A laser processing method for improving the surface roughness of diamond
By using alternating path scanning of a preheated diamond sheet with a blue laser and an ultrashort pulse laser, the problems of schlieren and cracking caused by thermal stress concentration in laser polishing were solved, achieving uniform improvement in diamond surface roughness and increased efficiency.
Patent Information
- Application Number
- CN202311488782.3
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- Filing Date
- 2023-11-09
- Publication Date
- 2026-05-15
- Estimated Expiration
- 2043-11-09
AI Technical Summary
Existing laser polishing methods tend to cause thermal stress concentration on diamond surfaces, resulting in streaks and cracks, and cannot effectively reduce roughness.
A blue laser with a preheated diamond sheet is used, combined with an ultrashort pulse laser to scan and ablate along a large-spacing alternating path. The four-step scanning path avoids thermal stress concentration and reduces local temperature gradient.
It effectively improves the surface roughness of diamond, prevents cracking, and enhances surface uniformity and ablation efficiency.
Smart Images
Figure CN117259992B_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of diamond processing technology, and in particular to a laser processing method for improving the surface roughness of diamond. Background Technology
[0002] Existing diamond surface treatment methods mainly employ mechanical polishing, chemical polishing, electrical discharge polishing, ion beam polishing, and laser polishing. Laser polishing is a non-contact polishing method that uses no mechanical force, making the diamond sheet less prone to breakage. However, during existing laser polishing processes, the concentrated laser beam over a short period can cause thermal stress concentration on the diamond surface, leading to deep grooves and a textured effect. This textured effect prevents effective reduction of surface roughness, and the resulting localized thermal stress concentration can cause thinner diamond sheets to crack. Summary of the Invention
[0003] To address the problems mentioned above, this application provides a laser processing method for improving the surface roughness of diamond, which can effectively reduce the fretting caused by thermal stress generated on the diamond surface by laser scanning ablation, thereby improving the processing effect of laser to improve the surface roughness of diamond.
[0004] To achieve the above objectives, the technical solution provided in this application is as follows:
[0005] A laser processing method for improving the surface roughness of diamond includes a laser generator for preheating a diamond sheet, an ultrashort pulse laser generator for ablation of the diamond sheet surface, a scanning galvanometer for adjusting the scanning ablation direction of the ultrashort pulse laser, a collimating focusing lens for concentrating the heated laser beam, and a processing stage assembly for mounting and adjusting the diamond sheet. The processing stage assembly is equipped with a temperature sensor for real-time temperature measurement of the diamond sheet. The processing method includes the following steps:
[0006] S1: After fixing the diamond sheet to be processed on the processing table assembly, adjust the collimating focusing lens to align with the surface of the diamond sheet, and use the laser generator to preheat the surface of the diamond sheet;
[0007] S2: After monitoring that the surface of the diamond sheet reaches the preset temperature, the ultrashort pulse laser generator is activated to emit an ultrashort pulse laser. The scanning galvanometer makes the ultrashort pulse laser maintain the incident angle along the preset path to perform large-spacing alternating laser ablation.
[0008] S3: Maintain a large spacing between each ablation path, and after alternating vertical ablation of the paths, the surface roughness of the diamond sheet reaches the preset value.
[0009] Compared with the prior art, this application achieves the technical effect of reducing local thermal stress concentration on the diamond sheet surface and improving the surface roughness of the diamond sheet by preheating the diamond sheet to prevent large local temperature differences during the ablation of the ultrashort pulse laser, and by using a large-interval scanning ablation along each path and performing alternating path scanning.
[0010] Preferably, the large-spacing alternating laser ablation step in S2 is as follows:
[0011] S100: Laser scanning ablation is performed along the X-axis of the diamond sheet, maintaining a large spacing, to form parallel ablation paths with equal spacing.
[0012] S200: Scan and ablate along the X-axis of the diamond sheet one by one within the spacing formed by the first path to form a second ablation path that is parallel to each other and equally spaced.
[0013] S300: Adjust the incident direction of the scanning galvanometer so that the ultrashort pulse laser maintains a large gap along the Y-axis of the diamond sheet to perform laser scanning ablation, forming parallel and equally spaced ablation paths.
[0014] S400: Scan and ablate along the Y-axis of the diamond sheet one by one within the spacing formed by the path three to form parallel and equally spaced ablation paths four.
[0015] The paths 1, 2, 3, and 4 are perpendicular to each other.
[0016] Based on the above scheme, the large spacing between adjacent ablation operations can reduce thermal stress concentration during each scan ablation. Furthermore, by using alternating scans in the same direction and mutually perpendicular scan paths, the ablation process can cover the entire diamond surface as much as possible, effectively reducing the overall roughness of the diamond sheet and keeping the surface uniform.
[0017] Specifically, the laser generator emits blue light with a wavelength range of 380-500nm. By preheating the diamond sheet with blue light, the surface of the diamond sheet can be preheated uniformly and the temperature increase can be more controllable.
[0018] Furthermore, the laser emitted by the laser used for preheating is a continuous laser with a wavelength range of 400-450nm, while the laser emitted by the ultrashort pulse laser generator used for ablation is a pulsed laser with a wavelength of 532nm.
[0019] Furthermore, the large spacing maintained between adjacent ablation paths is in the range of 25-30 μm.
[0020] Furthermore, the laser generator forms a preheated spot on the surface of the diamond sheet, the diameter of the spot being 1-4 cm and the preheating temperature being 40-100 °C. The spot is continuously heated while the ultrashort pulse laser scans the ablation path, so that the surface temperature of the diamond sheet remains constant.
[0021] Furthermore, the processing table assembly includes a processing table base and a vacuum adsorption fixture disposed on the processing table base. The diamond sheet is placed on the vacuum adsorption fixture for adsorption and fixation. The temperature sensor has a temperature sensor that monitors the surface temperature of the diamond sheet in real time and feeds it back to the laser generator.
[0022] Furthermore, the incident angle of the ultrashort pulse laser scanning and ablation of the diamond sheet surface is 90 degrees.
[0023] Furthermore, the laser beam used for scanning ablation by the ultrashort pulse laser is a single beam, and its scanning feed speed is 0.3-0.5 μm / s.
[0024] Furthermore, the initial roughness of the diamond sheet is 100-700 μm, and the roughness of the diamond sheet after ablation treatment is 0.5-0.9 μm.
[0025] The beneficial effects of this invention are as follows: This invention uses blue light as a preheating light source to form a large-size, low-energy-density light spot on the diamond sheet surface, without damaging the diamond sheet substrate; overall preheating of the diamond sheet avoids large temperature gradients that could cause diamond sheet breakage during ultrashort pulse laser ablation; by setting a large-interval scanning path and using a four-step scanning method, the efficient removal of protruding particles on the diamond surface can be improved; the method of this invention is flexible and fast to operate, and the required control system is simple and reliable, thus improving the ablation efficiency of the product. Attached Figure Description
[0026] Figure 1 This is an overall structural diagram of the laser processing device for diamond surface roughness in an embodiment of the present invention;
[0027] Figure 2 This is a schematic diagram of the path scanning of the ultrashort pulse laser in an embodiment of the present invention;
[0028] Figure 3 This is a schematic diagram of scanning path one and path two in an embodiment of the present invention;
[0029] Figure 4 This is a schematic diagram of scanning path three and path four in an embodiment of the present invention.
[0030] In the diagram, 1-laser generator, 2-ultrashort pulse laser generator, 201-ultrashort pulse laser, 3-collimating focusing lens, 4-scanning galvanometer, 401-X-axis polarizer, 402-Y-axis polarizer, 403-objective lens, 5-processing stage base, 6-temperature sensor, 7-vacuum adsorption fixture, and 8-diamond sheet. Detailed Implementation
[0031] The technical solutions of this invention will now be clearly and completely described with reference to the accompanying drawings. The components of the invention described and shown in the drawings herein can typically be arranged and designed in various different configurations. Therefore, the following detailed description of the invention provided in the drawings is not intended to limit the scope of the claimed invention, but merely to illustrate selected embodiments of the invention. All other embodiments obtained by those skilled in the art based on the embodiments of the invention without inventive effort are within the scope of protection of this invention.
[0032] Example
[0033] Traditional mechanical polishing methods often retain significant roughness, resulting in noticeable bumps. In existing laser-assisted diamond sheet polishing processes, the thin diamond sheet is prone to thermal stress concentration during laser ablation, leading to breakage. To address these issues, this invention proposes a laser processing method to improve the surface roughness of diamond. Please refer to [link to relevant documentation]. Figure 1 The overall structural diagram of the laser processing apparatus is shown. The apparatus required by this invention application includes a laser generator 1 for emitting blue light with a wavelength range of 400-450nm, used to preheat the surface of a diamond sheet 8. A collimating focusing lens 3 is connected to its front end. The diamond sheet 8 is fixedly mounted on the processing table base 5 by a vacuum adsorption clamp 7. The collimating focusing lens 3 forms a large-size, low-energy-density light spot on the surface of the diamond sheet 8 with the emitted blue light. The diameter of the light spot ranges from 1-4cm, and the size of the light spot is determined by the area to be processed. The size of the diamond sheet 8 is determined by the amount of light spot that completely covers the upper surface of the diamond sheet 8 for preheating. When the surface of the diamond sheet 8 is heated to 40-100℃, preferably 100℃, the output power of the blue light is maintained to keep the surface of the diamond sheet 8 constant. The surface temperature of the diamond sheet 8 is measured using a thermometer 6 with a temperature sensor. The thermometer 6 is connected to the controller of the laser generator 1 for temperature feedback. The thermometer 6 can be set at the bottom of the diamond sheet 8 or at a distance from the diamond sheet 8.
[0034] Please see Figure 2The diagram illustrates the path scanning of an ultrashort pulse laser. After the temperature sensor 6 measures the surface temperature of the diamond sheet 2 and heats it to a preset temperature, the ultrashort pulse laser generator 2 emits a single beam of ultrashort pulse laser 201 towards the scanning galvanometer 4. The scanning galvanometer 4 has an X-axis polarizer 401, a Y-axis polarizer 402, and an objective lens 403. The ultrashort pulse laser 201 will perform large-interval alternating laser path ablation on the surface of the diamond sheet 8 along a preset path. Please refer to... Figure 3 and Figure 4 The scanning ablation path diagram shows the scanning process as follows:
[0035] S100: Laser scanning ablation is performed along the X-axis direction of the diamond sheet 8, maintaining a large spacing of 25-30μm, to form parallel ablation paths with equal spacing. The selection of the large spacing S is determined according to the surface roughness and surface area of the diamond sheet 8. The large spacing S is kept to increase proportionally with the roughness and surface area. The initial roughness of the diamond sheet 8 to be processed in this application is 100-700μm.
[0036] S200: After scanning and ablation to form a large-spacing path one, the X-axis polarizer 401 is adjusted so that the single beam of the ultrashort pulse laser 201 scans and ablates the diamond sheet line by line within the spacing formed by path one and the unscanned ablation position, forming a parallel and equally spaced ablation path two, and path one and path two are parallel to each other and do not intersect.
[0037] S300: After completing the scanning and ablation of path two, the Y-axis polarizer 402 of the scanning galvanometer 4 is adjusted to change the incident direction from the X-axis of the diamond sheet 8 to the Y-axis perpendicular to it, so that the ultrashort pulse laser 201 performs laser scanning and ablation along the Y-axis of the diamond sheet with a large spacing, forming a parallel and equally spaced ablation path three. The path three is perpendicular to the paths one and two and covers the surface of the diamond sheet 8.
[0038] S400: After completing the scanning and ablation of path three, adjust the Y-axis polarizer 402 so that the single beam of the ultrashort pulse laser 201 scans and ablates the diamond sheet line by line along the Y-axis direction within the spacing formed by path three and the unscanned ablation position, forming a parallel and equally spaced ablation path four. Path four is perpendicular to path one and two and parallel to path three.
[0039] The incident angle of the single beam of the ultrashort pulse laser 201 is 90 degrees, its scanning feed speed is 0.3-0.5μm / s, and its wavelength is 532nm. The feed speed is selected according to the surface roughness and surface area of the diamond sheet 8, and increases proportionally.
[0040] Because the ultrashort pulse laser 201 applied instantaneously to the surface of the diamond sheet 8 can easily cause thermal stress concentration and crack the diamond sheet 8, preheating with blue light before scanning during scanning ablation can reduce temperature differences. Furthermore, using a wide-spaced path for sequential scanning prevents localized overheating between adjacent scanning paths. Scanning ablation through paths one through four ensures a large spacing between adjacent paths while maintaining a high scanning density across the diamond sheet 8, resulting in uniform surface roughness. During the scanning ablation process, the diamond sheet 8 remains stationary, with only the scanning direction of the scanning galvanometer 4 being changed, thus improving scanning accuracy. The diamond sheet 8 after ablation treatment has a roughness of 0.5-0.9μm. This invention uses blue light as a preheating light source to form a large-size, low-energy-density light spot on the diamond sheet surface without damaging the diamond sheet substrate. Overall preheating of the diamond sheet can avoid the large temperature gradient generated during ultrashort pulse laser ablation of the diamond sheet, which could lead to diamond sheet breakage. By setting a large-pitch scanning path and using a four-step scanning method, the removal of protruding particles on the diamond surface can be improved. The method of this invention is flexible and fast to operate, and the required control system is simple and reliable, thus improving the ablation efficiency of the product.
[0041] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, and that the invention can be implemented in other specific forms without departing from its spirit or essential characteristics. Therefore, the embodiments should be considered exemplary and non-limiting in all respects, and the scope of the invention is defined by the appended claims rather than the foregoing description. Thus, all variations falling within the meaning and scope of equivalents of the claims are intended to be included within the present invention. No reference numerals in the claims should be construed as limiting the scope of the claims. Furthermore, it should be understood that although this specification describes embodiments, not every embodiment contains only one independent technical solution. This method of description is merely for clarity, and those skilled in the art should consider the specification as a whole. The technical solutions in the various embodiments can also be appropriately combined to form other embodiments that can be understood by those skilled in the art.
Claims
1. A laser processing method for improving the surface roughness of diamond, wherein the laser processing method is performed by a laser processing apparatus, the laser processing apparatus comprising a laser generator for preheating a diamond sheet, an ultrashort pulse laser generator for ablation of the diamond sheet surface, a scanning galvanometer for adjusting the scanning ablation direction of the ultrashort pulse laser, a collimating focusing lens for concentrating the heated laser beam, and a processing stage assembly for mounting and adjusting the diamond sheet, wherein a temperature sensor for real-time temperature measurement of the diamond sheet is provided on the processing stage assembly, characterized in that... The laser processing method includes the following steps: S1: After fixing the diamond sheet to be processed on the processing table assembly, adjust the collimating focusing lens to align with the surface of the diamond sheet, and use the laser generator to preheat the surface of the diamond sheet; S2: After monitoring that the surface of the diamond sheet reaches the preset temperature, the ultrashort pulse laser generator is activated to emit an ultrashort pulse laser. The scanning galvanometer makes the ultrashort pulse laser maintain the incident angle along the preset path to perform large-spacing alternating laser ablation. S3: Maintain a large spacing between each ablation path, and after alternating vertical ablation of the paths, the surface roughness of the diamond sheet reaches the preset value. The large-spacing alternating laser ablation step in S2 is as follows: S100: Laser scanning ablation is performed along the X-axis of the diamond sheet, maintaining a large spacing, to form parallel ablation paths with equal spacing. S200: Scan and ablate along the X-axis of the diamond sheet one by one within the spacing formed by the first path to form a second ablation path that is parallel to each other and equally spaced. S300: Adjust the incident direction of the scanning galvanometer so that the ultrashort pulse laser maintains a large gap along the Y-axis of the diamond sheet to perform laser scanning ablation, forming parallel and equally spaced ablation paths. S400: Scan and ablate along the Y-axis of the diamond sheet one by one within the spacing formed by the path three to form parallel and equally spaced ablation paths four. Path 1, Path 2, Path 3, and Path 4 are perpendicular to each other. The laser emitted by the laser generator in step S1 is a continuous laser with a wavelength range of 400-450nm; the laser emitted by the ultrashort pulse laser generator in step S2 is a pulsed laser with a wavelength of 532nm. The spacing between adjacent ablation paths in steps S2 and S3 is maintained in the range of 25-30 μm. In step S1, the laser generator forms a preheated spot on the surface of the diamond sheet. The diameter of the spot ranges from 1 to 4 cm, and the preheating temperature ranges from 40 to 100°C. The spot is continuously heated while the ultrashort pulse laser scans the ablation path, so that the surface temperature of the diamond sheet remains constant.
2. The laser processing method according to claim 1, characterized in that, The processing table assembly includes a processing table base and a vacuum adsorption fixture disposed on the processing table base. The diamond sheet is placed on the vacuum adsorption fixture for adsorption and fixation. The temperature sensor has a temperature sensor that monitors the surface temperature of the diamond sheet in real time and feeds it back to the laser generator.
3. The laser processing method according to claim 1, characterized in that, In step S2, the incident angle of the ultrashort pulse laser scanning and ablation of the diamond sheet surface is 90 degrees.
4. The processing method according to claim 1, characterized in that, The laser beam used for scanning ablation by the ultrashort pulse laser is a single beam, and its scanning feed speed is 0.3-0.5 μm / s.
5. The processing method according to claim 1, characterized in that, The initial roughness of the diamond sheet is 100-700 μm, and the roughness of the diamond sheet after ablation treatment is 0.5-0.9 μm.