Laser ablation threshold test device and test method based on Raman spectroscopy

Abstract

This invention relates to a laser ablation threshold testing device and method based on Raman spectroscopy, comprising a laser emitting unit, a beam splitting unit, a beam expander unit, a laser testing unit, an automatic displacement testing unit, a Raman spectral signal separation and acquisition unit, a spectrometer unit, and a computer control unit. The laser emitting unit outputs a pulsed laser beam. The beam splitting unit, beam expander unit, and laser testing unit are arranged sequentially along the optical path of the pulsed laser beam. The automatic displacement testing unit is located at the focal position of the beam expander unit. The Raman spectral signal separation and acquisition unit and the spectrometer unit are arranged sequentially along the transmission direction of the beam splitting unit. The computer control unit is electrically connected to the spectrometer unit. This invention enables laser ablation threshold testing of irregular mineral samples and provides a testing method combining microscopic images and Raman spectroscopy, making the ablation threshold test more accurate and improving the automation and efficiency of the test.

Description

Technical Field

[0001] This invention belongs to the field of laser measurement technology, and particularly relates to a laser ablation threshold testing device and method based on Raman spectroscopy. Background Technology

[0002] As an active spectroscopy technique, the signal quality of Raman spectrometers is closely related to the laser energy. If the laser energy density is too high, laser ablation can occur, leading to melting, vaporization, amorphization, or sputtering of the sample, altering its physicochemical properties and affecting Raman spectroscopy detection. Without ablation, the laser power density on the sample surface is positively correlated with the intensity of the excited Raman signal. Therefore, to ensure that the Raman spectrometer acquires the highest possible Raman signal without causing sample ablation, it is necessary to characterize the laser ablation threshold of common minerals and some organic compounds in the laboratory to guide the laser energy setting.

[0003] Currently, research on laser ablation threshold mainly focuses on laser optical components or crystal materials, with fewer methods available for testing the laser ablation threshold of mineral samples. Threshold testing for general optical components typically utilizes a specific laser ablation threshold testing platform. This platform uses a lens to focus the laser beam, employs a displacement platform to perform point-by-point damage testing, and then examines the irradiated points for ablation using images or visual inspection. Existing laser ablation threshold testing platforms require redundant experimental components, occupy excessive experimental space, and are expensive. Furthermore, they are generally only suitable for testing regularly shaped optical components or crystal materials, requiring significant manpower and time, especially when measuring large components or multi-pulse laser damage thresholds. Summary of the Invention

[0004] The purpose of this invention is to solve one of the above-mentioned technical problems by providing a laser ablation threshold testing device and method based on Raman spectroscopy, which characterizes the laser ablation threshold of irregularly shaped mineral samples by acquiring microscopic images and Raman spectra.

[0005] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0006] A laser ablation threshold testing device based on Raman spectroscopy, comprising:

[0007] Laser emitting unit: used to output pulsed laser beams and adjust the power of the output laser;

[0008] Automatic displacement testing unit: used to place the sample to be tested and to make the sample move in three dimensions;

[0009] Beam separation unit: Located in the emission direction of the pulsed laser beam, it is used to reflect the pulsed laser beam and transmit the Raman scattered light excited by the pulsed laser beam on the surface of the sample under test;

[0010] Beam expander unit: Located along the optical path of the pulsed laser beam in the reflection direction of the beam splitter unit, used to change the beam diameter of the pulsed laser beam and to collect and transmit the Raman scattered light excited by the pulsed laser beam on the surface of the sample under test; Automatic displacement testing unit is located at the focal position of the beam expander unit along the optical path of the pulsed laser beam.

[0011] Laser testing unit: A movable unit located between the beam expander unit and the automatic displacement testing unit, used to measure the laser power on the surface of the sample under test and the shape and diameter of the laser spot on the surface of the sample under test;

[0012] Raman spectroscopy signal separation and acquisition unit: The optical path of the Raman scattered light collected by the beam expander unit is set in the transmission direction of the beam separation unit to eliminate Rayleigh scattered light excited by the pulsed laser beam on the surface of the sample to be tested;

[0013] Spectrometer unit: The optical path of the Raman scattered light collected by the beam expander unit is set at the focal position of the Raman spectral signal separation and acquisition unit to receive the Raman scattered light and convert the Raman scattered light signal into a Raman scattered electrical signal;

[0014] Computer control unit: electrically connected to the laser emitting unit, used to adjust the laser emission parameters of the laser emitting unit; electrically connected to the automatic displacement testing platform, used to adjust the position of the sample to be tested on the automatic displacement testing platform; electrically connected to the spectrometer unit, used to adjust the spectral acquisition parameters of the spectrometer unit, and used to acquire the Raman scattering electrical signal output by the spectrometer unit, and draw Raman spectra based on the Raman scattering electrical signal.

[0015] In some embodiments of the present invention, the invention further includes:

[0016] Microscopic imaging unit: Located between the beam splitting unit and the beam expander unit, it is used to acquire surface image information of the sample to be tested; the microscopic imaging unit includes a microscopic imaging camera, a long-pass filter and a first flip mounting base, the long-pass filter is mounted on the first flip mounting base, and the first flip mounting base is used to rotate the long-pass filter to move it into or out of the optical path of the pulsed laser beam;

[0017] The computer control unit is electrically connected to the microscopic imaging unit and is used to adjust the microscopic imaging parameters of the microscopic imaging unit. It is also used to acquire surface image information of the sample under test collected by the microscopic imaging unit and to determine the ablation status of the sample under test based on the surface image information.

[0018] In some embodiments of the present invention, the laser emitting unit includes a pulsed laser, a laser attenuator, a first total reflection mirror, and a second total reflection mirror. The laser attenuator is disposed at the output port of the pulsed laser and is used to change the pulse energy of the pulsed laser beam. The first total reflection mirror is disposed in the output optical path of the laser attenuator, and the second total reflection mirror is disposed in the reflected optical path of the first total reflection mirror. Both the first and second total reflection mirrors are used to change the direction of the pulsed laser beam.

[0019] In some embodiments of the present invention, the beam expander unit includes a zoom lens, a fixed lens, and a compensation lens arranged sequentially along the optical path direction of the pulsed laser beam. By changing the relative positions of the zoom lens, the fixed lens, and the compensation lens, the magnification and focal length of the beam expander unit can be adjusted.

[0020] In some embodiments of the present invention, the laser testing unit includes a beam quality analyzer, a third total reflection mirror, and a second flip mounting base. The third total reflection mirror is mounted on the second flip mounting base, which is used to rotate the third total reflection mirror to move it into or out of the optical path of the pulsed laser beam. The third total reflection mirror is used to reflect the pulsed laser beam into the beam quality analyzer. The beam quality analyzer is disposed on the reflected optical path of the third total reflection mirror and is used to measure the laser power on the surface of the sample under test and the shape and diameter of the laser spot on the surface of the sample under test.

[0021] In some embodiments of the present invention, the Raman spectroscopy signal separation and acquisition unit includes a collecting lens and a high-pass filter arranged sequentially along the optical path of the Raman scattered light collected by the beam expander unit. The collecting lens is used to couple the Raman scattered light into the spectrometer unit, and the high-pass filter is used to eliminate Rayleigh scattered light excited by the pulsed laser beam on the surface of the sample to be tested.

[0022] Some embodiments of the present invention further provide a laser ablation threshold testing method based on Raman spectroscopy, comprising the following steps:

[0023] S1: Determine the ablation test origin on the surface of the sample to be tested, and set the test grid based on the ablation reference origin;

[0024] S2: Acquire the initial microscopic image of each test point in the test grid and the initial Raman signal of each test point;

[0025] S3: Select a test point, irradiate the test point with a pulsed laser beam, adjust and record the laser power and spot shape of the sample surface at the test point, take a microscopic image of the sample surface at the test point and obtain the Raman spectrum of the sample surface at the test point, determine the damage of the sample based on the microscopic image and Raman spectrum, and record the laser power, spot diameter and damage state of the sample surface when damage occurs.

[0026] S4: Adjust the position of the sample to be tested, change the test point, and repeat step S3 until the measurement of all test points in the test grid is completed. Based on the laser power, spot diameter and damage state of the sample to be tested measured at each test point, the laser ablation threshold of the sample to be tested is obtained.

[0027] In some embodiments of the present invention, the following steps are included before performing step S1:

[0028] Inspect the laser ablation threshold testing device and adjust it to normal working condition;

[0029] Raman spectra of single-crystal silicon wafers were collected to verify the performance of the Raman spectrometer.

[0030] In some embodiments of the present invention, the method for performing step S1 includes:

[0031] Adjust the laser attenuator and beam expander unit to maximize the laser energy density, ablate the sample to be tested, and generate observable ablation pits on the surface of the sample. Record the location of the ablation pits and use this location as the origin of the ablation test.

[0032] Multiple test points are set up based on the ablation test origin, and the multiple test points are arranged horizontally and vertically to form a test grid.

[0033] In some embodiments of the present invention, the method for performing step S3 includes:

[0034] Adjust the laser attenuator and beam expander units to gradually increase the laser power on the surface of the sample under test and decrease the diameter of the light spot on the surface of the sample under test. During the adjustment process, use a beam quality analyzer to measure and record the laser power value on the surface of the sample under test, as well as the shape and diameter of the light spot on the surface of the sample under test.

[0035] The beneficial effects of this invention are as follows:

[0036] 1. The laser ablation threshold testing device based on Raman spectroscopy provided by this invention is capable of testing the laser ablation threshold of irregular mineral samples.

[0037] 2. The laser ablation threshold testing device based on Raman spectroscopy provided by this invention is equipped with a Raman spectral signal separation and acquisition unit and a spectrometer unit, which can collect and convert Raman scattered light and determine the ablation status of the test point by means of Raman spectroscopy, making the test of the ablation threshold more accurate.

[0038] 3. The laser ablation threshold testing device based on Raman spectroscopy provided by the present invention is also equipped with a microscopic imaging unit, which can acquire microscopic images of the test points. Compared with the previous method of judging the ablation condition by visual inspection, the test of the ablation threshold is more accurate.

[0039] 4. The laser ablation threshold testing device based on Raman spectroscopy provided by this invention automatically adjusts the position of the sample to be tested through an automatic displacement platform, which improves the automation level of the testing device and the efficiency of laser ablation threshold testing.

[0040] 5. The laser ablation threshold testing device based on Raman spectroscopy provided by this invention reduces the size of the testing device and simplifies the testing platform by using optical paths. It also has lower requirements for the operating environment and transportation conditions. It serves the development of Raman spectroscopy payloads, in-situ spectral testing of planetary samples, exploration of planetary life traces, and calibration experiments of planetary payloads, and has a wide range of applications. Attached Figure Description

[0041] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0042] Figure 1 This is a schematic diagram of the laser ablation threshold testing device.

[0043] Figure 2 This is a schematic diagram of the structure of each unit in the laser ablation threshold testing device;

[0044] Figure 3 The flowchart shows the laser ablation threshold testing method based on Raman spectroscopy.

[0045] The attached figures are labeled as follows:

[0046] 100. Laser emitting unit; 101. Pulsed laser; 102. Laser attenuator; 103. First total reflection mirror; 104. Second total reflection mirror;

[0047] 200. Beam separation unit;

[0048] 300. Microscopic imaging unit; 301. Long-pass filter; 302. Microscopic imaging camera;

[0049] 400. Beam expander unit; 401. Zoom lens; 402. Fixed lens; 403. Compensating lens;

[0050] 500. Laser testing unit; 501. Third total reflection mirror; 502. Beam quality analyzer;

[0051] 600. Automatic displacement testing unit;

[0052] 700. Raman spectroscopy signal separation and acquisition unit; 701. High-pass filter; 702. Collection lens;

[0053] 800. Spectrometer Unit;

[0054] 900. Computer control unit. Detailed Implementation

[0055] To make the objectives, technical solutions, and advantages of this application clearer, the application is described and illustrated below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the scope of this application. All other embodiments obtained by those skilled in the art based on the embodiments provided in this application without inventive effort are within the scope of protection of this application.

[0056] It should be noted that the terminology used herein is for the purpose of describing particular implementations only and is not intended to limit the exemplary implementations according to this application. As used herein, unless the context clearly indicates otherwise, the singular form is also intended to include the plural form. Furthermore, it should be understood that the terms “comprising” and “having”, and any variations thereof, are intended to cover non-exclusive inclusion, for example, a process, method, system, product, or apparatus that comprises a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to such process, method, product, or apparatus.

[0057] Where there is no conflict, the embodiments and features in the embodiments of the present invention can be combined with each other.

[0058] The technical solution of the present invention will be described in detail below with reference to specific embodiments and accompanying drawings.

[0059] As attached Figure 1-2 As shown, in an illustrative embodiment of a laser ablation threshold testing device based on Raman spectroscopy according to the present invention, the testing device includes a laser emission unit 100, an automatic displacement testing unit 600, a beam expander unit 400, a laser testing unit 500, a Raman spectral signal separation and acquisition unit 700, a spectrometer unit 800, and a computer control unit 900.

[0060] The laser emitting unit 100 is used to output a pulsed laser beam and adjust the power of the output laser. In this embodiment, the pulsed laser beam is a Gaussian beam with a wavelength of 532nm.

[0061] The automatic displacement testing unit 600 is used to place the sample to be tested and enables the sample to move in three dimensions. The 532nm wavelength pulsed laser beam output by the laser emitting unit 100 passes through the beam splitting unit 200, the beam expander unit 400 and the laser testing unit 500 in sequence and then converges on the surface of the sample to be tested to form a light spot. Rayleigh scattering light with a wavelength similar to that of the pulsed laser beam and Raman scattering light with wavenumber shift are excited within the light spot.

[0062] The beam separation unit 200 is positioned in the emission direction of the pulsed laser beam to reflect the pulsed laser beam and transmit the Rayleigh and Raman scattered light excited by the pulsed laser beam on the surface of the sample under test.

[0063] The beam expander unit 400 is positioned along the optical path of the pulsed laser beam in the reflection direction of the beam splitter unit 200. It is used to change the beam diameter of the pulsed laser beam and to collect and transmit the Rayleigh and Raman scattered light excited by the pulsed laser beam on the surface of the sample to be tested.

[0064] The laser testing unit 500 is movable between the beam expander unit 400 and the automatic displacement testing unit 600, and is used to test the laser power on the surface of the sample to be tested.

[0065] The Raman spectroscopy signal separation and acquisition unit 700 is set along the optical path of the Raman scattered light collected by the beam expander unit 400 in the transmission direction of the beam separation unit 200, in order to eliminate Rayleigh scattered light excited by the pulsed laser beam on the surface of the sample to be tested.

[0066] The spectrometer unit 800 is positioned at the focal point of the Raman spectral signal separation and acquisition unit 700 along the optical path of the Raman scattered light collected by the beam expander unit 400. It is used to receive the Raman scattered light and convert the Raman scattered light signal into a Raman scattered electrical signal.

[0067] The computer control unit 900 is connected to the laser emission unit 100, the automatic displacement testing platform 600, and the spectrometer unit 800 via data cables. The computer control unit 900 includes a laser adjustment module, an automatic displacement testing platform control module, and a Raman spectrum plotting module. The laser adjustment module is used to adjust the laser emission parameters of the laser emission unit 100, the automatic displacement testing platform control module is used to adjust the position of the sample to be tested on the automatic displacement testing unit 600, and the Raman spectrum plotting module is used to adjust the spectral acquisition parameters of the spectrometer unit 800, such as integration time, number of accumulations, and gain factor, and to acquire the Raman scattering electrical signal output by the spectrometer unit 800 and plot the Raman spectrum based on the Raman scattering electrical signal.

[0068] It should be noted that the pulsed laser 101 used in the laser emitting unit 100 of the present invention is a green laser with a wavelength of 532nm. However, by selecting a suitable laser emitting unit 100, beam separation unit 200 and Raman spectral signal separation and acquisition unit 700, the principle of the present invention can also be applied to situations using lasers of other wavelengths.

[0069] In some embodiments of the present invention, the laser ablation threshold testing device further includes a microscopic imaging unit 300, which is disposed between the beam separation unit 200 and the beam expander unit 400, and is used to acquire surface image information of the sample to be tested, so as to more accurately determine the ablation status of the sample surface.

[0070] The microscopic imaging unit 300 includes a microscopic imaging camera 302, a long-pass filter 301, and a first flip mounting base. The long-pass filter 301 is mounted on the first flip mounting base, which is used to rotate the long-pass filter 301 by 90 degrees to move it into or out of the optical path of the pulsed laser beam. The operating spectral band of the microscopic imaging camera 302 is 460nm-540nm.

[0071] The computer control unit 900 is connected to the microscope imaging camera 302 via a data cable. The computer control unit 900 further includes a microscope image drawing module, which is used to adjust the microscope imaging parameters of the microscope imaging camera 302, such as the exposure time, and to acquire surface image information of the sample under test collected by the microscope imaging camera 302, and to determine the ablation status of the sample under test based on the surface image information.

[0072] In some embodiments of the present invention, the laser emitting unit 100 includes a pulsed laser 101, a laser attenuator 102, a first total reflection mirror 103, and a second total reflection mirror 104. The laser attenuator 102 is disposed at the output port of the pulsed laser 101 and is used to change the pulse energy of the pulsed laser beam. The first total reflection mirror 103 is disposed in the output optical path of the laser attenuator 102, and the second total reflection mirror 104 is disposed in the reflected optical path of the first total reflection mirror 103. Both the first total reflection mirror 103 and the second total reflection mirror 104 are used to change the direction of the pulsed laser beam.

[0073] In some embodiments of the present invention, the automatic displacement testing platform 600 includes a self-centering optical gripper, a scissor lift platform, and two stepper motors. The self-centering optical gripper is used to fix the sample to be tested, the two stepper motors are used to control the self-centering optical gripper to move horizontally in the x-axis and y-axis directions, respectively, and the scissor lift platform is used to adjust the relative height of the automatic displacement testing platform 600 in the z-axis direction.

[0074] In some embodiments of the present invention, the beam separation unit 200 includes a 532nm dichroic filter for reflecting the 532nm pulsed laser beam output by the laser emitting unit 100 at a 45° angle, and can transmit Raman scattered light of 535nm-780nm.

[0075] In some embodiments of the present invention, the beam expander unit 400 includes a zoom lens 401, a fixed lens 402, and a compensation lens 403 arranged sequentially along the optical path direction of the pulsed laser beam, which respectively serve to zoom, fix, and compensate. By changing the relative positions of the zoom lens 401, the fixed lens 402, and the compensation lens 403, the magnification and focal length of the beam expander unit 400 can be adjusted.

[0076] In some embodiments of the present invention, the laser testing unit 500 includes a beam quality analyzer 502, a third total reflection mirror 501, and a second flip mounting base. The third total reflection mirror 501 is mounted on the second flip mounting base, which is used to rotate the third total reflection mirror 501 to move it into or out of the optical path of the pulsed laser beam. The third total reflection mirror 501 is used to reflect the pulsed laser beam into the beam quality analyzer 502. The beam quality analyzer 502 is disposed on the reflected optical path of the third total reflection mirror 501 and is used to measure the laser power on the surface of the sample under test and the shape and diameter of the laser spot on the surface of the sample under test.

[0077] In some embodiments of the present invention, the Raman spectroscopy signal separation and acquisition unit 700 includes a collection lens 702 and a high-pass filter 701 arranged sequentially along the optical path of the Raman scattered light collected by the beam expander unit 400. The collection lens 702 is used to couple the Raman scattered light into the spectrometer unit 800, and the high-pass filter 701 is used to eliminate Rayleigh scattered light excited by the pulsed laser beam on the surface of the sample to be tested.

[0078] The specific working process of the laser ablation threshold testing device based on Raman spectroscopy provided by the present invention is as follows: In use, the pulsed laser 101 of the laser emitting unit 100 is turned on, and the pulsed laser 101 outputs a 532nm wavelength pulsed laser beam. When the pulsed laser beam is emitted, it passes through the laser attenuator 102 placed at the output port of the pulsed laser 101, and is reflected by the first total reflection mirror 103 and the second total reflection mirror 104 in sequence to change the direction of the optical path. After being reflected by the second total reflection mirror 104, the pulsed laser beam is incident on the beam separation unit 200 at 45° and is reflected by the beam separation unit 200. After being reflected by the beam separation unit 200, the laser pulse beam passes through the beam expander unit 400 and the laser testing unit 500 in sequence, and finally converges on the surface of the sample to be tested on the automatic displacement testing unit 600, and forms a light spot on the surface of the sample to be tested. Rayleigh scattering light with a wavelength similar to that of the pulsed laser beam and Raman scattering light with wavenumber shift are excited within the light spot range. When the pulsed laser beam passes through the laser testing unit 500, it is reflected by the third total reflection mirror 501 and enters the beam quality analyzer 502 to measure the laser power on the surface of the sample and the shape and diameter of the light spot on the surface of the sample.

[0079] The Rayleigh and Raman scattered light generated by the excitation passes in opposite directions through the third total reflection mirror 501 and the beam expander unit 400, and is collected by the beam expander unit 400 to form a collimated beam. After exiting the beam expander unit 400, the collimated beam passes sequentially through the microscopic imaging unit 300 and the beam separation unit 200 into the Raman spectral signal separation and acquisition unit 700. When the collimated beam passes through the microscopic imaging unit 300, it is reflected by the long-pass filter 301 and enters the microscopic imaging camera 302 to form a microscopic image. The collimated beam in the Raman spectrum... The Rayleigh scattering light in the signal separation and acquisition unit 700 is eliminated by a 532nm high-pass filter 701 and coupled into the spectrometer unit 800 by the collecting lens 702. The spectrometer unit 800 converts the Raman scattering light signal into a Raman scattering electrical signal and transmits the Raman scattering electrical signal to the computer control unit 900. The computer control unit 900 plots the Raman spectrum based on the Raman scattering electrical signal and processes the Raman spectrum, transforming the horizontal axis or subtracting the dark current to make it a Raman spectrum that can be easily analyzed.

[0080] This invention also provides a laser ablation threshold testing method based on Raman spectroscopy, as shown in the attached figure. Figure 3 As shown, it includes the following steps.

[0081] S1: Determine the ablation test origin on the surface of the sample to be tested, and set the test grid based on the ablation reference origin;

[0082] In some embodiments of the present invention, before performing step S1, the following steps are also included: testing the laser ablation threshold testing device and adjusting it to normal working condition; acquiring the Raman spectrum of a single-crystal silicon wafer to verify the performance of the Raman spectrometer.

[0083] In some embodiments of the present invention, the execution method of step S1 includes: adjusting the laser attenuator 102 and the beam expander unit 400 to adjust the laser energy density to the maximum, ablating the sample to be tested, generating observable ablation pits on the surface of the sample to be tested, recording the location of the ablation pits, and using the location as the origin of the ablation test.

[0084] Multiple test points are set based on the ablation test origin. The multiple test points are arranged horizontally and vertically to form a test grid. The spacing between adjacent test points in the test grid can be selected as needed. In this embodiment, it is 3mm.

[0085] S2: Acquire the initial microscopic image of each test point in the test grid and the initial Raman signal of each test point;

[0086] S3: Select a test point, irradiate the test point with a pulsed laser beam, adjust and record the laser power and spot shape of the sample surface at the test point, take a microscopic image of the sample surface at the test point and obtain the Raman spectrum of the sample surface at the test point, determine the damage of the sample based on the microscopic image and Raman spectrum, and record the laser power, spot diameter and damage state of the sample surface when damage occurs.

[0087] In some embodiments of the present invention, the method for adjusting and recording the laser power and spot shape of the sample surface at the test point includes: adjusting the laser attenuator 102 and the beam expander unit 400, gradually increasing the laser power of the sample surface, decreasing the spot diameter of the sample surface, and using a beam quality analyzer 502 to measure and record the laser power value of the sample surface and the shape and diameter of the spot on the sample surface during the adjustment process.

[0088] The following describes the specific implementation effects of the laser ablation threshold testing method based on Raman spectroscopy provided by this invention, using a laser ablation threshold testing device as an example.

[0089] First, the laser ablation threshold testing device was tested and adjusted to normal working condition. The single-crystal silicon wafer was fixed on the automatic displacement testing unit 600, the beam expander unit 400 was adjusted to the maximum magnification, and the laser attenuator 102 was adjusted to the position with the minimum attenuation. The Raman spectrum signal of the single-crystal silicon wafer was collected to verify the performance of the Raman spectrometer.

[0090] After acquiring the Raman spectrum signal of the single-crystal silicon wafer, the wafer is removed, the sample is fixed, and the attenuation factor of the laser attenuator 102 and the position of the zoom lens 401 in the beam expander unit 400 are adjusted to maximize the laser energy density. The sample is then ablated, creating observable ablation pits on its surface. These pits are recorded as the origin of the ablation test for microscopic imaging and subsequent ablation experiments. Multiple test points are established based on this origin, and each test point is assigned a unique number. For example, 10 test points can be defined as test point 1 to test point 10. These test points are arranged horizontally and vertically to form a test grid, with a 3mm spacing between adjacent test points within the grid.

[0091] After setting the test grid, the microscopic imaging camera 302 is started to sequentially capture the initial microscopic images of each test point along the test grid; the spectrometer unit 800 is started to sequentially acquire the initial Raman spectral signals of each test point along the test grid.

[0092] After acquiring the initial microscopic image and initial Raman spectral signal, the automatic displacement testing unit 600 is adjusted to bring the sample to test point 1. The laser attenuator 102 and beam expander unit 400 are gradually adjusted to increase the laser power on the sample surface and decrease the spot diameter. Simultaneously, the laser testing unit 500 measures and records the laser power value, as well as the shape and diameter of the spot. During the adjustment process, the microscopic imaging unit 300 captures a microscopic image of test point 1, and the spectrometer unit 800 and computer control unit 900 work together to acquire the Raman spectrum of test point 1 to determine the damage status of the sample. Once damage is observed, irradiation of test point 1 is stopped, and the laser power, spot diameter, and damage state of the sample at the time of damage are recorded.

[0093] After completing the ablation test of test point 1, adjust the automatic displacement test unit 600, change the test point, and repeat the above test steps for test point 1 until the ablation test of all test points in the test grid is completed.

[0094] Based on the laser power, spot diameter, and damage status of the sample measured at each test point, the laser ablation threshold of the sample is obtained through analysis.

[0095] Finally, it should be noted that the various embodiments in this specification are described in a progressive manner, with each embodiment focusing on the differences from other embodiments. The same or similar parts between the various embodiments can be referred to each other.

[0096] The above embodiments are only used to illustrate the technical solutions of the present invention and not to limit them; although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications can still be made to the specific implementation of the present invention or equivalent substitutions can be made to some technical features without departing from the spirit of the technical solutions of the present invention, and all such modifications and substitutions should be covered within the scope of the technical solutions claimed in the present invention.

Claims

1. A laser ablation threshold testing device based on Raman spectroscopy, characterized in that, include: Laser emitting unit: used to output pulsed laser beams and adjust the power of the output laser; Automatic displacement testing unit: used to place the sample to be tested and to make the sample move in three dimensions; Beam separation unit: disposed in the emission direction of the pulsed laser beam, used to reflect the pulsed laser beam and transmit the Raman scattered light excited by the pulsed laser beam on the surface of the sample to be tested; Beam expander unit: disposed along the optical path of the pulsed laser beam in the reflection direction of the beam separation unit, used to change the beam diameter of the pulsed laser beam, and to collect and transmit the Raman scattered light excited by the pulsed laser beam on the surface of the sample under test; the automatic displacement testing unit is disposed along the optical path of the pulsed laser beam at the focal position of the beam expander unit. Laser testing unit: It is movable between the beam expander unit and the automatic displacement testing unit, and is used to measure the laser power on the surface of the sample under test and the shape and diameter of the laser spot on the surface of the sample under test; The laser testing unit includes a beam quality analyzer, a third total reflection mirror, and a second flip mounting base. The third total reflection mirror is mounted on the second flip mounting base, which is used to rotate the third total reflection mirror to move it into or out of the optical path of the pulsed laser beam. The third total reflection mirror reflects the pulsed laser beam into the beam quality analyzer, which is positioned in the reflected optical path of the third total reflection mirror and is used to measure the laser power on the surface of the sample under test and the shape and diameter of the laser spot on the surface of the sample under test. Raman spectroscopy signal separation and acquisition unit: The optical path of the Raman scattered light collected by the beam expander unit is set in the transmission direction of the beam separation unit to eliminate Rayleigh scattered light excited by the pulsed laser beam on the surface of the sample to be tested; Spectrometer unit: The optical path of the Raman scattered light collected by the beam expander unit is set at the focal position of the Raman spectral signal separation and acquisition unit, and is used to receive the Raman scattered light and convert the Raman scattered light signal into a Raman scattered electrical signal; Computer control unit: electrically connected to the laser emitting unit, used to adjust the laser emission parameters of the laser emitting unit; electrically connected to the automatic displacement testing unit, used to adjust the position of the sample to be tested on the automatic displacement testing unit; electrically connected to the spectrometer unit, used to adjust the spectral acquisition parameters of the spectrometer unit, and used to acquire the Raman scattering electrical signal output by the spectrometer unit, and plot the Raman spectrum based on the Raman scattering electrical signal; Microscopic imaging unit: disposed between the beam separation unit and the beam expander unit, used to acquire surface image information of the sample to be tested; the microscopic imaging unit includes a microscopic imaging camera, a long-pass filter and a first flip mounting base, the long-pass filter is mounted on the first flip mounting base, and the first flip mounting base is used to rotate the long-pass filter to move it into or out of the optical path of the pulsed laser beam; The computer control unit is electrically connected to the microscopic imaging unit and is used to adjust the microscopic imaging parameters of the microscopic imaging unit, and to acquire surface image information of the sample under test collected by the microscopic imaging unit, and to determine the ablation status of the sample under test based on the surface image information.

2. The laser ablation threshold testing device based on Raman spectroscopy according to claim 1, characterized in that, The laser emitting unit includes a pulsed laser, a laser attenuator, a first total reflection mirror, and a second total reflection mirror. The laser attenuator is disposed at the output port of the pulsed laser and is used to change the pulse energy of the pulsed laser beam. The first total reflection mirror is disposed in the output optical path of the laser attenuator, and the second total reflection mirror is disposed in the reflected optical path of the first total reflection mirror. Both the first and second total reflection mirrors are used to change the direction of the pulsed laser beam.

3. The laser ablation threshold testing device based on Raman spectroscopy according to claim 1, characterized in that, The beam expander unit includes a zoom lens, a fixed lens, and a compensation lens arranged sequentially along the optical path of the pulsed laser beam. By changing the relative positions of the zoom lens, the fixed lens, and the compensation lens, the magnification and focal length of the beam expander unit can be adjusted.

4. The laser ablation threshold testing device based on Raman spectroscopy according to claim 1, characterized in that, The Raman spectral signal separation and acquisition unit includes a collecting lens and a high-pass filter arranged sequentially along the optical path of the Raman scattered light collected by the beam expander unit. The collecting lens is used to couple the Raman scattered light into the spectrometer unit, and the high-pass filter is used to eliminate Rayleigh scattered light excited by the pulsed laser beam on the surface of the sample to be tested.

5. A method for testing the laser ablation threshold based on Raman spectroscopy, using the laser ablation threshold testing device based on Raman spectroscopy as described in any one of claims 1-4, characterized in that, Includes the following steps: S1: Determine the ablation test origin on the surface of the sample to be tested, and set the test grid based on the ablation test origin; S2: Obtain the initial microscopic image of each test point in the test grid and the initial Raman signal of each test point; S3: Select a test point, irradiate the test point with a pulsed laser beam, adjust and record the laser power and spot shape of the sample surface at the test point, take a microscopic image of the sample surface at the test point and obtain the Raman spectrum of the sample surface at the test point, determine the damage of the sample based on the microscopic image and the Raman spectrum, and record the laser power, spot diameter and damage state of the sample when damage occurs on the sample surface. S4: Adjust the position of the sample to be tested, change the test point, and repeat step S3 until the measurement of all test points in the test grid is completed. Based on the laser power, spot diameter and damage state of the sample to be tested measured at each test point, the laser ablation threshold of the sample to be tested is obtained.

6. The laser ablation threshold testing method based on Raman spectroscopy according to claim 5, characterized in that, Before performing step S1, the following steps are also included: The laser ablation threshold testing device was tested and adjusted to normal working condition; Raman spectra of single-crystal silicon wafers were collected to verify the performance of the Raman spectrometer unit.

7. The laser ablation threshold testing method based on Raman spectroscopy according to claim 5, characterized in that, The execution method of step S1 includes: Adjust the laser attenuator and beam expander unit to maximize the laser energy density, ablate the sample to be tested, and generate observable ablation pits on the surface of the sample. Record the location of the ablation pits and use this location as the origin of the ablation test. Multiple test points are set based on the ablation test origin, and the multiple test points are arranged horizontally and vertically to form a test grid.

8. The laser ablation threshold testing method based on Raman spectroscopy according to claim 5, characterized in that, The execution method of step S3 includes: Adjust the laser attenuator and beam expander units to gradually increase the laser power on the surface of the sample under test and decrease the diameter of the light spot on the surface of the sample under test. During the adjustment process, use a beam quality analyzer to measure and record the laser power value on the surface of the sample under test, as well as the shape and diameter of the light spot on the surface of the sample under test.

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