Method and equipment for detecting thickness and degree of modification of modified layer by laser invisible cutting

Abstract

The invention discloses a method and device for detecting the thickness and the degree of modification of a modified layer during invisible laser cutting. On the basis of the existing equipment, only one parallel detection optical path needs to be added, and the thickness and the degree of modification of the modified layer are determined by utilizing the absorption of the modified layer to a wide-spectrum light source, so that the cutting effect can be detected throughout the processing. It is only necessary to focus the detection focusing objective lens on the bottom of the material, and there is no need to perform three-dimensional scanning on the cutting layer. The detection focusing objective lens can be detected by moving simultaneously with the processing focusing objective lens. The method has the characteristics of simple operation, convenience, speed, and instant detection, and can provide feedback to the processing equipment to adjust the operating parameters of the processing equipment in real time to ensure the uniformity and consistency of the cutting.

Description

Technical Field

[0001] The present invention relates to the technical field of laser stealth cutting, and in particular to a method and device for detecting the thickness and degree of modification of a laser stealth cutting modified layer. Background Art

[0002] Transparent hard and brittle materials have excellent properties such as wide spectrum transmittance, high hardness, and corrosion resistance. Common transparent hard and brittle materials are mainly: silicon carbide, gallium nitride, glass, sapphire, diamond, etc. In the processing process, the use of mechanical tools often has the disadvantages of low processing accuracy, complex processing conditions, and inability to process the inside of the material. Laser processing has the advantages of high precision, non-contact, non-vacuum conditions, and the ability to act on the inside of the material. By regulating the light field inside the material, a long-focus deep beam and multi-focal distribution are generated, thereby improving processing efficiency, processing accuracy and energy utilization, which is of great significance for the application of hard and brittle materials. As an emerging laser cutting technology, laser invisible cutting technology has the advantages of no surface scratches, no debris slag, small heat-affected zone, and dry cutting compared with other laser cutting technologies. It can achieve zero cutting line width, fast and front-side damage-free cutting of materials such as silicon carbide, gallium nitride, glass, and sapphire. The principle of laser invisible cutting is to use an optical system to focus a pulsed (nanosecond, picosecond, femtosecond) laser beam that can penetrate the material into the interior of the material, so that a modified layer is formed in the internal material, resulting in recrystallization, dislocation and microcracks. Then, the blue film placed at the bottom of the material is unfolded. Due to the large tensile stress and compressive stress near the internal modified layer, cracks can be induced inside the material along the laser path to achieve chip separation.

[0003] Transparent hard and brittle materials have high hardness and brittleness. When using laser to cut such materials, as the thickness increases, the required thickness of the modified layer also increases accordingly. Single cutting is often not possible, so multiple scans along the thickness direction are required. In order to improve the cutting efficiency, the equipment uses axicon mirrors, spatial light modulators, diffractive optical elements, etc., and adjusts the wavefront of the incident light to a conical distribution or a multi-focal distribution. Therefore, a long focal depth and multi-focal beam can be achieved within a certain range along the direction of light transmission, thereby realizing the modification and cutting of thick materials.

[0004] Since the modified layer is inside the hard and brittle material and is distributed in three dimensions, it is difficult to detect the modified layer. In the existing laser invisible cutting quality detection methods, most of them detect the shape and position of the modified layer by cross-sectional microscopy after the cutting is completed. This method has hysteresis, cannot achieve real-time online detection, and cannot adjust the laser parameters according to the detection results.

[0005] The patent with publication number CN115138982A discloses a wafer laser invisible cutting collaborative detection method and system, which couples the laser cutting optical path and the interference detection optical path to achieve online detection of the modified layer position. However, this method requires the modification of the laser cutting optical path and cannot be applied to existing laser invisible cutting equipment. In addition, this method is only applicable to single-focus cutting equipment, not to multi-focus laser invisible cutting equipment.

[0006] The patent with publication number CN116765629A discloses a method for detecting the shape and position of modified layers by laser stealth cutting. A new set of laser detection optical paths is introduced outside the processing optical path, and a photoelectric detector is used to detect the change in the polarization state of scattered light to detect the quality of the modified layer of the laser stealth cutting sample. However, this method requires three-dimensional scanning of the processing path and is only applicable to single-focus cutting equipment, not to multi-focus laser stealth cutting equipment. In addition, this method requires the replacement of lasers with different wavelengths when cutting a variety of different materials. Summary of the invention

[0007] In order to solve the technical problems existing in the prior art, the present invention provides a method for detecting the thickness and degree of modification of a laser invisible cutting modified layer, which is simple to operate, convenient and fast, does not require 3D modeling, can be applied to single-focus, multi-focus, and telephoto optical path systems, and realizes real-time monitoring and real-time feedback of the thickness and degree of modification of the modified layer, and has the characteristics of high detection accuracy and a wide range of applicable materials. In addition, the present invention also provides a device for the above detection method.

[0008] In order to achieve the above object, the present invention adopts the following technical solutions:

[0009] A first aspect of the present invention provides a method for detecting the thickness and degree of modification of a laser stealth cutting modified layer, comprising the following steps:

[0010] S1. A wide-spectrum halogen light source is used as the detection light source. The detection light beam emitted by the halogen light source passes through the detection light path, and then forms a focus through the detection focusing lens and focuses on the bottom of the unprocessed area of ​​the sample. Since the objective lens focuses on the bottom of the material, the detection light beam passes through the entire sample and focuses at the bottom of the sample;

[0011] The reflected light at the focus of the bottom of the unprocessed area of ​​the sample returns to the detection focusing objective lens along the original optical path, becomes parallel light after passing through the detection focusing objective lens, and is then divided into two parts. One part enters the imaging component, and the imaging component transmits the imaging information to the host computer. The other part is collected by the detection optical fiber to the spectrometer. The spectrometer obtains the reflection spectrum E0(λ) of the bottom of the unprocessed area of ​​the sample and transmits it to the host computer for storage.

[0012] S2. Move the focus of the detection light source to the modified processing area of ​​the sample. The detection focusing objective lens and the processing focusing objective lens remain relatively still. During the entire laser invisible cutting process, the sample moves while the processing focusing objective lens is still. The detection focusing objective lens can always measure the modified processing area of ​​the sample in real time.

[0013] S3, the laser emits a laser beam which is irradiated on the processing focusing objective lens through a reflector and focused inside the sample. The upper computer controls the output power and repetition frequency of the laser and the moving speed of the moving platform for placing the sample. The focus of the laser beam moves inside the sample to achieve laser invisible cutting of the sample, thereby obtaining a modified layer.

[0014] S4. During the laser invisible cutting process, the detection beam emitted by the halogen light source passes through the modified layer inside the sample and is focused on the bottom of the modified processing area of ​​the sample. Since the detection focusing objective lens and the processing focusing objective lens are relatively stationary in space, as the mobile platform moves, part of the detection beam reflected by the bottom of the newly modified processing area of ​​the sample is collected in real time to the spectrometer through the detection optical fiber. The spectrometer obtains the reflection spectrum E1(λ) of the bottom of the modified processing area of ​​the sample in real time and transmits it to the host computer for storage;

[0015] S5. Compare and calculate the reflection spectrum of the bottom of the modified area of ​​the sample obtained in real time with the reflection spectrum of the bottom of the unprocessed area of ​​the sample to obtain the absorption spectrum N(λ) of the modified layer inside the sample, N(λ) = 1-E1(λ) / E0(λ). According to the size of N(λ), the thickness and degree of modification of the modified layer for laser invisible cutting are determined.

[0016] Furthermore, the detection focusing objective lens and the processing focusing objective lens are coaxially arranged. During the processing, the real-time analysis results of the modified layer inside the sample are obtained based on the absorption spectrum of the modified layer inside the sample. The output power and repetition frequency of the laser and the moving speed of the moving platform are controlled by the host computer, and the thickness and modification degree of the modified layer inside the sample are adjusted and controlled in real time, thereby realizing real-time monitoring and real-time feedback during the processing, and ensuring the uniformity and consistency of cutting.

[0017] Furthermore, the reflected light from the bottom of the unprocessed area of ​​the sample returns to the detection focusing objective lens along the original optical path and becomes parallel light. The parallel light is formed into a reflected light beam and a transmitted light beam through the first semi-transparent and semi-reflective mirror. The reflected light beam is focused on the imaging component, which is a CCD camera. The lens focuses the reflected light beam on the photosensitive plane of the CCD camera. This optical path is called the imaging optical path; the transmitted light beam is collected to the spectrometer through the detection optical fiber.

[0018] Furthermore, the detection optical fiber is a micro-area optical fiber, one end of which is a port for receiving a transmitted light beam, which is fixed by an optical fiber holder and is used to collect reflected light within a diameter range of 10 μm at the near axis of the focusing objective lens, thereby being able to accurately measure the material reflection spectrum within a relatively small range.

[0019] Furthermore, the other end of the micro-area optical fiber is provided with two interfaces, one interface is used to connect the spectrometer, and the other interface is used to connect the illumination light source, and the light beam emitted by the illumination light source is introduced into the detection focusing objective lens through the micro-area optical fiber. The structure of the micro-area optical fiber is: 20 illumination optical fibers with a core diameter of 100μm surround the measurement core. The use of micro-area illumination technology and the adjustment function of the detection focusing objective lens can accurately mark the measurement position in the field of view, and the introduction of the micro-area optical fiber at the near axis of the detection light path can collect the reflected light within the range of only 10μm in diameter at the near axis of the detection focusing objective lens, so that the material reflection spectrum in a relatively small range can be accurately measured, and the detection of the modified layer within the range of the light spot can be realized, thereby improving the detection accuracy.

[0020] Furthermore, the detection optical path includes a collimator, a filter, and a second semi-transparent and semi-reflective mirror. The detection light beam emitted by the halogen light source is introduced into the collimator through the optical fiber. The collimator collimates the emitted light in the optical fiber and converts it into parallel light, and then passes through the filter to allow the long-wave band to pass through, and finally irradiates the detection focusing objective lens through the second semi-transparent and semi-reflective mirror.

[0021] A second aspect of the present invention provides a device for the above-mentioned detection method, comprising a processing light path mounting plate, a detection light path mounting plate, a detection light path adjustment plate, a connecting frame, a mobile platform and a host computer;

[0022] The processing light path installation plate and the detection light path installation plate are connected via the connecting frame;

[0023] A reflector is mounted on the processing light path mounting plate through a bracket, a first light-transmitting hole is opened on the processing light path mounting plate, a processing focusing objective lens is arranged directly below the first light-transmitting hole, the processing focusing objective lens is mounted on the processing light path mounting plate through a first fixing bracket, and a laser beam emitted by a laser is irradiated on the processing focusing objective lens through the reflector;

[0024] A detection light path adjustment plate is provided above the detection light path mounting plate, and the detection light path adjustment plate can move relative to the detection light path mounting plate along the X-axis and Y-axis directions, and a detection light path, an imaging component, a lens and a support rod are provided on the detection light path adjustment plate, and an optical fiber holder and a first semi-transparent and semi-reflective mirror are provided on the support rod in sequence from top to bottom, an end of one end of the detection optical fiber is fixedly mounted on the optical fiber holder, and a spectrometer is connected to the other end of the detection optical fiber, and second light transmission holes are correspondingly provided on the detection light path adjustment plate and the detection light path mounting plate, and a detection focusing objective lens is provided directly below the second light transmission hole, and the detection The measuring focusing objective lens is mounted on the detection optical path adjustment plate through a second fixing bracket, the moving platform is located below the processing focusing objective lens and the detection focusing objective lens, the detection light beam emitted by the halogen light source is irradiated on the detection focusing objective lens through the detection optical path, and then passes through the sample on the moving platform and is focused to the bottom of the sample through the detection focusing objective lens, the detection light beam reflected by the bottom of the sample returns to the detection focusing objective lens along the original optical path and becomes parallel light, the parallel light forms a reflected light beam and a transmitted light beam through a first semi-transparent and semi-reflective mirror, the reflected light beam is focused to the imaging component through a lens, and the transmitted light beam is collected to the spectrometer through the end of the detection optical fiber;

[0025] The spectrometer, the imaging component and the laser are respectively connected to the host computer.

[0026] Furthermore, the other end of the detection optical fiber is also connected to an illumination light source, and the light beam emitted by the illumination light source is guided to the detection focusing objective lens through the detection optical fiber.

[0027] Furthermore, the detection optical fiber is a micro-area optical fiber, which is used to collect and detect reflected light within a diameter range of 10 μm at the near axis of the focusing objective lens.

[0028] Furthermore, the detection optical path includes a collimator, a filter, and a second semi-transparent and semi-reflective mirror. The detection light beam emitted by the halogen light source is introduced into the collimator via an optical fiber. The collimator collimates the emitted light in the optical fiber and converts it into parallel light, which then passes through a filter to allow a long-wave band to pass through, and finally is irradiated to the detection focusing objective lens via a second semi-transparent and semi-reflective mirror.

[0029] Compared with the prior art, the present invention has the following beneficial effects:

[0030] 1. On the basis of the existing equipment, the present invention only needs to add another parallel detection light path, and use the absorption of the modified layer to the wide-spectrum light source to determine the thickness and degree of modification of the modified layer, so as to achieve a fully detectable cutting effect during the processing. The detection method is instantaneous and can be fed back to the processing equipment in real time, so as to adjust the operating parameters of the processing equipment in real time to ensure the uniformity and consistency of cutting.

[0031] 2. The detection light path in the present invention does not use laser as the detection light source, but uses a halogen light source with a wide spectrum as the detection light source, so the detection light source does not need to be changed due to changes in product materials.

[0032] 3. In the present invention, the modification depth and modification degree are detected by utilizing the absorption characteristics of the modified layer for incident light. It is only necessary to focus the detection focusing lens on the bottom of the sample material, and there is no need to perform three-dimensional scanning on the cutting layer. The detection focusing lens can be detected by moving simultaneously with the processing focusing lens, which is simple to operate and convenient and fast.

[0033] 4. The present invention utilizes micro-area indication lighting technology and a three-dimensional position adjuster for the detection focusing objective lens (position adjustment of the detection focusing objective lens along the XYZ axis) to accurately mark the measurement position in the field of view.

[0034] 5. In the present invention, a micro-area optical fiber is introduced at the near-axis of the detection light path (20 illumination optical fibers with a core diameter of 100 μm are surrounded by the measurement core). After being focused by the detection focusing objective lens, the reflected light within the near-axis diameter of only 10 μm can be collected, thereby accurately measuring the material reflection spectrum within a relatively small range, realizing the detection of the modified layer within the light spot range, and improving the detection accuracy.

[0035] 6. The present invention utilizes the measurement technology to first measure the reflection spectrum of the unprocessed area of ​​the sample for the detection light and store the data. Then, the measurement area is moved to the modified processing area of ​​the sample through the three-dimensional adjuster of the detection focusing objective lens. Then, the detection focusing objective lens is fixed. At this time, the detection focusing objective lens and the processing focusing objective lens are relatively still. Since the entire invisible cutting equipment moves with the sample while the objective lens is still, the detection focusing objective lens can always measure the reflection spectrum of the newly processed area of ​​the sample, and has the characteristics of real-time detection.

[0036] 7. In the present invention, by real-time sampling of the modified processed area of ​​the sample and comparing the data with the reflective spectrum of the unprocessed area of ​​the sample in a computer, the absorption spectrum of the modified layer can be obtained. The absorption spectrum contains two information: spectrum and absorption intensity. The thickness (absorption intensity) and modification degree (absorption spectrum position) of the modified layer in the new processed area can be determined by using the accumulated data in the stealth cutting process. Therefore, the present invention can detect the thickness and modification degree of the modified layer in real time.

[0037] 8. In the present invention, the results of the analysis of the modified layer during the processing can be fed back to the laser invisible cutting system in real time. By changing the moving speed of the mobile platform and the laser pulse energy and pulse repetition frequency, the modified layer can be ultimately controlled to the optimal thickness and modification degree. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] The present invention is further described in detail below with reference to the accompanying drawings and specific embodiments.

[0039] Figure 1 It is a flow chart of the method for detecting the thickness and degree of modification of the laser invisible cutting modified layer in the present invention;

[0040] Figure 2 It is the main optical path diagram used in the detection process of the thickness and modification degree of the modified layer by laser stealth cutting in the present invention;

[0041] Figure 3 It is a schematic diagram of the structure of the device used for the detection method of the thickness and modification degree of the modified layer by laser stealth cutting in the present invention;

[0042] Figure 4 is the reflection spectrum of glass material under different processing powers;

[0043] Figure 5 is the absorption spectrum N(λ) of the modified layer in the glass material at different powers.

[0044] Among them, the specific figure markings are: laser 1, processing light path mounting plate 2, reflector 3, processing focusing objective lens 4, first fixed frame 5, detection light path mounting plate 6, detection light path adjustment plate 7, imaging component 8, lens 9, spectrometer 10, illumination light source 11, detection optical fiber 12, optical fiber holder 13, first semi-transparent and semi-reflective mirror 14, support rod 15, halogen light source 16, collimator 17, filter 18, second semi-transparent and semi-reflective mirror 19, detection focusing objective lens 20, second fixed frame 21, connecting frame 22, mobile platform 23, host computer 24, sample 25. DETAILED DESCRIPTION

[0045] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0046] Example 1

[0047] A method for detecting the thickness and degree of modification of a laser invisible cutting modified layer, such as Figure 1 As shown, the following steps are included, and the main optical path of the detection process is as follows Figure 2 As shown:

[0048] S1. Determine the detection position using CCD imaging and micro-area imaging technology, and move the detection focusing objective lens 20 to the unprocessed area of ​​the sample 25.

[0049] S2. A wide-spectrum halogen light source 16 is used as a detection light source. The detection light beam emitted by the halogen light source is introduced into a collimator 17 through an optical fiber. The collimator 17 collimates the emitted light in the optical fiber and converts it into parallel light. The long-wave band is then passed through an optical filter 18. The long-wave band is then irradiated to a detection focusing objective lens 20 through a second semi-transparent and semi-reflective mirror 19. Finally, the detection focusing objective lens 20 forms a focus and focuses on the bottom of the unprocessed area of ​​the sample 25. Since the objective lens is focused on the bottom of the material, the detection light beam passes through the entire sample 25 and focuses on the bottom of the sample 25.

[0050] S3. The reflected light at the focal point at the bottom of the unprocessed area of ​​the sample 25 is returned to the detection focusing objective lens 20 along the original optical path and becomes parallel light. The parallel light is formed into a reflected light beam and a transmitted light beam through the first semi-transparent and semi-reflective mirror 14. The reflected light beam is focused to the imaging component 8 through the lens 9. The imaging component 8 transmits the imaging information to the host computer 24. The imaging component 8 is a CCD camera. The lens 9 focuses the reflected light beam on the photosensitive plane of the CCD camera. This optical path is called the imaging optical path; the transmitted light beam is collected to the spectrometer 10 through the detection optical fiber 12. The spectrometer 10 obtains the reflected spectrum of the bottom of the unprocessed area of ​​the sample 25, which is used as a reference spectrum and is transmitted to the host computer 24 for storage.

[0051] Among them, the detection optical fiber 12 is a micro-area optical fiber, one end of which is a port for receiving the transmitted light beam. The port is fixed by an optical fiber holder 13 and is used to collect the reflected light within a diameter range of 10μm at the near axis of the focusing objective lens 20, so as to accurately measure the material reflection spectrum within a relatively small range.

[0052] The other end of the micro-area optical fiber is provided with two interfaces, one interface is used to connect the spectrometer 10, and the other interface is used to connect the illumination light source 11. The light beam emitted by the illumination light source 11 is introduced into the detection focusing objective lens 20 through the micro-area optical fiber. The structure of the micro-area optical fiber is: 20 illumination optical fibers with a core diameter of 100 μm surround the measurement core. The use of micro-area illumination technology and the three-dimensional position adjustment function of the detection focusing objective lens 20 can accurately mark the measurement position in the field of view, and the introduction of the micro-area optical fiber at the near axis of the detection light path can collect the reflected light within the range of only 10 μm in diameter at the near axis of the detection focusing objective lens 20, so that the material reflection spectrum within a relatively small range can be accurately measured, and the detection of the modified layer within the light spot range can be realized, and the detection accuracy is improved.

[0053] S4. Move the focus of the detection light source (i.e., the detection focusing objective lens 20) to the modified processing area of ​​the sample 25. The detection focusing objective lens 20 and the processing focusing objective lens 4 remain relatively still. During the entire laser invisible cutting process, the sample 25 moves while the processing focusing objective lens 4 is in a stationary state. The detection focusing objective lens 20 can always measure the modified processing area of ​​the sample 25 in real time.

[0054] S5. The laser beam emitted by the laser 1 is irradiated onto the processing focusing objective lens 4 through the reflector 3 and focused into the inside of the sample 25. The upper computer 24 controls the output power and repetition frequency of the laser 1 and the moving speed of the moving platform 23 for placing the sample 25. The focus of the laser beam moves inside the sample 25 to achieve laser invisible cutting of the sample 25, thereby obtaining a modified layer.

[0055] S6. During the laser invisible cutting process, the detection light beam emitted by the halogen light source 16 passes through the internal modified layer of the sample 25 and is focused on the bottom of the modified processing area of ​​the sample 25. Since the detection focusing objective lens 20 and the processing focusing objective lens 4 are relatively stationary in space, as the moving platform 23 moves, part of the detection light beam reflected by the bottom of the newly modified processing area of ​​the sample 25 is collected in real time to the spectrometer 10 via the detection optical fiber 12. The spectrometer 10 obtains the reflection spectrum E1(λ) of the bottom of the modified processing area of ​​the sample 25 in real time and transmits it to the host computer 24 for storage.

[0056] S7. Compare and calculate the reflection spectrum of the bottom of the modified area of ​​sample 25 obtained in real time with the reflection spectrum of the bottom of the unprocessed area of ​​sample 25 to obtain the absorption spectrum N(λ) of the modified layer inside sample 25, N(λ) = 1-E1(λ) / E0(λ). According to the size of N(λ), the thickness and degree of modification of the modified layer for laser invisible cutting are determined.

[0057] The detection focusing objective lens 20 is coaxially arranged with the processing focusing objective lens 4. During the processing, the real-time analysis result of the modified layer inside the sample 25 is obtained according to the absorption spectrum of the modified layer inside the sample 25. Then, the output power and repetition frequency of the laser 1 and the moving speed of the moving platform 23 are controlled by the upper computer 24, and the thickness and modification degree of the modified layer inside the sample 25 are adjusted and controlled in real time, thereby realizing real-time monitoring and real-time feedback during the processing and ensuring the uniformity and consistency of cutting.

[0058] Example 2

[0059] A device for detecting the thickness and degree of modification of a laser invisible cutting modified layer, such as Figure 2 and Figure 3 As shown, it includes a processing optical path mounting plate 2, a detection optical path mounting plate 6, a detection optical path adjustment plate 7, a connecting frame 22, a mobile platform 23 and a host computer 24;

[0060] The processing optical path mounting plate 2 and the detection optical path mounting plate 6 are connected via a connecting frame 22;

[0061] A reflector 3 is mounted on the processing light path mounting plate 2 through a bracket, a first light transmission hole is opened on the processing light path mounting plate 2, a processing focusing objective lens 4 is arranged directly below the first light transmission hole, and the processing focusing objective lens 4 is mounted on the processing light path mounting plate 2 through a first fixing bracket 5, and the laser beam emitted by the laser 1 is irradiated on the processing focusing objective lens 4 through the reflector 3;

[0062] A detection light path adjustment plate 7 is provided above the detection light path mounting plate 6. The detection light path adjustment plate 7 can move relative to the detection light path mounting plate 6 along the X-axis and Y-axis directions. The detection light path adjustment plate 7 is provided with a detection light path, an imaging component 8, a lens 9 and a support rod 15. The detection light path includes a collimator 17, a filter 18, and a second semi-transparent and semi-reflective mirror 19. The collimator 17 and the filter 18 are installed on the detection light path adjustment plate 7 from left to right. The support rod 15 is provided with an optical fiber holder 13, a first semi-transparent and semi-reflective mirror 14 and a second semi-transparent and semi-reflective mirror 19 in sequence from top to bottom. The end of one end of the detection optical fiber 12 is fixedly mounted on the optical fiber holder 13. The other end of the detection optical fiber 12 is provided with two interfaces, which are respectively connected to the spectrometer 10 and the illumination light source 11. The detection light path adjustment plate 7 and the detection light path A second light-transmitting hole is correspondingly opened on the mounting plate 6, and a detection focusing objective lens 20 is arranged directly below the second light-transmitting hole. The detection focusing objective lens 20 is mounted on the detection light path adjustment plate 7 through a second fixing frame 21, and the movable platform 23 is located below the processing focusing objective lens 4 and the detection focusing objective lens 20. The detection light beam emitted by the wide-spectrum halogen light source 16 is introduced into the collimator 17 via the optical fiber, and the collimator 17 collimates the emitted light in the optical fiber and converts it into parallel light, and then passes through the long-wave band through the filter 18, and finally irradiates the detection focusing objective lens 20 through the second semi-transparent and semi-reflective mirror 19, and then passes through the sample 25 on the movable platform 23 through the detection focusing objective lens 20 and is focused to the bottom of the sample 25, and the light beam emitted by the illumination light source 11 is introduced into the detection focusing objective lens 20 via the detection optical fiber 12. The detection light beam reflected from the bottom of the sample 25 returns to the detection focusing objective lens 20 along the original light path and becomes parallel light. The parallel light forms a reflected light beam and a transmitted light beam through the first semi-transparent and semi-reflective mirror 14. The reflected light beam is focused to the imaging component 8 through the lens 9. The imaging component 8 is a CCD camera. The lens 9 focuses the reflected light beam on the photosensitive plane of the CCD camera. This light path is called the imaging light path. The transmitted light beam is collected to the spectrometer 10 through the end of the detection optical fiber 12.

[0063] Among them, the spectrometer 10, the imaging component 8, and the laser 1 are respectively connected to the host computer 24. The imaging component 8 transmits the imaging information to the host computer 24. The host computer 24 can control the output power and repetition frequency of the laser 1. The spectrometer 10 transmits the real-time reflection spectrum to the host computer 24 for storage.

[0064] The detection optical fiber 12 is a micro-area optical fiber, and the structure of the micro-area optical fiber is as follows: 20 illumination optical fibers with a core diameter of 100 μm surround the measurement core, and are used to collect and detect reflected light within a diameter range of 10 μm at the proximal axis of the focusing objective lens 20 .

[0065] The first fixing frame 5 and the second fixing frame 21 are both provided with a coarse adjustment knob and a fine adjustment knob for the objective lens, and the machining focusing objective lens 4 and the detection focusing objective lens 20 are moved up and down along the Z axis through the corresponding coarse adjustment knob and the fine adjustment knob for the objective lens.

[0066] The feasibility of the technical solution in the invention is confirmed by the laser invisible cutting experiment on glass materials. During the processing, the host computer 24 controls the laser 1 to output different powers, and the spectrometer 10 can obtain the following information: Figure 4 The reflectance spectrum is calculated and generated in the host computer 24 Figure 5 Absorption spectrum of material modified layer. The unprocessed area of ​​the material has no internal defects and no modified layer. Figure 4 When the laser acts on the inside of the material, the material's absorption of the detection light increases due to the generation of the modified layer and defects, causing the reflected light intensity to decrease. With the increase of laser energy, the thickness of the modified layer and the degree of modification also change to varying degrees, which is reflected in Figure 4 Reduction of reflected light intensity. By calculating the ratio of the reflection intensity of the material modified processing area to the reflection intensity of the material unprocessed area under different processing powers in the host computer 24, the absorption spectrum of the material modified layer under different powers can be obtained. The experimental study and comparison found that when the power of the laser 1 is 15w, the separation effect of the processed glass material is the best, so the absorption rate of the modified layer is selected as a reference to detect and determine the modification effect of the material during the processing process.

[0067] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A method for detecting the thickness and degree of modification of a laser invisible cutting modified layer, characterized in that: The following steps are involved: S1. A halogen light source is used as a detection light source. The detection light beam emitted by the halogen light source passes through the detection light path and is then focused to the bottom of the unprocessed area of ​​the sample by the detection focusing objective lens. The detection light beam reflected by the bottom of the unprocessed area of ​​the sample is divided into two parts. One part enters the imaging component, and the imaging component transmits the imaging information to the host computer. The other part is collected to the spectrometer through the detection optical fiber. The spectrometer obtains the reflection spectrum of the bottom of the unprocessed area of ​​the sample and transmits it to the host computer for storage. S2, moving the focus of the detection light source to the sample modification processing area, and keeping the detection focusing lens and the processing focusing lens relatively still; S3, the laser beam emitted by the laser is focused into the sample through the processing focusing lens, the moving platform for placing the sample is controlled to move, the focus of the laser beam moves inside the sample, and the laser invisible cutting of the sample is realized, thereby obtaining a modified layer; S4. During the laser stealth cutting process, the detection beam emitted by the halogen light source passes through the modified layer inside the sample and is focused on the bottom of the modified processing area of ​​the sample. Part of the detection beam reflected by the bottom of the modified processing area of ​​the sample is collected in real time to the spectrometer through the detection optical fiber. The spectrometer obtains the reflection spectrum of the bottom of the modified processing area of ​​the sample in real time and transmits it to the host computer for storage; S5, comparing and calculating the reflection spectrum of the bottom of the modified area of ​​the sample obtained in real time with the reflection spectrum of the bottom of the unprocessed area of ​​the sample to obtain the absorption spectrum of the modified layer inside the sample; The detection focusing objective lens and the processing focusing objective lens are coaxially arranged. During the processing, the real-time analysis result of the modified layer inside the sample is obtained according to the absorption spectrum of the modified layer inside the sample. Then, the output power and repetition frequency of the laser and the moving speed of the moving platform are controlled by the host computer to adjust and control the thickness and modification degree of the modified layer inside the sample in real time.

2. The method for detecting the thickness and degree of modification of the laser invisible cutting modified layer according to claim 1, characterized in that: The detection light beam reflected from the bottom of the unprocessed area of ​​the sample returns to the detection focusing objective lens along the original optical path and becomes parallel light. The parallel light passes through the first semi-transparent and semi-reflective mirror to form a reflected light beam and a transmitted light beam. The reflected light beam is focused to the imaging component, and the transmitted light beam is collected to the spectrometer through the detection optical fiber.

3. The method for detecting the thickness and degree of modification of the laser stealth cutting modified layer according to claim 2, characterized in that: The detection optical fiber is a micro-area optical fiber, one end of which is a port for receiving a transmitted light beam, and the port is fixed by an optical fiber holder and is used to collect and detect reflected light within a diameter range of 10 μm at the proximal axis of the focusing objective lens.

4. The method for detecting the thickness and degree of modification of the laser stealth cutting modified layer according to claim 3, characterized in that: The other end of the micro-area optical fiber is provided with two interfaces, one interface is used to connect to the spectrometer, and the other interface is used to connect to the illumination light source. The light beam emitted by the illumination light source is introduced into the detection focusing objective lens through the micro-area optical fiber.

5. The method for detecting the thickness and degree of modification of the laser stealth cutting modified layer according to claim 1, characterized in that: The detection optical path includes a collimator, a filter, and a second semi-transparent and semi-reflective mirror. The detection light beam emitted by the halogen light source is introduced into the collimator through the optical fiber. The collimator collimates the emitted light in the optical fiber and converts it into parallel light, and then passes through the filter to allow the long-wave band to pass through, and finally irradiates the detection focusing objective lens through the second semi-transparent and semi-reflective mirror.

6. A device for the detection method according to any one of claims 1 to 5, characterized in that: It includes a processing optical path installation plate, a detection optical path installation plate, a detection optical path adjustment plate, a connecting frame, a mobile platform and a host computer; The processing light path installation plate and the detection light path installation plate are connected via the connecting frame; A reflector is mounted on the processing light path mounting plate through a bracket, a first light-transmitting hole is opened on the processing light path mounting plate, a processing focusing objective lens is arranged directly below the first light-transmitting hole, the processing focusing objective lens is mounted on the processing light path mounting plate through a first fixing bracket, and a laser beam emitted by a laser is irradiated on the processing focusing objective lens through the reflector; A detection light path adjustment plate is provided above the detection light path mounting plate, and the detection light path adjustment plate can move relative to the detection light path mounting plate along the X-axis and Y-axis directions, and a detection light path, an imaging component, a lens and a support rod are provided on the detection light path adjustment plate, and an optical fiber holder and a first semi-transparent and semi-reflective mirror are provided on the support rod in sequence from top to bottom, an end of one end of the detection optical fiber is fixedly mounted on the optical fiber holder, and a spectrometer is connected to the other end of the detection optical fiber, and second light transmission holes are correspondingly provided on the detection light path adjustment plate and the detection light path mounting plate, and a detection focusing objective lens is provided directly below the second light transmission hole, and the detection The measuring focusing objective lens is mounted on the detection optical path adjustment plate through a second fixing bracket, the moving platform is located below the processing focusing objective lens and the detection focusing objective lens, the detection light beam emitted by the halogen light source is irradiated on the detection focusing objective lens through the detection optical path, and then passes through the sample on the moving platform and is focused to the bottom of the sample through the detection focusing objective lens, the detection light beam reflected by the bottom of the sample returns to the detection focusing objective lens along the original optical path and becomes parallel light, the parallel light forms a reflected light beam and a transmitted light beam through a first semi-transparent and semi-reflective mirror, the reflected light beam is focused to the imaging component through a lens, and the transmitted light beam is collected to the spectrometer through the end of the detection optical fiber; The spectrometer, the imaging component and the laser are respectively connected to the host computer.

7. The device according to claim 6, characterized in that The other end of the detection optical fiber is also connected to an illumination light source, and the light beam emitted by the illumination light source is guided to the detection focusing objective lens through the detection optical fiber.

8. The device according to claim 7, characterized in that The detection optical fiber is a micro-area optical fiber, which is used to collect and detect reflected light within a diameter range of 10 μm at the near axis of the focusing objective lens.

9. The device according to claim 6, characterized in that The detection optical path includes a collimator, a filter, and a second semi-transparent and semi-reflective mirror. The detection light beam emitted by the halogen light source is introduced into the collimator through the optical fiber. The collimator collimates the emitted light in the optical fiber and converts it into parallel light, and then passes through the filter to allow the long-wave band to pass through, and finally irradiates the detection focusing objective lens through the second semi-transparent and semi-reflective mirror.

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