detector, the lighting control module and the motor driver are respectively controlled through the network switch;

[0009] The spatial filter comprises filter pinholes and an illumination light source sequentially arranged along an optical path; the illumination light source is back-illuminated; the illumination driving module is connected to the illumination light 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 pinhole in the spatial filter to achieve focusing of the detector.

[0010] Furthermore, the spatial filter comprises an L1 lens, the filter pinhole, the illumination light source, and an L2 lens which are sequentially arranged on the same optical path; the end face of the filter pinhole is coplanar with the focal planes of the L1 lens and the L2 lens; and the illumination light source is driven by an illumination driving module.

[0011] Furthermore, the optical imaging module includes a far-field imaging mirror and an aperture diaphragm; the laser of the laser light source to be measured is filtered by a spatial filter and then imaged by the far-field imaging mirror; the aperture diaphragm is arranged at the front end of the detector to limit the numerical aperture of the imaging beam.

[0012] Furthermore, the lighting control module includes a single-chip microcomputer module and a serial port to network module; the single-chip microcomputer module is composed of a single-chip microcomputer and peripheral circuits to realize the control of the lighting drive module, and the serial port to network module is connected to the single-chip microcomputer module through a serial port; the serial port to network module is connected to the network switch to convert the serial port communication protocol into a network communication protocol to realize the computer's control of the lighting source.

[0013] Furthermore, the lighting source includes a plurality of LEDs connected in series; each LED is connected in parallel with a resistor.

[0014] Furthermore, the lighting source is an ultraviolet LED, including LED lamp beads and an LED light board; the resistor is welded on the LED light board, the LED light board adopts an aluminum substrate, a light-through hole is provided in the middle, and multiple LED lamp beads are evenly arranged on the LED light board along the circumference around the light-through hole.

[0015] Furthermore, along the optical path, the laser first passes through the filter aperture (2002) and then passes through the light-transmitting hole of the LED light board (401).

[0016] Furthermore, the output pin Vo+ of the lighting driving module is connected to V+ of the lighting light source, and the output pin Vo- of the lighting driving module is connected to V- of the lighting light source.

[0017] A back-illuminated laser spatial filter pinhole illumination monitoring method is provided, which adopts the back-illuminated laser spatial filter pinhole illumination monitoring system, and is special in that it comprises the following steps:

[0018] 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 driving module to work;

[0019] Step 2, the lighting driving module provides a driving current to the lighting light source, and the lighting light source emits light and illuminates the filter aperture;

[0020] Step 3, the filter pinhole is imaged on the detector through the optical imaging module, and the detector is in a continuous working mode, collecting the image on the photosensitive surface of the detector and displaying it on the computer;

[0021] Step 4, according to the clarity of the image of the filter pinhole on the detector, the distance between the detector and the optical imaging module is adjusted by the electric translation stage to obtain a clear image of the edge of the pinhole;

[0022] Step 5, the laser light source to be tested emits laser light, and after the laser light passes through the spatial filter and the optical imaging module, it is imaged on the photosensitive surface of the detector to form a far-field focal spot;

[0023] Step 6: The detector collects the filter pinhole and far-field focal spot images, adjusts the emission angle of the laser light source to be tested according to the relative positions of the filter pinhole and the far-field focal spot, realizes the collimation of the light path, and transmits the far-field focal spot image data formed by the laser light source to be tested on the detector after the light path is collimated to the computer through the network switch to complete the back-illuminated laser spatial filter pinhole illumination monitoring.

[0024] Furthermore, in step 1, the lighting control module receives instructions through the single-chip microcomputer module and controls the lighting driving module to work; the specific steps of the single-chip microcomputer module to perform control are:

[0025] Step 1.1, the microcontroller is powered on and initialized and waits for receiving computer instructions;

[0026] Step 1.2, the single chip microcomputer receives the instruction sent by the computer and makes a judgment;

[0027] Step 1.3: According to the judgment results, perform the following controls respectively:

[0028] If it is judged as a lighting-on instruction, the corresponding IO port is set to 1 and a response signal is sent to the computer;

[0029] If it is judged as a command to turn off the lighting, the corresponding IO port is set to 0 and a response signal is sent to the computer;

[0030] It is judged as a query status instruction, and the query value of the internal register of each IO port is started, and the query value is provided to the computer;

[0031] It is judged as a PWM dimming instruction, the PWM dimming program is started, the corresponding IO port generates a PWM signal, realizes the PWM dimming of the lighting source, and generates a response signal to the computer;

[0032] Step 1.4, complete the instruction, and the program returns to the state of waiting to receive instructions.

[0033] Compared with the prior art, the present invention has the following beneficial technical effects:

[0034] 1. The present invention adopts a back-illuminated lighting method. The lighting source is not in the laser light path, avoiding the risk of the lighting source being damaged by a strong laser, thereby 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 lamp bead is damaged, thereby not causing the lighting function to fail, thereby improving the reliability of the system.

[0035] 2. The present invention adopts the principle of spatial filtering to eliminate the influence of stray light on the measurement system. The problem of unclear pinhole imaging is solved by inserting an aperture stop in the far-field imaging mirror. The center position of the laser spot is determined according to the imaging position of the filter pinhole, which provides a basis for the collimation of the laser, thereby improving the measurement accuracy of the entire monitoring system;

[0036] 3. The present invention improves the performance of the monitoring system and reduces the maintenance cost. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] Figure 1 This is a principle block diagram of the back-illuminated high-power laser spatial filtering pinhole illumination monitoring system of the present invention;

[0038] Figure 2 It is a principle block diagram of a spatial filter and an optical imaging module in an embodiment of the back-illuminated high-power laser spatial filtering pinhole illumination monitoring system of the present invention;

[0039] Figure 3 This is a schematic diagram of the LED light source in an embodiment of the present invention;

[0040] Figure 4 This is a layout diagram of an LED light source in an embodiment of the present invention;

[0041] Figure 5 A diagram showing the connection relationship between the lighting driving module and the lighting light source in an embodiment of the present invention;

[0042] 6(a), 6(b), and 6(c) are schematic diagrams showing the principles of the LED light panels in the embodiments of the present invention using front illumination, indirect illumination, and back illumination, respectively;

[0043] Figure 7 is a principle block diagram of a lighting control module in an embodiment of the present invention;

[0044] Figure 8 It is a schematic diagram of the working process of an embodiment of the back-illuminated high-power laser spatial filtering pinhole illumination monitoring method of the present invention;

[0045] Fig. 9 It is a schematic diagram of the single chip microcomputer 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;

[0046] FIG10( a ) is an imaging effect diagram obtained by using an indirect lighting method according to an embodiment of the present invention;

[0047] FIG10( b ) is an imaging effect diagram obtained by adopting a back-illuminated (without an aperture stop) illumination method according to an embodiment of the present invention;

[0048] FIG10( c ) is an imaging effect diagram obtained by adopting a back-illuminated (adding an aperture stop) illumination method according to an embodiment of the present invention;

[0049] Fig.11 This is a rendering of the lighting effect of an indirect lighting method using an embodiment of the present invention;

[0050] The following are the descriptions of the reference numerals:

[0051] 100-electric control system, 101-laser light source, 102-spatial filter, 103-optical imaging module, 104-detector, 1001-illumination control module, 1002-network switch, 1003-electric driver, 1004-illumination driver module, 1005-computer, 1006-electric translation stage, 2001-L1 lens, 2002-filter pinhole, 2003-illumination light source, 2004-L2 lens, 201-far-field imaging mirror, 202-aperture diaphragm, 301-resistor, 302-LED, 401-LED light board, 402-LED lamp beads, 9001-single-chip microcomputer module, 9002-serial port to network module. DETAILED DESCRIPTION

[0052] In order to make the purpose, advantages and features of the present invention clearer, the laser spatial filtering pinhole illumination monitoring system and method based on back-illuminated laser space filtering proposed by the present invention are further described in detail below in conjunction with the accompanying drawings and specific embodiments. It should be understood by those skilled in the art that these implementations are only used to explain the technical principles of the present invention, and are not intended to limit the scope of protection of the present invention.

[0053] like Figure 1 , Figure 2 As shown, the present invention is based on a back-illuminated laser spatial filter pinhole illumination monitoring system, comprising a spatial filter 102, an optical imaging module 103, an electric control system 100, a detector 104, an L1 lens 2001, a filter pinhole 2002, an illumination light source 2003, and an L2 lens 2004; the spatial filter 102 is composed of an L1 lens 2001, an L2 lens 2004, a filter pinhole 2002, and an illumination light source 2003, and the optical imaging module 103 comprises 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 on the outgoing light path of the laser light source 101 to be measured, wherein the laser light source 101, the spatial filter 102, the optical imaging module 103, and the detector 104 remain coaxial in the entire light path.

[0054] In the present invention, a laser light source is used as the laser to be measured, with a wavelength of 351 nm. After passing through the spatial filter 102 and the optical imaging module 103, a far-field focal spot image is formed on the detector 104. The working principle of the above optical system is: the end face of the filter pinhole 2002 is coplanar with the focal planes of the L1 lens 2001 and the L2 lens 2004. The illumination light source 2003 is located behind the filter pinhole 2002, and the cone light emitted by it illuminates the end face of the pinhole. After the scattered light of the end face passes through the L2 lens 2004 and the far-field imaging mirror 201, a pinhole image is formed 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 through-hole deviation can be known. The detector 104 is used to collect the image formed by the filter pinhole 2002 and the strong laser on the photosensitive surface of the detector 104, and provide test data for optical path alignment and focal spot measurement.

[0055] The spatial filter 102 is used in the system to filter out high-frequency stray light. The size of the filter pinhole 2002 is usually calculated according to 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 according to the beam reduction ratio of the spatial filter 102. The focal length and the size of the filter pinhole 2002 jointly determine the size of the cutoff frequency. In order to monitor the through-hole position of the laser at the filter pinhole 2002, it is necessary to image the laser focal spot at the filter pinhole 2002 and the inner circle of the filter pinhole at the same time. The L2 lens 2004 and the far-field imaging mirror 201 constitute a set of imaging systems. 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 pinhole are imaged simultaneously. Assuming that the diameter of the filter pinhole 2002 is d, the focal length of the L2 lens 2004 is f1, and the focal length of the far-field imaging mirror 201 is f2, the inner edge diameter of the pinhole image is d×f2 / f1. The diameter of the light-clearing hole will affect the width of the bright ring of the pinhole image. Selecting a diameter not less than the diameter of the filter pinhole can ensure that the ring width is greater than zero. The imaging quality of the far-field pinhole is improved by reducing the numerical aperture of the imaging beam, so an aperture stop 202 is added after the far-field imaging mirror 201. The position of the aperture stop 202 should be as close as possible to the far-field imaging mirror 201, and its size should be as large as possible on the basis of meeting the image quality requirements.

[0056] The electric control system 100 is used to realize the driving control of the illumination light source 2003, the shift control of the electric translation stage, the acquisition control of the detector 104, and the display and processing functions of the filter pinhole 2002 image. In the present invention, the electric control system 100 includes an illumination control module 1001, a network switch 1002, a motor driver 1003, an illumination drive module 1004, a computer 1005, and an electric translation stage 1006; the illumination drive module 1004 is used to drive the illumination light source 2003 and provide a stable current for the illumination light source. The illumination control module 1004 is used to control the opening and closing of the illumination, adjust the size of the driving current, and then control the brightness of the illumination; the network switch 1002 realizes the network communication between the computer 1005 and the detector 104, the illumination control module 1001 and the motor driver 1003. The computer 105, as a master control device, realizes the control of the detector 104, the illumination control module 1001 and the motor driver 1003. The motor driver 1003 is used to realize the driving control of the electric translation stage 1006 . The electric translation stage 1006 carries the detector 104 and is used to adjust the position of the detector 104 and the filter aperture 2002 to realize the focusing of the detector 104 .

[0057] like Figure 3 , Figure 4 As shown, the lighting source part of the present invention adopts ultraviolet LED, and the hardware circuit adopts a plurality of LEDs in series, and a resistor 301 is connected in parallel to each LED 302. The advantage of the above design is that when an open circuit fault occurs in the LED, the current flows through the resistor connected in parallel with it, and does not affect the operation of other LEDs; when a short circuit fault occurs in the LED, other LEDs can continue to work, and will not cause the overall failure of the lighting source, thereby improving the reliability of the system. The number of LED lamp beads 402 is determined by the brightness and uniformity of the image formed on the detector 104, and the voltage between V+_V- is the sum of the voltage drops on each LED. The LED lamp beads 402 and the resistor 301 are welded on the LED lamp board 401. The LED lamp board 401 adopts an aluminum substrate, and a plurality of LED lamp beads 402 are evenly arranged around a ring belt. In order to make full use of the heat dissipation area without increasing the cost, the shape of the LED lamp board 401 adopts a design scheme of outer square and inner circle.

[0058] 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, the value range of the LED current is: 0-60mA, and the radiation power of a single LED is up to 26mW. The hardware circuit uses 8 LEDs in series, and a 10Kohm resistor is connected in parallel to each LED. The voltage after the 8 LEDs are connected in series is 28V.

[0059] As shown in Figures 6(a), 6(b) and 6(c), the principle of using direct illumination, indirect illumination and back illumination on the LED light board is explained: In order to prevent the LED light board from being damaged by strong laser, the back illumination design is adopted in the example of the present invention. The direct illumination is shown in Figure 6(a): the LED light board 401 is located between the laser light source 101 and the filter aperture 2002, the LED lamp beads 402 are directly opposite the filter aperture 2002, the filter aperture 2002 has a diameter of 10mm, the inner diameter of the LED light board 401 is 12mm, and the LED lamp beads 401 are evenly arranged around a circle with a diameter of 18.6mm. After the LED lighting 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 direct illumination is that the LED light source is easily damaged by the irradiation of the laser light source. The specific analysis is as follows: during the calibration process, the laser may deviate from the center of the aperture and hit the filter aperture plate. After being reflected by the filter aperture plate, it may damage the LED light board.

[0060] The indirect type is shown in Figure 6(b): the LED light board 404 is on the right side of the filter hole 2002, and the LED lamp bead 402 is directly imaged on the detector 104 through the optical system. The position of the center of the hole is indirectly determined based on the position of the LED lamp bead 402. The disadvantages of the indirect type are: 1) the center position of the hole cannot be accurately determined; 2) it is easily damaged by the reflected laser and the lighting function fails.

[0061] Because both of the above two methods have some defects, in the embodiment of the present invention, the back-illumination method is adopted, as shown in FIG6(c): the LED light board 401 is on the right side of the filter aperture 2002, the LED lamp beads 402 are facing away from the optical system, the aperture diameter is 10 mm, the inner diameter of the LED light board 401 is 12 mm, and the LED lamp beads 402 are evenly arranged in a circle with a diameter of 18.6 mm. After the LED lighting 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-illumination method is that it can prevent the illumination light source from 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.

[0062] like Figure 5As shown, in the example of the present invention, the hardware circuit of the lighting driver module 1004 uses TI's TPS61161A as the LED constant current driver chip. The circuit works in boost mode with an operating frequency of 600KHz, which can further reduce the output ripple, improve the efficiency of the converter, and allow the use of fewer external components. The circuit has an open circuit protection function and reserves an external interface for current regulation. The output current can be controlled by inputting a PWM signal. The external interface of the circuit includes: VI+, VI-, Vo+, Vo-, DIM. The input ports are VI+, VI-, DIM, and the output ports are Vo+, 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 light source 2003, and the output pin Vo- of the lighting driver module 1004 is connected to the V- of the lighting light source 2003.

[0063] like Figure 7 As shown, the lighting control module 1001 is composed of a single-chip microcomputer module 9001 and a serial port to network module 9002. The single-chip microcomputer module 9001 is composed of a single-chip microcomputer and peripheral circuits, and is used to realize lighting control of the lighting driving module 1004. The serial port to network module 9002 is used to convert the serial port communication protocol into the network communication protocol, and realize the control of the lighting light source 2003 by the computer 105. The interface between the serial port to network module 9002 and the single-chip microcomputer module 9001 is a serial port.

[0064] like Figure 8 — Fig. 9 As shown, the present invention also provides a monitoring method based on a back-illuminated laser spatial filtering pinhole illumination monitoring system, comprising the following steps:

[0065] 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 driving module 1004 to work;

[0066] Step 2, the lighting driving module 1004 provides a driving current to the lighting light source 2003, and the lighting light source 2003 emits light and illuminates the filter aperture 2002;

[0067] Step 3, the filter aperture 2002 is imaged on the detector 104 through the optical imaging module 103, and the detector 104 collects the image on the photosensitive surface of the detector in the continuous working mode and displays it through the computer 1005;

[0068] Step 4, according to the clarity of the image of the filter pinhole 2002 on the detector 104, the distance between the detector 104 and the optical imaging module 103 is adjusted by the electric translation stage 1006 to obtain a clear image of the edge of the pinhole;

[0069] Step 5, the laser light source 101 to be tested emits laser light, and after the laser light passes through the spatial filter 102 and the optical imaging module 103, it is imaged on the photosensitive surface of the detector 104 to form a far-field focal spot;

[0070] Step 6, the detector 104 collects the filter pinhole 2002 and the far-field focal spot image, adjusts the emission angle of the laser light source 101 to be tested according to the relative position of the filter pinhole 2002 and the far-field focal spot, realizes the collimation of the light path, and transmits the far-field focal spot image data formed by the laser light source 101 to be tested on the detector 104 after the light path is collimated to the computer 1005 through the network switch 1002, thereby completing the laser spatial filter pinhole illumination monitoring based on back illumination.

[0071] The specific steps of the single chip microcomputer module 9001 in step 1 are:

[0072] Step 1.1, the microcontroller is powered on and initialized and waits for receiving instructions from the computer 1005;

[0073] Step 1.2, the single chip microcomputer receives the instruction sent by the computer 1005 and makes a judgment;

[0074] Step 1.3: According to the judgment results, perform the following controls respectively:

[0075] If it is determined to be a lighting on instruction, the corresponding IO port is set to 1 and a response signal is sent to the computer 1005;

[0076] If it is determined to be a lighting off instruction, the corresponding IO port is set to 0 and a response signal is sent to the computer 1005;

[0077] It is determined to be a query status instruction, and the query value of each IO port internal register is started, and the query value is provided to the computer 1005;

[0078] It is determined to be a PWM dimming instruction, the PWM dimming program is started, the corresponding IO port generates a PWM signal, the PWM dimming of the lighting source is realized, and a response signal is generated to the computer 1005.

[0079] Step 1.4, complete the instruction, and the program returns to the state of waiting to receive instructions.

[0080] As shown in FIG10(a), it is an imaging effect diagram obtained by indirect illumination, and FIG10(b) is an imaging effect diagram obtained by back-illuminated illumination (without aperture stop). From the comparison of the two figures, it can be seen that since indirect illumination relies on the position of the lamp bead to indirectly determine the position of the center of the small hole, its positioning accuracy is slightly lower than that of back-illuminated illumination. FIG10(c) is an imaging effect diagram obtained by back-illuminated illumination (adding an aperture stop with a diameter of 10 mm), in which the inner diameter of the bright ring corresponds to the filter small hole 2002, and the outer diameter of the bright ring corresponds to the inner diameter of the illumination light source LED lamp board 401. Theoretically, the inner diameter of the bright ring should be 3.29 mm, and the outer diameter of the bright ring should be 3.95 mm. By adjusting the relative position of the aperture stop 202 and the detector 104, the inner diameter of the bright ring is obtained to be between 3.03 and 3.35 mm, and the outer diameter of the bright ring is between 3.9 mm and 4.05 mm, so that a value closer to the theory can be obtained. In the case where the aperture stop 202 is not added, more stray light enters, so the inner diameter of the bright ring will be smaller and the edge will not be clear enough.

[0081] like Fig.11 As shown in the figure, under the indirect lighting mode, two LED lamp beads in the lighting source are damaged by laser. This figure illustrates two points: 1) In the indirect lighting mode, the problem of the lighting source being damaged by the high-power laser does exist, while in the back-illuminated mode, since the lighting source is not in the high-power laser light path, the risk of being damaged by the high-power laser is avoided to the greatest extent, ensuring the stable and reliable operation of the lighting source; 2) Since the lighting source adopts the method of connecting each LED lamp bead in series + connecting resistors in parallel, in the event of an open circuit failure of a single LED, other LEDs can still work normally, and will not cause the overall failure of the lighting source. This is also a feature of the lighting source.

[0082] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention 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 replace some or all of the technical features therein with equivalents. However, these modifications or replacements 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 filtering pinhole illumination monitoring system, characterized in that: The device comprises a spatial filter (102), an optical imaging module (103), an electric control system (100) and a detector (104); the spatial filter (102), the optical imaging module (103) and the detector (104) are sequentially arranged on an outgoing light path of a laser light source (101) to be measured, and the electric control system (100) controls the spatial filter (102) and the detector (104) respectively; The electric control system (100) comprises 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 respectively connected to the detector (104), the lighting control module (1001) and the electric driver (1003); the lighting control module (1001) is connected to the lighting drive module (1004) for controlling the on and off of the lighting; the motor driver (1003) is connected to the electric translation stage (1006) for driving and controlling the electric translation stage (1006); the computer (1005) is connected to the network switch (1002) for respectively controlling the detector (104), the lighting control module (1001) and the motor driver (1003) through the network switch (1002); The spatial filter (102) comprises a filter pinhole (2002) and an illumination light source (2003) which are sequentially arranged along an optical path; the illumination light source (2003) is back-illuminated; the illumination drive module (1004) is connected to the illumination light 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 pinhole (2002) in the spatial filter (102) to achieve focusing of the detector (104).

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

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

4. The back-illuminated laser spatial filtering pinhole illumination monitoring system according to claim 1, 2 or 3, characterized in that: The lighting control module (1001) comprises a single-chip microcomputer module (9001) and a serial port to network module (9002); the single-chip microcomputer module (9001) is composed of a single-chip microcomputer and peripheral circuits to realize control of the lighting drive module (1004), and the serial port to network module (9002) is connected to the single-chip microcomputer module (9001) via a serial port; the serial port to network module (9002) is connected to a network switch (1002) to convert a serial port communication protocol into a network communication protocol, thereby realizing control of the lighting light source (2003) by a computer (1005).

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

6. The back-illuminated laser spatial filtering pinhole illumination monitoring system according to claim 5 is characterized in that: The lighting light source (2003) is an ultraviolet LED, comprising an LED lamp bead (402) and an LED lamp board (401); the resistor (301) is welded on the LED lamp board (401); the LED lamp board (401) adopts an aluminum substrate, a light-through hole is provided in the middle thereof, and a plurality of LED lamp beads (402) are evenly arranged on the LED lamp board (401) along the circumference around the light-through hole.

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

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

9. A back-illuminated laser spatial filter pinhole illumination monitoring method, using the back-illuminated laser spatial filter pinhole illumination monitoring system according to any one of claims 1 to 8, characterized in that: The following steps are involved: 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 driving module (1004) to work; Step 2: the lighting driving module (1004) provides a driving current to the lighting light source (2003), and the lighting light 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), and the detector (104) collects the image on the photosensitive surface of the detector in a continuous working mode and displays it through the computer (1005); Step 4, according to the clarity of the image of the filter pinhole (2002) on the detector (104), the distance between the detector (104) and the optical imaging module (103) is adjusted by the electric translation stage (1006) to obtain an image with a clear edge of the pinhole; Step 5, the laser light source to be tested (101) emits laser light, and after the laser light passes through the spatial filter (102) and the optical imaging module (103), it forms an image on the photosensitive surface of the detector (104) to form a far-field focal spot; Step 6, the detector (104) collects the filter pinhole (2002) and the far-field focal spot image, adjusts the emission angle of the laser light source (101) to be measured according to the relative position of the filter pinhole (2002) and the far-field focal spot, realizes the collimation of the light path, and transmits the far-field focal spot image data formed on the detector (104) by the laser light source (101) to the computer (1005) through the network switch (1002), thereby completing the back-illuminated laser spatial filter pinhole illumination monitoring.

10. The back-illuminated laser spatial filtering pinhole illumination monitoring method according to claim 9, characterized in that: In step 1, the lighting control module (1001) receives instructions through the single-chip computer module (9001) and controls the lighting driving module (1004) to work; the specific steps of the single-chip computer module (9001) to perform control are: Step 1.1, the microcontroller is powered on and initialized and waits for receiving instructions from the computer (1005); Step 1.2, the single chip microcomputer receives the instruction sent by the computer (1005) and makes a judgment; Step 1.3: According to the judgment results, perform the following controls respectively: Determining that it is a lighting-on instruction, setting the corresponding IO port to 1, and sending a response signal to the computer (1005); Determining that it is a lighting off instruction, setting the corresponding IO port to 0, and sending a response signal to the computer (1005); It is determined to be a query status instruction, and the query of the value of the internal register of each IO port is started, and the query value is provided to the computer (1005); Determining that it is a PWM dimming instruction, starting the PWM dimming program, the corresponding IO port generates a PWM signal, realizes 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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