Meter-scale large-caliber phosphate laser neodymium glass surface modification method

Abstract

The invention relates to a meter-scale large-caliber phosphate laser neodymium glass surface modification method, which comprises the following steps of: changing the composition of process gas in ion beam polishing equipment and the processing angle of an ion source, adopting argon-oxygen mixed gas as the process gas according to the mixing ratio of 5: 2-5: 4, and adjusting the incident angle of the ion source to 30-45 degrees; and the wettability of the surface of the processed neodymium glass is changed from hydrophobicity to hydrophilicity while the surface quality and the surface shape precision of the element are kept. The method comprises the steps of preparation before machining, surface shape detection, path generation, installation and calibration, vacuumizing, ion beam machining, cooling and deflation, cleaning and detection and the like. The problem that cleaning is difficult due to surface hydrophobicity after traditional ion beam machining is effectively solved, the cleaning efficiency is improved, secondary surface pollution is avoided, and the method is particularly suitable for preparing large-diameter optical elements for high-power laser devices and inertial confinement fusion systems.

Description

Technical Field

[0001] This invention belongs to the field of optical cold processing of large-aperture optical components, specifically relating to a method for modifying the surface of meter-scale large-aperture phosphate laser neodymium glass. This method uses ion beam polishing technology to modify the surface of neodymium glass, changing it from hydrophobic to hydrophilic, while ensuring surface defects and full-spectrum performance. This meets the stringent requirements for optical components in fields such as high-power laser devices and inertial confinement fusion. Background Technology

[0002] With the rapid development of advanced manufacturing technologies and the increasing demands of high-end manufacturing, ion beam processing technology, as a precision machining method, has received widespread attention and application in the field of optical component processing. Neodymium phosphate glass is a laser gain medium material with excellent optical properties. Due to its superior spectral characteristics, small nonlinear coefficient, and large laser gain coefficient, it is widely used in high-power laser devices and inertial confinement fusion. The fabrication technology of neodymium glass has reached a relatively mature stage. Currently, the processing of neodymium glass relies on continuous polishing, but this cannot fully meet the requirements for full-spectral error. Therefore, the application of ion beam processing technology in neodymium glass manufacturing is feasible.

[0003] In high-power laser systems, neodymium glass optical components require excellent optical homogeneity, low defect density, and extremely high surface quality to ensure the quality and performance of the output pulse beam. However, due to the large coefficient of thermal expansion and brittleness of neodymium glass, it is easily affected by thermal effects and mechanical stress during processing, leading to surface defects, processing deformation, and decreased precision. Especially with the increase in optical component size, its aspect ratio (the ratio of component diameter to thickness) increases significantly, further increasing the processing difficulty. High aspect ratio neodymium glass optical components not only place higher demands on surface accuracy but also require strict control over low, medium, and high frequency wavefront errors, surface roughness, and laser damage threshold. Therefore, how to achieve high-precision, low-defect processing of neodymium glass optical components has become a pressing technical challenge in the field of optical manufacturing.

[0004] Ion beam processing, as a non-contact ultra-precision machining technology, utilizes high-energy ion beams to perform atomic-level removal and correction on material surfaces. This effectively avoids stress deformation and thermal effects problems associated with traditional machining, making it particularly suitable for the ultra-precision machining of brittle materials. Ion beam technology can also efficiently optimize the surface accuracy of neodymium glass optical components, thus providing a reliable guarantee for the stable operation of high-power laser devices.

[0005] However, due to the properties of neodymium glass and the special nature of its application environment, ion beam processing still faces many challenges in practical applications. For example, neodymium glass is extremely sensitive to changes in the external environment (such as temperature, vacuum level, ion source sputtering, etc.) during processing, which can easily cause surface micro-deformation and surface quality deterioration. At the same time, the stability of the ion beam processing equipment and the precise control of process parameters also have a significant impact on the final processing quality. In addition, research has found that the wettability of the neodymium glass surface changes drastically after ion beam processing, and its hydrophobicity causes great trouble for subsequent cleaning. Currently, the main method is manual wiping, using damping cloth or cotton dipped in a small amount of polishing powder to treat the surface of neodymium glass after ion beam processing. However, this method is prone to leaving polishing liquid residue, resulting in corrosion marks or haze, which greatly affects the surface finish of the neodymium glass components.

[0006] This invention utilizes a specific ratio of argon-oxygen mixed working gas during ion beam polishing. This effectively neutralizes the large number of positive ions accumulated on the surface of neodymium glass elements after ion beam processing, thereby modifying the surface of the neodymium glass elements to be hydrophilic. This reduces the need for subsequent processing steps and prevents re-contamination of the surface. Furthermore, tilting the ion source at a certain angle effectively increases material removal efficiency and improves processing accuracy. Summary of the Invention

[0007] To overcome the shortcomings of the existing technology, a method for modifying the surface of meter-scale large-diameter phosphate laser neodymium glass is provided. By adjusting the gas composition (argon-oxygen mixture) and the incident angle of the ion source in the ion beam polishing process, the surface of neodymium glass is changed from hydrophobic to hydrophilic. This solves the problem of difficult cleaning caused by the hydrophobicity of the neodymium glass surface after traditional ion beam processing, avoids polishing fluid residue and surface contamination caused by manual wiping, and improves the efficiency and quality of subsequent cleaning.

[0008] The technical solution of the present invention is as follows:

[0009] A method for surface modification of meter-scale large-diameter phosphate laser-modified neodymium glass, characterized by the following steps:

[0010] S1. Preparation: Design a non-metallic protective structure based on the dimensions of the neodymium glass component to be processed, so that the processing area is exposed and the non-processing area is covered;

[0011] S2. Surface shape inspection: The surface shape data of the neodymium glass component to be processed is obtained by optical interferometry inspection method;

[0012] S3. Processing path planning: Based on the surface shape data, generate the ion beam removal function and calculate the residence time distribution;

[0013] S4. Clamping and positioning: Fix the neodymium glass element to be processed in the vacuum chamber of the ion beam processing equipment and perform spatial positioning;

[0014] S5. Vacuum environment establishment: After evacuating to the working pressure, a mixture of argon and oxygen in a ratio of 5:2 to 5:4 is introduced to neutralize the positive ions on the surface and achieve hydrophilic modification.

[0015] S6. Ion beam processing: The ion source is controlled to shape the surface of the neodymium glass element to be processed at an incident angle of 30° to 45°, while maintaining the flow rate of the mixed gas;

[0016] S7. Post-processing: After processing, the vacuum chamber and neodymium glass workpiece are cooled. During the cooling process, the ratio of argon to oxygen mixture is maintained. The workpiece is removed after the vacuum chamber returns to normal temperature and pressure.

[0017] S8. Cleaning and Inspection: Clean the processed workpiece and inspect its surface properties.

[0018] Furthermore, the non-metallic protective structure includes a quartz glass frame, a ceramic clamp, or a polymer protective cover.

[0019] Furthermore, the optical interference detection method includes using a laser interferometer with wavelengths in the visible or near-infrared bands.

[0020] Furthermore, the working air pressure is 10. -4 -10 -2 Pa.

[0021] Furthermore, the cooling process is carried out under the condition of continuous introduction of process gas, and the cooling time is not less than 1 hour.

[0022] Furthermore, the cleaning process includes cleaning using a polar solvent.

[0023] Furthermore, the polar solvent includes deionized water, alcohol, or a mixture thereof.

[0024] Furthermore, the surface performance testing includes surface roughness, surface shape accuracy, and contact angle measurement.

[0025] Compared with the prior art, the technical effects of the present invention are as follows:

[0026] By introducing a certain proportion of argon-oxygen mixed working gas during ion beam polishing and adjusting the incident angle of the ion source to perform ion beam shaping on the surface of neodymium glass components, the surface wettability of neodymium glass components after processing can be effectively improved, while ensuring high processing and shaping efficiency. This plays an important role in the surface processing quality and post-processing of neodymium glass components. Attached Figure Description

[0027] Figure 1 This is a flowchart of the method for surface modification of meter-scale large-diameter phosphate laser neodymium glass according to the present invention;

[0028] Figure 2 This is a schematic diagram of the ignition processing stage in this invention.

[0029] Figure 3 The figures show the comparison of the PV and GRMS1 indices of neodymium glass elements before and after ion beam processing in this invention. (a) Transmission PV before processing (b) GRMS1 before processing (c) Transmission PV after processing (d) GRMS1 after processing.

[0030] Figure 4 This is a comparison of the hydrophobicity and hydrophilicity of the surface of neodymium glass elements before and after ion beam modification in this invention, wherein (a) the surface hydrophobicity after argon processing and (b) the surface hydrophilicity after argon-oxygen mixed gas processing. Detailed Implementation

[0031] The technical solution of the present invention will be described in detail below with reference to the accompanying drawings and embodiments, but this should not be construed as limiting the scope of protection of the present invention.

[0032] Please see Figure 1 , Figure 1 The flowchart of the method for surface modification of meter-scale large-diameter phosphate laser neodymium glass according to the present invention is shown in the figure. This embodiment of the method for surface modification of meter-scale large-diameter phosphate laser neodymium glass includes:

[0033] Preparation before ion beam processing:

[0034] Component to be processed: Φ800mm×50mm neodymium phosphate glass, initial surface hydrophobic, contact angle approximately 90°.

[0035] The neodymium glass is fixed to the rotary table using ceramic clamps, and a ring frame made of high-purity quartz glass is used to expose only the surface to be processed, preventing the tooling from sputtering and contaminating the metal elements.

[0036] (2) Surface shape inspection: Use a 600mm laser interferometer to perform full-aperture surface shape inspection on the component to be processed at Brewster angle and record its transmission surface shape error.

[0037] (3) Generation of ion beam processing path: Input the above detection data into the processing software of the ion beam polishing equipment, and select the appropriate removal function and the dwell time function required for deterministic shaping processing control;

[0038] (4) Installation and calibration: The component to be processed is installed in the vacuum chamber of the ion beam polishing equipment using a customized tooling fixture, and a dial indicator is installed for mechanical positioning. Finally, the glass frame is installed and fixed, and its position is adjusted to ensure that the working surface of the component is exposed and the metal tooling is covered.

[0039] (5) Vacuuming and ignition processing: Start the equipment to begin vacuuming, so that the vacuum degree of the ion beam polishing equipment vacuum chamber is lower than 10-3. Introduce argon-oxygen mixture, wait for more than 10 minutes, turn on the ion source communicator, continue to wait for more than 10 minutes, and then turn on the ion source. After the ion source ignites, wait for more than 5 minutes.

[0040] (6) Ignition Processing: After the ion source has ignited and stabilized, process gas is introduced. The process gas is a mixture of argon and oxygen in a ratio of 5:2 to 5:4. The ion source angle is adjusted to 30° to 45°. After the operation is completed, surface treatment processing of the neodymium glass element begins. During the processing, the machine tool operation status and the stability of the ion source should be observed regularly.

[0041] (7) Cooling and venting: After the component is processed, maintain the flow rate of argon-oxygen mixture and cool for more than 2 hours. After cooling, vent the gas and wait for the hatch to open before removing the component.

[0042] (8) Cleaning and testing: The processed components were cleaned with deionized water and alcohol. After cleaning, the surface finish and surface shape were tested. The PV value of the neodymium glass components decreased from 0.3561λ before processing to 0.23083λ, and the GRMS1 index decreased from 10.12766nm / cm before processing to 6.54476nm / cm, which met the technical requirements. The surface hydrophilicity of the neodymium glass components decreased from 77° after processing with argon gas alone to about 30° after processing with argon-oxygen mixed gas, which greatly improved the hydrophilicity of the neodymium glass components after ion beam modification.

[0043] This invention, while ensuring the surface finish and shape accuracy of neodymium glass components, transforms the hydrophobicity of the processed neodymium glass surface into hydrophilicity by altering the ratio of the argon-oxygen mixture in the process gas and the incident angle of the ion source, greatly facilitating subsequent cleaning and inspection. It not only enables rapid reshaping of large-diameter neodymium glass but also maintains post-processing hydrophilicity while preserving its surface finish, thus simplifying subsequent cleaning of the neodymium glass.

Claims

1. A method for surface modification of meter-scale large-diameter phosphate laser-modified neodymium glass, characterized in that, Includes the following steps: S1. Preparation: Design a non-metallic protective structure based on the dimensions of the neodymium glass component to be processed, so that the processing area is exposed and the non-processing area is covered; S2. Surface shape inspection: The surface shape data of the neodymium glass component to be processed is obtained by optical interferometry inspection method; S3. Processing path planning: Based on the surface shape data, generate the ion beam removal function and calculate the residence time distribution; S4. Clamping and positioning: Fix the neodymium glass element to be processed in the vacuum chamber of the ion beam processing equipment and perform spatial positioning; S5. Vacuum environment establishment: After evacuating to the working pressure, a mixture of argon and oxygen in a ratio of 5:2 to 5:4 is introduced to neutralize the positive ions on the surface and achieve hydrophilic modification. S6. Ion beam processing: The ion source is controlled to shape the surface of the neodymium glass element to be processed at an incident angle of 30° to 45°, while maintaining the flow rate of the mixed gas; S7. Post-processing: After processing, the vacuum chamber and neodymium glass workpiece are cooled. During the cooling process, the ratio of argon to oxygen mixture is maintained. The workpiece is removed after the vacuum chamber returns to normal temperature and pressure. S8. Cleaning and Inspection: Clean the processed workpiece and inspect its surface properties.

2. The method for surface modification of meter-scale large-diameter phosphate laser-modified neodymium glass according to claim 1, characterized in that, The non-metallic protective structure includes a quartz glass frame, ceramic clamps, or a polymer protective cover.

3. The method for surface modification of meter-scale large-diameter phosphate laser-modified neodymium glass according to claim 1, characterized in that, The optical interference detection method includes using a laser interferometer with wavelengths in the visible or near-infrared bands.

4. The method for surface modification of meter-scale large-diameter phosphate laser-modified neodymium glass according to claim 1, characterized in that, The working air pressure is 10. -4 -10 -2 Pa.

5. The method for surface modification of meter-scale large-diameter phosphate laser-modified neodymium glass according to claim 1, characterized in that, The cooling process is carried out under the condition of continuous introduction of process gas, and the cooling time is not less than 1 hour.

6. The method for surface modification of meter-scale large-diameter phosphate laser-modified neodymium glass according to claim 1, characterized in that, The cleaning process includes cleaning with a polar solvent.

7. The method for surface modification of meter-scale large-diameter phosphate laser-modified neodymium glass according to claim 6, characterized in that, The polar solvent includes deionized water, alcohol, or a mixture thereof.

8. The method for surface modification of meter-scale large-diameter phosphate laser-modified neodymium glass according to claim 1, characterized in that, The surface performance testing includes surface roughness, surface shape accuracy, and contact angle measurement.

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