A method for measuring parameters of pulsed laser based on titanium nanometer film

Abstract

This invention provides a method for measuring pulsed laser parameters based on titanium nanofilms, belonging to the field of pulsed laser parameter measurement methods. The method first prepares titanium nanoparticle ink; then, a titanium deposition layer is prepared by inkjet printing or spin coating; finally, the titanium deposition layer is placed within the laser scanning range, a single-point or line scanning mode is set, and images of the sintered titanium region are recorded. The corresponding laser parameters are obtained through image processing software analysis. This method can intuitively, conveniently, and cost-effectively obtain key pulsed laser parameters, and can accurately obtain parameters such as spot size and repetition frequency.

Description

Technical Field

[0001] This invention belongs to the field of pulsed laser parameter measurement methods, specifically relating to a pulsed laser parameter measurement method based on titanium nanofilm. Background Technology

[0002] Due to their advantages such as strong directionality, high brightness, monochromaticity, and good coherence, lasers have been widely used in modern industry, national defense, and medicine. Based on their operating state, lasers can be divided into two categories: continuous light and pulsed light. Among them, pulsed light, with its higher peak power, more controllable parameters, and unique electrical effects, has received more extensive research and application. In various research and applications, there are high requirements for important laser parameters, such as power, spot diameter, pulse width, divergence angle, and spot drift; therefore, the measurement technology of pulsed laser parameters is of great research value.

[0003] Currently, the main methods for measuring pulsed laser parameters include scanning, array detection, and imaging. These methods all require purchasing specific sensors for different wavelengths and frequencies of laser light, and to ensure sensor lifespan and accuracy, frequency conversion and attenuation optical paths need to be constructed. These methods suffer from high costs, complex processes, and small window sizes. However, in the widespread industrial applications of lasers, there is a need for laser measurement methods that are simpler, less expensive, and can achieve higher power and a wider frequency range. Summary of the Invention

[0004] The purpose of this invention is to solve the problems of high cost, complicated process and small window of existing pulsed laser parameter measurement methods, and to provide a pulsed laser parameter measurement method based on titanium nanofilm.

[0005] This invention provides a method for measuring pulsed laser parameters based on titanium nanofilms, comprising:

[0006] Step 1: Preparation of titanium nanoparticle ink;

[0007] Step 2: Prepare a titanium deposition layer by inkjet printing or spin coating;

[0008] Step 3: Place the titanium deposition layer within the laser scanning range, set the single-point or line scanning mode, record the image of the titanium sintering area after sintering, and obtain the corresponding laser parameters through image processing software analysis.

[0009] Preferably, step one specifically involves: dispersing titanium nanoparticles in an organic solvent to obtain ink, then ultrasonically dispersing the ink at a power of 120-200W for 2-4 hours, filtering the ink, and obtaining titanium nanoparticle ink.

[0010] Preferably, the organic solvent is ethylene glycol or isopropanol.

[0011] Preferably, the mass fraction of the titanium nanoparticles is 4-6%.

[0012] Preferably, the filtration is performed using a 0.45μm PTFE filter membrane.

[0013] Preferably, the inkjet printing parameters in step two are set as follows: dot pitch 0.04×0.04-0.045×0.045mm, printing speed 10-40mm / s, and printing temperature 120-140℃.

[0014] Preferably, in the inkjet printing process, the substrate is a ceramic substrate.

[0015] Preferably, the ceramic substrate is made of alumina or zirconium oxide.

[0016] Beneficial effects of the present invention

[0017] This invention provides a method for measuring pulsed laser parameters based on titanium nanofilms. The method involves preparing a titanium nanoparticle deposition layer using inkjet printing, followed by sintering the titanium deposition layer with the test beam, causing discoloration in the sintered titanium region. Parameters such as laser power, spot diameter, pulse width, and scan line spacing are determined by measuring the color, size, and adjacent distances of the discolored region. Due to the relatively low density of the deposited nanoparticles (air between particles), the deposition layer has high thermal resistance and clear sintering boundaries. Furthermore, because the composition of the titanium nanoparticles changes significantly during sintering, different sintering degrees result in distinct color differences, allowing for a large reference color gamut. Therefore, the measurement results are essentially the same as those obtained using imaging methods. This invention provides a direct, convenient, and low-cost way to obtain key pulsed laser parameters, and can accurately obtain parameters such as spot size and repetition frequency. Additionally, this invention can expand the range of laser pulse frequency measurement by controlling parameters such as laser scanning speed. Attached Figure Description

[0018] Figure 1 The image shows the sintering effect at different laser powers in Example 1.

[0019] Figure 2 This is a sintering effect diagram under the circuit scanning condition of Example 1;

[0020] Figure 3 This is a comparison diagram of the spot diameters of the titanium thin film method and the laser profilometer measurement method in Example 3;

[0021] Figure 4 This is a comparison chart of the spot diameter under the D4σ standard after the correction (×1.135) in Example 3. Detailed Implementation

[0022] This invention provides a method for measuring pulsed laser parameters based on titanium nanofilms, comprising:

[0023] Step 1: Preparation of titanium nanoparticle ink; specifically, preferably: dispersing titanium nanoparticles in an organic solvent, preferably ethylene glycol or isopropanol, wherein the mass fraction of titanium nanoparticles is preferably 4-6%, to obtain ink, and then ultrasonically dispersing at a power of 120-200W for 2-4 hours, preferably using a 0.45μm PTFE filter membrane, to obtain titanium nanoparticle ink. The present invention obtains titanium ink with better dispersibility and stability through the above preparation method, reducing the impact of nanoparticle agglomeration and sedimentation on the uniformity of the deposition layer during inkjet printing;

[0024] Step 2: Prepare a titanium deposition layer by inkjet printing or spin coating. The preferred inkjet printing parameters are: dot pitch of 0.04×0.04-0.045×0.045 mm, printing speed of 10-40 mm / s, and printing temperature of 120-140℃. The substrate used during printing is preferably a ceramic substrate, and the preferred material for the ceramic substrate is alumina or zirconium oxide. A highly uniform titanium nanoparticle deposition layer with controllable thickness is obtained through the above inkjet printing or spin coating. The number of printing layers is single, and the shape and size can be selected according to actual testing requirements.

[0025] Step 3: Place the titanium deposition layer within the laser scanning range, set the single-point or line scanning mode, record the image of the titanium sintering area after sintering, and obtain the corresponding laser parameters through image processing software analysis.

[0026] According to the present invention, the test range of the laser is as follows: for a 1064nm nanosecond pulse, the measurable laser power density (laser power / spot area) ranges from 50 to 1000 W / mm². 2 Within the aforementioned laser power density range, the measurement range of the spot diameter is unlimited. The laser power can be deduced from the laser power density and the spot diameter. Since there is a minimum spot diameter (approximately 150 μm), the minimum measurable power is approximately 2 W, and the maximum power is unlimited (adjust the spot size so that its power density is within the measurement range).

[0027] According to this invention, the selection of the scanning mode—whether it is single-point or line scanning—is determined by the measured parameters. Point measurement facilitates the determination of power density, spot diameter, and laser power (point measurement involves single-pulse sintering). The initial measurement parameters are laser power density and spot diameter: the spot diameter can be obtained after software binarization, and the laser power density can be obtained from color number analysis. The laser power can be calculated from the laser power density and spot diameter: Laser power = Power density * Spot area.

[0028] The described line scanning facilitates the determination of scanning parameters such as laser repetition frequency and scan line spacing. When selecting line scanning, the spot diameter needs to be determined through point measurement before choosing a suitable scanning speed for surface measurement (line scanning). The suitable scanning speed mentioned in this invention refers to a speed that allows for a relatively clear distinction between the sintered and unsintered areas. For example, if the spot size is 300 μm and the laser repetition frequency is approximately 10 kHz, then the scanning speed v can be taken as 300 μm * 2 * 10 kHz = 6000 mm / s. In the above formula, 2 represents a 1:1 ratio between the sintered and unsintered areas.

[0029] The image processing software described in this invention uses the commercially available ImageJ software well-known in the art. Alternatively, MATLAB can be used for grayscale binarization processing, but the boundaries of the sintering region need to be clearly defined (by determining a fixed threshold).

[0030] The present invention will now be described in further detail with reference to specific embodiments.

[0031] Example 1

[0032] 1. Disperse titanium nanoparticles with a mass fraction of 5% into ethylene glycol.

[0033] 2. Disperse the ink ultrasonically at 180W power for 2 hours.

[0034] 3. Filter the ink using a 0.45μm PTFE membrane.

[0035] 4. Under printing parameters of 0.04*0.04mm dot spacing, 20mm / s printing speed, and 120℃ printing temperature, a single-layer titanium deposition layer was printed on an alumina ceramic substrate with poor thermal conductivity. The titanium thin film deposition layer was a 5*5mm rectangle (one sintering point was tested within each small rectangle during spot testing).

[0036] 5. First, perform single-pulse sintering at any laser power to obtain a single sintering region. Measure the diameter of this sintering region to obtain the spot diameter (approximately 300 μm). Use laser single-pulse sintering with laser powers of 30 W, 40 W, and 50 W to obtain the sintering state. Figure 1 The image shows the sintering effect under different laser powers in Example 1. In this invention, the spot diameter is directly determined by the sintering area. However, calibration is required before testing the laser power density. That is, it is necessary to first use a laser pulse with known parameters to sinter the titanium nanofilm and give the correspondence between color and laser power density. For example, in Example 1, the sintering color under three different laser power densities is given: 30W (424.4W / mm2); 40W (565.9W / mm2); and 50W (707.4W / mm2). Figure 1 This indicates that the sintered bodies on titanium thin films exhibit significant color differences under different laser power densities, which facilitates the determination of laser power density.

[0037] 6. Record images of the titanium sintering area after sintering, and analyze the chromaticity of the sintered titanium film at the corresponding power density using image processing software, thus completing the preliminary calibration. Specific parameters are obtained as follows:

[0038] First, the diameter of the light spot is obtained: the image is converted to grayscale using MatLab software, and a grayscale threshold (usually between 80-150, 100 is used in this case) is set for binarization. Finally, the format of white (255) pixels is calculated. Based on the image pixels and the corresponding scale, the diameter of the circle with the same area corresponding to the number of pixels is calculated. This diameter is the measured diameter of the light spot.

[0039] Pulse frequency: The length of L2 is measured by an optical imaging system, and the laser repetition frequency f is calculated according to f = v / L2, where v is the laser scanning speed (known).

[0040] Scan line spacing: The length of L1, measured by an optical imaging system, is the scan line spacing.

[0041] Figure 2 Figure 1 shows the sintering effect under the circuit scanning condition in Example 1. Figure a is an overall schematic diagram, and Figure b is an enlarged view of the area within the box in Figure a. L3 corresponds to the spot diameter, L2 represents the pulse width (f = v / L2, where f is the laser repetition frequency and v is the scanning speed, which is known), and L1 is the scanning line spacing. This figure illustrates the actual result of the surface measurement (circuit scanning), clearly showing a distinct distinction between the sintered and unsintered areas, and enabling high-precision measurement of the laser repetition frequency.

[0042] Example 2

[0043] 1. Disperse 5% titanium nanoparticles in an organic solvent (ethylene glycol or isopropanol).

[0044] 2. Disperse the ink ultrasonically at 180W power for 2 hours.

[0045] 3. Filter the ink using a 0.45μm PTFE membrane.

[0046] 4. Under printing parameters of 0.04*0.04mm dot pitch, 20mm / s printing speed, and 120℃ printing temperature, a single-layer titanium deposition layer was printed on an alumina ceramic substrate with poor thermal conductivity. The titanium thin film deposition layer was a 10*40mm rectangle.

[0047] 5. Spot measurement:

[0048] Spot diameter: The spot diameter was measured by single pulse light. The image was converted to grayscale using MatLab software, and a grayscale threshold (100 was used in this case) was set for binarization. Finally, the white (255) pixel format was calculated. Based on the image pixels and the corresponding scale, the diameter of the circle with the same area corresponding to the number of pixels was calculated to be 170μm.

[0049] Laser power: By comparing the colorimetric values, the laser energy density is determined to be approximately 880W / mm2. Using the laser power density formula P=A*Pd; (P is the laser power, A is the spot area, and Pd is the laser power density), the laser power is calculated to be approximately 20W.

[0050] 6. Under the parameters of 20W laser power and 170μm spot diameter, and a scanning speed of 5000mm / s, surface measurement yields L1 = 199.599μm, meaning the laser scanning line spacing is approximately 200μm. L2 = 102.116μm. From f = v / L2, f = 49.0kHz can be calculated, and the laser repetition frequency is approximately 50kHz. L3 = 168.773μm, where L3 is the spot diameter, which is close to the spot diameter measured in the point measurement (170μm).

[0051] Example 3

[0052] 1. Disperse 5% titanium nanoparticles in an organic solvent (ethylene glycol or isopropanol).

[0053] 2. Disperse the ink ultrasonically at 180W power for 2 hours.

[0054] 3. Filter the ink using a 0.45μm PTFE membrane.

[0055] 4. Under printing parameters of 0.04*0.04mm dot pitch, 20mm / s printing speed, and 120℃ printing temperature, a single-layer titanium deposition layer was printed on an alumina ceramic substrate with poor thermal conductivity. The titanium thin film deposition layer was a 5*5mm rectangle.

[0056] 5. The laser power is fixed at 35W (as long as the laser power density is within the test range). The distance between the convex lens and the substrate is changed to vary the spot size. Single-pulse sintering is performed at different spot sizes, and the diameter of the sintered point is measured to obtain the spot diameter data for the titanium thin film method. Specific data are shown in Table 1. In addition, measurements are taken using a laser profilometer to obtain the baseline test results. A comparison of the two methods shows that the titanium thin film method has superior test accuracy. Figure 3As shown, the test results are generally smaller than the spot diameter under the D4σ standard. Since there are many definitions of spot diameter, the commonly used standard is the D4σ standard. Although the titanium thin film method cannot perfectly match the spot diameter under the D4σ standard, its overall trend is consistent. To improve its practicality in engineering, a correction factor (original titanium test diameter × 1.135) is proposed. This corrected diameter is closer to the spot diameter under the D4σ standard. After correction (×1.135), a more accurate spot diameter under the D4σ standard can be obtained. Figure 4 As shown.

[0057] Table 1 shows the test results for light spots of different diameters using two different test methods.

[0058]

Claims

1. A method for measuring parameters of a pulsed laser based on a titanium nanofilm, characterized in that, The application relates to a method for preparing a titanium sintering area by laser sintering. Step one: preparing a titanium nanoparticle ink; Step two: preparing a titanium deposition layer by inkjet printing or spin coating; Step three: placing the titanium deposition layer in a laser scanning range, setting a single-point or line scanning mode, recording a titanium sintering area image after sintering, and obtaining corresponding laser parameters by image processing software analysis.

2. The method according to claim 1, wherein the method is a pulsed laser parameter measurement method based on a titanium nanofilm. The step one is specifically as follows: dispersing titanium nanoparticles into an organic solvent to obtain the ink, then ultrasonic dispersing for 2-4 hours under the power of 120-200 W, filtering the ink, and obtaining the titanium nanoparticle ink.

3. The method according to claim 2, wherein the method is a pulsed laser parameter measurement method based on a titanium nanofilm. The organic solvent is ethylene glycol or isopropyl alcohol.

4. The method according to claim 2, wherein the method is a pulsed laser parameter measurement method based on a titanium nanofilm. The mass fraction of the titanium nanoparticles is 4-6%.

5. The method according to claim 2, wherein the method is a pulsed laser parameter measurement method based on a titanium nanofilm. The filtering is performed by using a 0.45-micron PTFE filter membrane.

6. The method of claim 1, wherein the method is a pulsed laser parameter measurement method based on a titanium nanofilm. In the step two, the inkjet printing parameters are set as follows: printing point spacing 0.04*0.04-0.045*0.045 mm, printing speed 10-40 mm / s, and printing temperature 120-140 DEG C.

7. The method according to claim 1, wherein the method is a pulsed laser parameter measurement method based on a titanium nanofilm. In the inkjet printing, the substrate is a ceramic substrate.

8. The method according to claim 7, wherein the method is a pulsed laser parameter measurement method based on a titanium nanofilm. The material of the ceramic substrate is alumina or zirconia.

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