Manufacturing method for generating DIC speckles in situ on base material at high temperature

Abstract

The invention provides a manufacturing method for in-situ generation of DIC speckles on a base material at high temperature, which comprises the following steps: S1, material surface pretreatment: pretreating the surface of a material to be processed, including surface alkaline oil removal and acid pickling activation, and removing the surface of a normal-temperature oxide layer of the material; s2, a protective film is selected and attached, wherein a surface protective film is selected and attached; s3, speckle processing on the protective film: speckle processing is carried out on the protective film, the spot diameter and the ablation depth are accurately controlled, and the surface of the base material is prevented from being damaged; s4, blackening treatment is carried out to generate speckles, specifically, after speckle processing is completed, a blackening solution is selected, stirring is carried out within the range of 35-40 DEG C, solution exchange in the holes is promoted, and DIC speckles are completely generated on the base material at the laser processing holes; and S5, removing the protective film and performing post-treatment. According to the invention, by accurately controlling the generation rate and position of the elements of the base material, speckles with uniform sizes can be formed on the surface of the sample, so that the accuracy and repeatability of measurement are greatly improved, and measurement errors caused by inconsistent speckle sizes are reduced.

Description

Technical Field

[0001] The invention relates to the technical field of metal processing methods, and in particular to a method for producing in-situ DIC speckles generated by a substrate at high temperature. Background Art

[0002] Principle of traditional DIC speckle technology: Traditional DIC speckle technology is through the calculation and analysis of two digital images before and after the specimen is deformed. The region of interest in the image before deformation is gridded, and each sub-region is regarded as rigid motion, and the deformation information of the region is obtained through correlation calculation. The specific operation is to perform correlation calculation for each sub-region according to the pre-defined correlation function, and find the region with the largest correlation coefficient with the sub-region in the deformed image, that is, the position of the sub-region after deformation, and then obtain the displacement of the sub-region. The full-field deformation information can be obtained by calculating all sub-regions. Speckle types and traditional production methods: Speckle types mainly include natural speckle and artificial speckle. Artificial speckle is to process the surface of the sample to be tested by artificial means to attach spots to it. Common production methods include spraying, chemical vapor deposition, nanoparticle spraying, ultraviolet lithography, etc.

[0003] The traditional production method has the following defects:

[0004] 1. Spraying method: The speckle size produced by acrylic paint, polyurethane paint and other coatings is relatively large, and the smallest can only reach the sub-millimeter level. It cannot meet the requirements for high-precision measurement of small deformations, and the measurement resolution is limited. In addition, in special environments such as high temperature, high humidity, and strong corrosion, the speckle of artificially sprayed paint is prone to fading, falling off, and deformation, which seriously affects the accuracy and reliability of the measurement.

[0005] 2. Chemical vapor deposition method: The speckle prepared by this method is greatly affected by the surface properties of the sample to be tested, and the process is complex, costly, and inefficient. At the same time, the preparation process may change the physical and chemical properties of the surface of the sample to be tested, causing adverse effects on the sample.

[0006] 3. Nanoparticle spraying method: Affected by the agglomeration of nanoparticles, the size and shape of the prepared speckle are uneven, and the adhesion between the particles and the surface of the object is weak, resulting in reduced measurement accuracy. In addition, nanoparticles are sensitive to the environment and the speckle is difficult to control.

[0007] 4. Ultraviolet photolithography: Although it can produce submicron speckles, it has extremely high requirements on equipment, the production process is extremely complicated, the cost is too high, and it is not conducive to large-scale application. Summary of the invention

[0008] In view of the above problems, the present invention provides a method for in-situ generating DIC speckle on a substrate at high temperature.

[0009] To solve the above problems, the technical solution adopted by the present invention is as follows:

[0010] A method for fabricating DIC speckles in-situ on a substrate at high temperature, comprising the following steps:

[0011] S1. Surface pretreatment of the material: Pretreat the surface of the material to be processed, including alkaline degreasing and pickling activation of the surface, and remove the surface of the material's ambient-temperature oxide layer;

[0012] S2. Selection and lamination of the protective film: Select a surface protective film and laminate it;

[0013] S3. Speckle processing on the protective film: Perform speckle processing on the protective film, precisely control the spot diameter and ablation depth, and avoid damaging the surface of the substrate;

[0014] S4. Blackening treatment to generate speckles: After the speckle processing is completed, select a blackening solution, stir it within the range of 35 - 40 °C to promote the exchange of the solution in the pores, and enable the substrate at the laser-processed holes to completely generate DIC speckles;

[0015] S5. Removal of the protective film and post-treatment: Remove the protective film and perform post-treatment.

[0016] Preferably, in the step S1, the surface pretreatment of the material includes alkaline degreasing and acidic activation. The alkaline degreasing uses a solution of NaOH + surfactant, at a temperature of 70 ± 5 °C, with ultrasonic cleaning for 15 minutes, and then rinsed with running water until neutral.

[0017] Preferably, the acidic activation uses a mixed acid solution of H2SO4 + HCl, soaked at room temperature for 3 minutes, then soaked with Na2CO3 for 1 minute for neutralization, then rinsed with deionized water, and finally dried with nitrogen.

[0018] Preferably, in the step S2, the protective film is made of polyimide film, with a thickness of 25 μm, a temperature resistance of 300 °C, and the characteristics of acid and alkali corrosion resistance. It is formed by laser cutting and then used for the high-temperature blackening process.

[0019] Preferably, in the step S2, through a vacuum laminator, the film is laminated with a laminating pressure of 0.2 MPa. First, preheat the PI film at 80 °C, cure it at 120 °C for 10 minutes after lamination, use UV glue to fill the film - substrate gap, and perform edge treatment through ultraviolet curing.

[0020] Preferably, in the step S3, an ultraviolet laser is used, and the processing is performed in a point-by-point drilling mode. The key parameters are a power of 8 W, a frequency of 20 kHz, a spot size of 5 μm, a hole diameter of 30 - 50 μm, and an ablation depth of 40 μm.

[0021] Preferably, in the step S4, the blackening solution contains 50 g / L of sodium molybdate, 15 g / L of copper nitrate, 30 mL / L of phosphoric acid, and 0.5 g / L of surfactant, the temperature is controlled at 40 °C, the time is 8 - 12 minutes, and magnetic stirring is used to ensure the exchange of the solution in the pores.

[0022] Preferably, in the step S5, after heating the protective film at 160 °C for 2 minutes, mechanical peeling is carried out. For the residual glue stains, wipe them with acetone. For the photocurable dry film, after soaking it in 3% NaOH solution, ultrasonic cleaning is carried out.

[0023] The beneficial effects of the present invention are as follows:

[0024] 1. By precisely controlling the generation rate and position of the substrate elements, speckles with uniform size can be formed on the sample surface, greatly improving the measurement accuracy and repeatability, and reducing the measurement errors caused by inconsistent speckle sizes.

[0025] 2. By reasonably selecting materials and processes, an obvious gray-scale difference is formed between the speckles and the sample surface, improving the contrast of the speckle pattern and making the image correlation calculation more accurate.

[0026] 3. It can be used to construct an accurate mapping relationship between the physical space and the virtual space. Based on the finite element model, fine mesh division is carried out, and then special speckles are prepared on the surface of the solid specimen, so that the speckle distribution strictly corresponds one-to-one with the finite element grid nodes. This "customized speckle" design breaks through the limitations of traditional random speckles and provides a basis for subsequent data synchronization and model correction. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 It is the flow chart of making DIC speckles for blackening the steel surface of the present invention;

[0028] Figure 2 It is the full flow chart of making DIC speckles for aluminum and its alloys of the present invention;

[0029] Figure 3 It is the flow chart of the research on the digital twin technology based on the fusion of DIC and finite element of the present invention;

[0030] Figure 4 It is the drawing of making DIC speckles based on the finite element grid topology structure of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0031] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0032] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", etc. indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings. It is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and thus cannot be understood as a limitation to the present invention.

[0033] In addition, the terms "first" and "second" are only used for descriptive purposes and cannot be understood as indicating or implying relative importance or implicitly specifying the quantity of the indicated technical features. Thus, the features defined with "first" and "second" may explicitly or implicitly include one or more of the described features. In the description of the present invention, "a plurality" means two or more unless otherwise specifically defined. In addition, the terms "installation", "connection", and "connection" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be directly connected or indirectly connected through an intermediate medium, and it can be the communication inside two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific situations.

[0034] Referring to Figures 1-4 , a method for fabricating DIC speckles in-situ on a substrate at high temperature, comprising:

[0035] Surface pretreatment of the material: Pretreat the surface of the material to be processed, including alkaline degreasing and pickling activation of the surface, to remove the surface of the material's ambient-temperature oxide layer.

[0036] Selection and lamination of the protective film: Select a suitable surface protective film and laminate it. For example, use a polyesterimide film to preheat and laminate at 80 degrees, and use UV glue for edge treatment.

[0037] Speckle processing on the protective film: Perform speckle processing on the protective film, precisely control the spot diameter and ablation depth, and avoid damaging the substrate surface.

[0038] Blackening treatment to generate speckles: After the speckle processing is completed, select a suitable blackening solution and stir it within the range of 35 - 40 °C to promote the exchange of the solution in the holes, so that the substrate at the laser - processed holes completely generates DIC speckles.

[0039] Removal of the protective film and post - treatment: Remove the protective film and carry out post - treatment. For example, the PI film can be mechanically peeled after heating at 160 °C for 2 minutes, then soaked in a chromate passivation solution at room temperature for one minute for sealing treatment, and finally a fluorocarbon resin protective coating is sprayed.

[0040] Detailed process flow and parameters (taking the blackening of the steel surface to make DIC speckles as an example)

[0041] Surface pretreatment

[0042] Alkaline degreasing: Use a solution of NaOH (8% concentration) + surfactant (OP - 10, 0.5% concentration), at a temperature of 70 ± 5 °C, carry out ultrasonic cleaning (40 kHz) for 15 minutes, and then rinse with running water until neutral (conductivity ≤ 50 μS / cm).

[0043] Acid activation: Immerse in a mixed acid solution of H2SO4 (15% concentration) + HCl (5% concentration) at room temperature (25 °C) for 3 minutes, then soak in Na2CO3 (3% concentration) for 1 minute for neutralization, then rinse with deionized water, and finally dry with nitrogen.

[0044] Surface protective film covering

[0045] Selection of the protective film: Select a polyimide (PI) film with a thickness of 25 μm, a heat resistance of 300 °C, which has the characteristics of acid - alkali corrosion resistance, and needs to be laser - cut into shape, suitable for high - temperature blackening process.

[0046] Film - sticking process: Through a vacuum laminator, carry out film - sticking with a laminating pressure of 0.2 MPa. First, pre - heat the PI film at 80 °C, and cure it at 120 °C for 10 minutes after laminating. Use UV glue to fill the film - substrate gap and carry out edge treatment through ultraviolet curing (365 nm, 100 mW / cm 2 , 20 s).

[0047] Laser processing of a speckle hole array on the protective film

[0048] Laser parameters: Use an ultraviolet laser (wavelength 355 nm, pulse width 15 ns), and carry out processing in a point - by - point drilling (non - ablation cutting) processing mode. The key parameters are power 8 W, frequency 20 kHz, spot size 10 μm, hole diameter 30 - 50 μm, and ablation depth 40 μm.

[0049] Aperture array design: Matlab was used to generate a Poisson disk distribution array (minimum spacing = 2 times the aperture), and the density was increased by 20% in the boundary area (to compensate for the imaging edge effect).

[0050] Blackening treatment with film

[0051] Blackening liquid formula: contains sodium molybdate (Na2MoO4) 50g / L (as an oxidation promoter to increase the blackening speed), copper nitrate (Cu(NO3)2) 15g / L (catalyzes the conversion of Fe→Fe3O4), phosphoric acid (H3PO4) 30mL / L (to adjust pH and control reaction rate) and surfactant 0.5g / L (to improve the wettability of the blackening liquid and fill micropores).

[0052] Process conditions: the temperature is controlled at 40°C (temperature control accuracy ±1°C), the time is 8-12 minutes (when the membrane thickness is 25μm, the blackening solution penetration time needs to be ≥5 minutes), and magnetic stirring (200rpm) is used to ensure the exchange of solutions in the pores.

[0053] Protective film removal and post-processing

[0054] Film removal method: For PI film, mechanical peeling can be performed after heating at 160°C for 2 minutes. For residual glue stains, wipe with acetone. For photocured dry film, soak it in 3% NaOH solution and then perform ultrasonic cleaning (40kHz, 5 minutes).

[0055] Surface enhancement: sealing treatment, using chromate passivation solution (CrO32g / L+H3PO41mL / L), soaking at room temperature for 1 minute and then drying. Then spray fluorocarbon resin protective coating (thickness 5μm, 180℃ curing for 15 minutes).

[0056] Detailed process flow and parameters (taking DIC speckle production of aluminum alloy as an example)

[0057] Aluminum substrate pretreatment

[0058] Degreasing cleaning: Use alkaline cleaning solution (NaOH 50g / L + Na3PO4 30g / L), treat at 60±5℃ for 5-8 minutes, and the ultrasonic frequency is 40kHz.

[0059] Mechanical grinding: Grind in the order of sandpaper 400#→800#→1200#, with a grinding angle of 45° cross grain, and control the surface roughness at Ra0.8-1.6μm.

[0060] Acid pickling activation: Use a mixed acid solution (HNO3 (15%) + HF (2%) + H2O) to treat at room temperature for 30-45 seconds, and then soak in Na2CO3 5% solution for 2 minutes for neutralization.

[0061] Surface protective film covering

[0062] Selection of protective film: Polyester (PET) film is selected, with a thickness of 50μm, heat resistance of 150℃, light transmittance > 90%, capable of laser direct writing, and suitable for conventional blackening process.

[0063] Film laminating process: Lamination is carried out through a vacuum laminating machine (pressure 0.15MPa, temperature 90℃) and cured for 5 minutes under hot air circulation at 120℃. Epoxy resin glue (type E - 44) is used for dot - coating edge sealing and cured at 80℃ for 20 minutes.

[0064] Laser processing of speckle hole arrays on the protective film

[0065] Laser parameters: A green laser (wavelength 532nm, pulse width 10ns) is used, and the processing mode is galvanometer scanning (filling density adjustable). The key parameters are power 5W, frequency 50kHz, spot size 5μm, aperture 30 - 50μm, and ablation depth 50μm.

[0066] Hole array optimization: The Fermat spiral distribution algorithm is adopted (to avoid periodic moiré patterns), and the aperture gradient is that the aperture in the central region is 50μm and gradually tapers to 30μm towards the edge (to compensate for imaging distortion).

[0067] Blackening treatment with the film on

[0068] Formula of environment - friendly blackening solution: It contains ammonium molybdate ((NH4)2MoO4) 30g / L (as the main oxidation salt to form a black MoO2 composite film), nickel sulfate (NiSO4) 8g / L (for catalytic oxidation to improve the compactness of the film layer), citric acid (C6H8O7) 10g / L (as a complexing agent to control the reaction rate), and ammonia water is used to adjust the pH to 4.5 - 5.0 to maintain the solution stability.

[0069] Process conditions: The temperature is controlled at 35 ± 1℃, and the time is 15 minutes. Air bubbling (flow rate 0.5L / min) is used for stirring to promote the solution exchange in the holes. The post - treatment is to rinse with deionized water and then dry at 80℃ for 10 minutes.

[0070] Removal of the protective film and post - treatment

[0071] Film removal method: For PET film, mechanical peeling is adopted. For the residual glue layer, it is wiped with ethyl acetate. For photosensitive dry film, it is soaked in 3% KOH solution and then ultrasonically cleaned with deionized water.

[0072] Surface strengthening: Sealing treatment is carried out. Boiling water sealing (95℃, 30 minutes) is adopted to form a dense AlO(OH) layer. Then a perfluorosilane hydrophobic coating (thickness 100nm, cured at 150℃ for 10 minutes) is sprayed.

[0073] Key process control points

[0074] Laser - blackening synergy: When using a 25 - μm - thick PI film, the laser energy density needs to be controlled at 2.5 J / cm 2 , ensuring that the hole depth penetrates the protective film without damaging the substrate; controlling the viscosity of the blackening solution ≤ 30 cP to ensure sufficient capillary action to fill the micropores.

[0075] Blackening uniformity: Add 0.1% BTA (benzotriazole) to inhibit excessive edge oxidation, and monitor the oxidation - reduction potential in real - time (ORP maintained at - 200 to - 150 mV) to ensure uniform blackening. For aluminum alloy materials, when the PET film thickness is 50 μm, the laser energy density needs to be controlled at 1.8 - 2.2 J / cm 2 (to prevent breakdown of the aluminum alloy), and monitor the bottom hole morphology in real - time (online detection using a confocal microscope); add 0.05% sodium benzoate as a corrosion inhibitor, and replenish 5 g / L of ammonium molybdate for each batch to maintain the concentration of the blackening solution and ensure the stability of the blackening solution.

[0076] Example of making DIC speckles on the blackened steel surface

[0077] Preparation work: Prepare the steel material to be processed, and configure the required solutions such as alkaline degreasing solution, acidic activation solution, blackening solution, etc. according to the above - mentioned surface pretreatment steps. Prepare materials such as polyimide (PI) film, UV glue, chromate passivation solution, fluorocarbon resin, etc., as well as equipment such as ultrasonic cleaning equipment, vacuum laminator, ultraviolet laser, magnetic stirrer, etc.

[0078] Surface pretreatment: Put the steel material into the alkaline degreasing solution, and use 40 - kHz ultrasonic cleaning for 15 minutes at 70 °C, then rinse with running water until neutral. Then put the material into the acidic activation solution, soak it at room temperature for 3 minutes, neutralize it with Na2CO3 solution for 1 minute, rinse with deionized water and dry it with nitrogen.

[0079] Covering the surface protective film: Preheat a 25 - μm - thick polyimide (PI) film at 80 °C, and laminate it on the surface of the steel material with a pressure of 0.2 MPa through a vacuum laminator, and then cure it at 120 °C for 10 minutes. Use UV glue to fill the film - substrate gap, and cure it for 20 seconds under ultraviolet light at 365 nm and 100 mW / cm 2 for edge treatment.

[0080] Laser processing of speckle hole arrays on the protective film: Turn on the ultraviolet laser, set the power to 8 W, the frequency to 20 kHz, the spot size to 5 μm, and drill holes point by point on the protective film according to the Poisson disk distribution lattice generated by Matlab. Control the hole diameter to be 30 - 50 μm and the ablation depth to be 40 μm, with the density in the boundary area increased by 20%.

[0081] Film blackening treatment: Put the material with processed speckle hole arrays into the blackening solution, stir it at a speed of 200 rpm for 8 - 12 minutes at a temperature of 40 °C using a magnetic stirrer to ensure that the blackening solution fully penetrates and generates DIC speckles on the substrate at the laser - processed holes.

[0082] Removal of the protective film and post - treatment: Heat the material at 160 °C for 2 minutes, mechanically peel off the PI film, and wipe the residual glue stains with acetone. Then put the material into the chromate passivation solution, soak it at room temperature for 1 minute and then dry it. Finally, spray a fluorocarbon resin protective coating and cure it at 180 °C for 15 minutes.

[0083] Example of fabricating DIC speckles on aluminum alloy materials

[0084] Preparation work: Prepare the aluminum alloy material to be processed, configure the required solutions such as degreasing and cleaning solution, mixed acid solution, and environment - friendly blackening solution, prepare materials such as polyester (PET) film, epoxy resin glue, perfluorosilane, as well as a vacuum laminating machine, green laser, air bubbling equipment, etc.

[0085] Pretreatment of the aluminum substrate: Put the aluminum alloy material into the alkaline degreasing and cleaning solution, process it at a temperature of 60 °C for 6 minutes, and assist the cleaning with 40 kHz ultrasonic waves. Then perform mechanical grinding in the order of sandpaper 400# → 800# → 1200#, with a grinding angle of 45° cross - grain, controlling the surface roughness to be about Ra1.2 μm. Then put the material into the mixed acid solution, process it at room temperature for 40 seconds, and then neutralize it with Na2CO3 solution for 2 minutes.

[0086] Covering the surface protective film: Attach the 50 - μm - thick polyester (PET) film to the surface of the aluminum alloy material through a vacuum laminating machine at a pressure of 0.15 MPa and a temperature of 90 °C, and then cure it for 5 minutes under a hot - air circulation at 120 °C. Use epoxy resin glue for dot - coating edge sealing and cure it at 80 °C for 20 minutes.

[0087] Laser processing of speckle hole arrays on the protective film: Turn on the green laser, set the power to 5 W, the frequency to 50 kHz, the spot size to 5 μm, and perform galvanometer scanning processing of the speckle hole array on the protective film according to the Fermat spiral distribution algorithm. Control the hole diameter to gradually shrink from 50 μm in the central area to 30 μm at the edge, and the ablation depth to be 50 μm.

[0088] Film blackening treatment: Put the material with processed speckle hole arrays into an environmentally friendly blackening solution, stir it at 35 °C for 15 minutes by air bubbling (flow rate 0.5 L / min), then rinse it with deionized water and dry it at 80 °C for 10 minutes.

[0089] Protective film removal and post-treatment: Mechanically peel off the PET film and wipe the residual adhesive layer with ethyl acetate. Put the material into boiling water for sealing treatment for 30 minutes, then spray a perfluorosilane hydrophobic coating and cure it at 150 °C for 10 minutes.

[0090] The above are only the preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. A method for fabricating DIC speckles by in-situ generation on a substrate at high temperature, characterized in that, It includes the following steps: S1. Pretreatment of the material surface: Pretreat the surface of the material to be processed, including surface alkaline degreasing and pickling activation, to remove the surface of the material's ambient-temperature oxide layer; S2. Selection and lamination of the protective film: Select the surface protective film and perform film lamination; S3. Speckle processing on the protective film: Perform speckle processing on the protective film, precisely control the spot diameter and ablation depth, and avoid damaging the substrate surface; S4. Blackening treatment to generate speckles: After the speckle processing is completed, select the blackening solution, stir within the range of 35 - 40 °C to promote the solution exchange in the holes, and enable the substrate at the laser-processed holes to completely generate DIC speckles; S5. Removal of the protective film and post-treatment: Remove the protective film and perform post-treatment.

2. A method for fabricating DIC speckles by in-situ generating on a substrate at high temperature according to claim 1, characterized in that, In the step S1, the pretreatment of the material surface includes alkaline degreasing and acidic activation. The alkaline degreasing uses a solution of NaOH + surfactant, at a temperature of 70 ± 5 °C, with ultrasonic cleaning for 15 minutes, and then rinsed with running water until neutral.

3. A method for fabricating DIC speckles by in-situ generating on a substrate at high temperature according to claim 2, wherein The acidic activation uses a mixed acid solution of H2SO4 + HCl, soaked at room temperature for 3 minutes, then soaked with Na2CO3 for 1 minute for neutralization, then rinsed with deionized water, and finally dried with nitrogen.

4. A method for fabricating DIC speckles by in-situ generating on a substrate at high temperature according to claim 1, wherein In the step S2, the protective film is made of polyimide film, with a thickness of 25 μm, a temperature resistance of 300 °C, and the characteristics of acid and alkali corrosion resistance. It is formed by laser cutting and then used for the high-temperature blackening process.

5. A method for fabricating DIC speckles by in-situ generation on a substrate at high temperature according to claim 4, characterized in that, In the step S2, through a vacuum laminator, film lamination is carried out at a lamination pressure of 0.2 MPa. First, preheat the PI film at 80 °C, cure it at 120 °C for 10 minutes after lamination, use UV glue to fill the film-substrate gap, and perform edge treatment through ultraviolet curing.

6. A method for fabricating DIC speckles by in-situ generating on a substrate at high temperature according to claim 1, wherein, In the step S3, an ultraviolet laser is used to process in a point-by-point drilling mode. The key parameters are a power of 8 W, a frequency of 20 kHz, a spot size of 5 μm, a hole diameter of 30 - 50 μm, and an ablation depth of 40 μm.

7. A method for fabricating DIC speckles by in-situ generating on a substrate at high temperature according to claim 1, wherein In the step S4, the blackening solution contains 50 g / L of sodium molybdate, 15 g / L of copper nitrate, 30 mL / L of phosphoric acid, and 0.5 g / L of surfactant. The temperature is controlled at 40 °C, and the time is 8 - 12 minutes. Magnetic stirring is used to ensure the solution exchange in the holes.

8. A method for fabricating DIC speckles by in-situ generation on a substrate at high temperature according to claim 1, characterized in that In the step S5, heat the protective film at 160 °C for 2 minutes and then perform mechanical peeling. For the residual glue stains, wipe them with acetone. For the photo-cured dry film, soak it in a 3% NaOH solution and then perform ultrasonic cleaning.

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