A path planning method and path for the initial microstructure of a fused silica microlens array processed by CO2 laser rapid ablation

Abstract

The present invention provides a path planning method and path for an initial microstructure of a fused silica microlens array processed by CO2 laser rapid ablation, belonging to the technical field of optical processing. In order to solve the problem that when processing a microcolumn array by rapid material removal by CO2 laser ablation, the processed surface has excessive or insufficient ablation, resulting in roughness and unevenness, seriously affecting the quality of the microlens array. Processing experiments are carried out using two processing methods of array points and array lines, and multi-line scanning is preferably selected. The planned paths are cross trajectories and non-cross S-shaped trajectories, and the non-cross S-shaped trajectory is preferably selected. Although its effect is better, there is still a problem of uneven processed surface. It is optimized again to a non-cross point scanning starting point same-side trajectory, and the time intervals for scanning two adjacent horizontal and vertical trajectories are the same. The present invention reveals the influence of scanning along different trajectories on the processed surface morphology; solves the problem that the initial microstructure has excessive or insufficient surface ablation, resulting in roughness and unevenness, and lays a foundation for obtaining a high-quality fused silica microlens array.

Description

Technical Field

[0001] The present invention relates to the technical field of optical processing, and more particularly, to a path planning method and path for an initial microstructure of a CO2 laser rapid ablation processing fused silica microlens array. Background Art

[0002] Microlens arrays are widely used in aspects such as 3D imaging, Moiré imaging, compound eye imaging, beam shaping, fiber optic coupling connection, infrared detection, liquid crystal display, etc. At the same time, due to the characteristics of low thermal expansion coefficient, good thermal stability and chemical stability of fused silica, in order to meet the requirements of the thermal stability of optical components in high-temperature environments, microlens arrays can be processed on the surface of fused silica. For the preparation of fused silica microlens arrays, a combined method of CO2 laser ablation rapid removal and CO2 laser melting and polishing is a very promising processing method. First, irradiate the fused silica with a high-power density CO2 laser to quickly bring the material to the ablation state and achieve the rapid formation of the initial microstructure of the microlens array; secondly, irradiate the initial microstructure with a low-power density CO2 laser to gradually increase the temperature of the surface layer material and then melt and flow, and process the microlens array through the redistribution of the surface material of the initial microstructure. The determined initial microstructure is a microcolumn array similar to the microlens array structure, and the microcolumn is a square column with a square horizontal cross-section.

[0003] When preparing a fused silica microlens array using the above combined method, when using a CO2 laser to rapidly remove materials by ablation to process the microcolumn array, due to different processing trajectories, there will be problems of excessive ablation or insufficient ablation on the processing surface, resulting in rough unevenness, which seriously affects the quality of the microlens array obtained by subsequent CO2 laser melting and polishing of the microcolumn array. Summary of the Invention

[0004] The technical problem to be solved by the present invention is:

[0005] To solve the problem that when using a CO2 laser to rapidly remove materials by ablation to process a microcolumn array, there is excessive ablation or insufficient ablation on the processing surface, resulting in rough unevenness, which seriously affects the quality of the microlens array obtained by subsequent CO2 laser melting and polishing of the microcolumn array.

[0006] The technical solution adopted by the present invention to solve the above technical problem:

[0007] The present invention provides a path planning method for an initial microstructure of a CO2 laser rapid ablation processing fused silica microlens array, including the following steps:

[0008] Step 1: Perform processing experiments using two different processing methods respectively, and preferably select the processing method with better processing effects. The two processing methods include array point processing and array line processing;

[0009] Step 2: Taking the consistent machining surface height between the micro-columns on the surface of fused silica as the standard for path planning, obtain the machining effect of the CO2 laser scanned according to the planned scheme through the finite element simulation method for the machining method with better machining effect selected in Step 1, analyze the corresponding machining surface quality, and optimize to obtain the final path scheme.

[0010] Further, in Step 1, the machining methods for the array points and array lines may include single-point scanning, single-line scanning, multi-point scanning, or multi-line scanning.

[0011] Further, in Step 1, preferably, the machining methods with the machining texture not significantly changing with the increase of machining depth are single-line scanning or multi-line scanning. Single-line scanning or multi-line scanning can be selected according to the width between micro-columns and the scanning pitch. When the scanning pitch is narrow and the target width between micro-columns meeting the size and morphology requirements can be machined in one scan, single-line scanning can be selected; when the scanning pitch is wide and the target width between micro-columns meeting the size and morphology requirements cannot be machined in one scan, multi-line scanning can be selected.

[0012] Further, in Step 2, the scanning trajectories are initially divided into cross trajectories and non-cross S-shaped trajectories.

[0013] Further, in Step 2, preferably, the non-cross S-shaped trajectory with a relatively flat machining surface is selected.

[0014] Further, there is no intersection between the horizontal and vertical trajectories of the non-cross S-shaped trajectory, and the scanning starting points of the horizontal and vertical trajectories are on the same side of the material surface. When scanning the horizontal trajectory, after scanning the same row, scan the next horizontal trajectory at the set scanning pitch. The same principle applies to vertical scanning.

[0015] Further, optimize the non-cross S-shaped trajectory, and preferably select the scanning method of the non-cross scanning starting point on the same side trajectory with a more flat machining surface.

[0016] Further, when scanning the non-cross scanning starting point on the same side trajectory, control the interval time between scanning two adjacent horizontal trajectories to be the same as the interval time between two adjacent vertical trajectories, so as to make the influence of the thermal accumulation effect on the ablation depth of the horizontal and vertical machining surfaces the same.

[0017] Further, when scanning the non-cross scanning starting point on the same side trajectory, small-power ablation short lines and high-power ablation long lines can be used to make the time intervals of scanning long lines and scanning short lines the same, and the difference in the thermal accumulation effect can be reduced when scanning long lines and short lines.

[0018] A path for the initial microstructure of a CO2 laser rapid ablation machining fused silica microlens array, obtained according to the path planning method for the initial microstructure of a CO2 laser rapid ablation machining fused silica microlens array.

[0019] Compared with the prior art, the present invention has the following beneficial effects:

[0020] The present invention discloses a path planning method and path for the initial microstructure of a fused silica microlens array by rapid ablation of a CO2 laser. The two processing methods of array point and array line are used to respectively carry out processing experiments, and a processing method with better processing effect is selected. Multi-line scanning is preferred because the processing surface is relatively flat after scanning. The planned path is a cross track and a non-cross S-shaped track. Finite element simulation shows that the non-cross S-shaped track has a better effect but still has the problem of uneven processing surface. It is optimized again to a track on the same side of the non-cross point scanning starting point, and the time intervals of two adjacent horizontal and vertical tracks are the same. In addition, a short line of low-power ablation can be used. Finite element simulation shows that the optimized scanning method has the best effect and meets the process standard.

[0021] The present invention discloses a path planning method for the initial microstructure of a fused silica microlens array by rapid ablation by a CO2 laser. The method experimentally reveals the influence of two processing modes, namely, array point and array line, on the processing surface morphology. The method simulates the processing process of rapid material removal by scanning and ablating the CO2 laser along different trajectories, reveals the influence of scanning along different trajectories on the processing surface morphology, and provides a theoretical basis for better controlling the processing surface quality.

[0022] The present invention discloses a path planning method for processing the initial microstructure of a fused quartz microlens array by CO2 laser rapid ablation. The path trajectory is gradually optimized by combining a finite element simulation method, and finally a solution for the same-side trajectory of a non-intersection scanning starting point that can improve the flatness of the processed surface is planned. The method solves the problem that the initial microstructure of a target microlens array can be produced by excessive or insufficient surface ablation, resulting in roughness, in a fused quartz microlens array preparation method that combines CO2 laser rapid ablation removal with CO2 laser melting polishing, and lays a foundation for obtaining a high-quality fused quartz microlens array by CO2 laser precision polishing. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 Schematic diagram of the CO2 laser ablation rapid removal processing method in an embodiment of the present invention Figure 1 ;

[0024] Figure 2 Schematic diagram of the CO2 laser ablation rapid removal processing method in an embodiment of the present invention Figure 2 ;

[0025] Figure 3 A comparison diagram of the results of two CO2 laser ablation removal processing methods in an embodiment of the present invention;

[0026] Figure 4 The path planning and result diagram of the cross-trajectory in the embodiment of the present invention;

[0027] Figure 5 Path planning and results of the non-crossing S-shaped trajectory in the embodiment of the present invention;

[0028] Figure 6 Path planning and result diagram of the trajectory on the same side of the non-crossing scanning starting point in the embodiment of the present invention. Specific embodiments

[0029] In the description of the present invention, it should be noted that in the embodiments of the present invention, the terms "first", "second", and "third" are only used for descriptive purposes and cannot be understood as indicating or implying relative importance or implicitly indicating the quantity of the indicated technical features. Thus, the features defined with "first", "second", and "third" may explicitly or implicitly include one or more of these features.

[0030] To make the above objects, features, and advantages of the present invention more obvious and understandable, the following detailed description of the specific embodiments of the present invention is made with reference to the accompanying drawings.

[0031] Specific implementation plan one: Combined with Figures 1 to 4 As shown, the present invention provides a path planning method for the initial microstructure of a CO2 laser rapid ablation processed fused silica microlens array, including the following steps:

[0032] Step 1: Use two different processing methods to conduct processing experiments respectively, and preferably select the processing method with better processing effects. The two processing methods include array point processing and array line processing;

[0033] According to the width of the material to be removed to process the microcolumn array, select single-point scanning, single-line scanning, multi-point scanning, or multi-line scanning. For single-line scanning or multi-line scanning, single-line scanning or multi-line scanning can be selected according to the scanning pitch. When the scanning pitch is narrow and the width between the target microcolumns that can be processed in one scan meets the size and topography requirements, single-line scanning can be selected; when the scanning pitch is wide and the width between the target microcolumns that can be processed in one scan does not meet the size and topography requirements, multi-line scanning can be selected;

[0034] This application is applicable to multi-line scanning because single-point or single-line scanning cannot process the required width, and multi-point or multi-line scanning is required to ablate to obtain a wider groove;

[0035] By comparing multi-point scanning and multi-line scanning, it can be seen that in multi-point scanning, the processing texture between points is very obvious and becomes more obvious with the increase of the processing depth, resulting in a higher surface roughness of the processed surface. Although processing texture also appears in multi-line scanning, this texture does not become more obvious with the increase of the processing depth. At the same time, considering that the subsequent melting flow can remove this texture to a certain extent, therefore, the processing effect of multi-line processing can meet the process requirements of the target microlens array;

[0036] Among them, array point machining is to control the laser to continuously act at the designed position to be machined for a period of time, and then machine the next point to achieve the purpose of removing excess material; array line machining is to control the laser to move linearly on the surface to be machined at a certain speed to remove excess material;

[0037] Step 2: Perform path planning with the criterion that the machining surface heights between the micro-columns on the fused silica surface are consistent. For the machining method with better machining effect selected in Step 1, use the finite element simulation method to obtain the machining effect of the CO2 laser scanning according to the planned scheme, and analyze the corresponding machining surface quality;

[0038] First, divide according to the scanning trajectory, including intersecting trajectories and non-intersecting S-shaped trajectories, combined with Figure 2 As shown, there are intersections between the horizontal and vertical trajectories of the intersecting trajectories. Scanning along the trajectory in Figure 2 (a) in the arrow direction, the material is quickly removed by ablation to machine the micro-column array; there are no intersections between the horizontal and vertical trajectories of the non-intersecting S-shaped trajectories. Scanning along the trajectory in Figure 2 (b) in the arrow direction, the material is quickly removed by ablation. When determining the scanning order, either horizontal scanning or vertical scanning can be used first;

[0039] During the scanning process, there are no intersections between the horizontal and vertical trajectories of the trajectories on the same side of the non-intersecting scanning starting point. The scanning starting points of the horizontal and vertical trajectories are on the same side of the material surface. Scanning along the trajectory in Figure 2 (c) in the arrow direction, when scanning the horizontal trajectory, after scanning the same row, scan the next horizontal trajectory at the set scanning interval distance from it. The same principle applies to vertical scanning as to horizontal scanning;

[0040] Among them, the scanning interval can be 30μm, but the scanning interval is not a constant value. Different experimental parameters may result in different scanning intervals, which can be obtained through single-factor experiments to study the influence law of laser parameters on the single-line scanning depth and through experimental comparison;

[0041] Adopt the multi-line scanning machining method optimized in Step 1 to scan the intersecting trajectories and non-intersecting S-shaped trajectories. Through comparison with finite element simulation, it can be seen that for the micro-column array machined along the intersecting trajectory, the intersecting positions on the machining surface are over-ablated due to the thermal accumulation effect, and pits appear on the machining surface. For the micro-column array machined along the non-intersecting S-shaped trajectory, there is no over-ablation on the machining surface, but it is easy to form relatively high protrusions on the longitudinal ablation surface due to insufficient ablation, resulting in a rough and uneven machining surface;

[0042] Step 3: Optimize the scanning method with the best processing effect selected in Step 2 to obtain a scanning method for non-crossing scanning starting point on the same side of the trajectory. By controlling the scanning order and using low-power ablation for short lines and high-power ablation for long lines, where both high power and low power are selected on the premise of ablation removal, make the interval time between two adjacent horizontal trajectories close to or the same as the interval time between two adjacent vertical trajectories, so that the influence of the thermal accumulation effect on the ablation depth of the horizontal and vertical processing surfaces is close to or the same, and obtain a processing surface with as consistent a height as possible.

[0043] Embodiment

[0044] 1. Conduct processing experiments using two different processing methods respectively, and preferably select the processing method with better processing effect. The two processing methods include array point processing and array line processing;

[0045] The micro-column arrays obtained by using the array point and array line processing methods are as Figure 3 shown, Figure 3 (a) The processing texture between points on the surface processed by array point processing is very obvious and becomes more obvious with the increase of the processing depth, making the surface roughness of the processed surface higher; Figure 3 (b) There is also processing texture between lines on the surface processed by array line processing, but it will not become more obvious with the increase of the processing depth;

[0046] 2. Adopt the processing method preferably selected in 1, select the scanning trajectories of cross trajectories and non-crossing S-shaped trajectories, compare the processing effects of the two scanning trajectories through the finite element simulation method, analyze the corresponding processed surface quality, and optimize and determine the scanning trajectory on the same side of the non-crossing scanning starting point;

[0047] The simulation results of the micro-column arrays scanned along the cross trajectory and the non-crossing S-shaped trajectory are respectively as Figure 4 、 Figure 5 shown. It can be seen from Figure 4 that when the CO2 laser ablates and processes a micro-column array along the cross trajectory, the control is simple, but there is excessive ablation at the trajectory crossing position, resulting in pits. Especially when the height of the micro-column is only 38 μm, the height difference of the processed surface is as high as 30 μm;

[0048] It can be seen from Figure 5 (b) that for the longitudinally ablated surface, corresponding to the Figure 5 Y-axis direction in

[0049] Figure 2The non-crossing scan starting point same-side trajectories shown in (c) ensure that the thermal accumulation effects between the short scan lines and those between the long scan lines are similar by controlling the scan order. Small power can be used to ablate the short lines, and high power to ablate the long lines, so as to make the time intervals between the long scan lines and the short scan lines the same, reduce the difference in thermal accumulation effects between the long and short scan lines, and prevent the processed surface from being rough and uneven.

[0050] The micro-column array processed along the non-crossing scan starting point same-side trajectory is as Figure 6 shown. The processed surface has good height consistency, without problems of roughness caused by excessive or insufficient ablation, and can meet the processing requirements.

[0051] In summary, by using the array line processing method, the CO2 laser scans and ablates along the non-crossing scan starting point same-side trajectory to quickly remove materials, and can process the initial micro-structure of the fused silica microlens array with good surface consistency. There is no problem of roughness on the processed surface due to excessive or insufficient ablation, and the microlens array that meets the processing requirements can be processed by subsequent CO2 laser melting and polishing of the micro-column array.

[0052] Although the present invention is disclosed as above, the protection scope of the present invention is not limited thereto. Those skilled in the art of the present invention can make various changes and modifications without departing from the spirit and scope of the present invention, and these changes and modifications will all fall within the protection scope of the present invention.

Claims

1. A path planning method for the initial microstructure of a fused silica microlens array processed by CO2 laser rapid ablation, characterized in that, It includes the following steps: Step 1: Conduct processing experiments using two different processing methods respectively, and preferably select the processing method with better processing effect. The two processing methods include array point processing and array line processing; Preferably select the processing method whose processing texture does not change significantly with the increase of processing depth as single-line scanning or multi-line scanning. Single-line scanning or multi-line scanning can be selected according to the width between micro-columns and the scanning pitch. When the scanning pitch is narrow and the target width between micro-columns that meets the size and morphology requirements can be processed in one scan, single-line scanning can be selected; when the scanning pitch is wide and the target width between micro-columns that meets the size and morphology requirements cannot be processed in one scan, multi-line scanning can be selected; Step 2: Conduct path planning with the standard that the processing surface height between micro-columns on the fused silica surface is consistent. Obtain the processing effect of the CO2 laser scanned according to the planned scheme through the finite element simulation method for the processing method with better processing effect selected in Step 1, analyze the corresponding processing surface quality, and optimize to obtain the final path scheme; The scanning trajectory is initially divided into a cross trajectory and a non-cross S-shaped trajectory; There is no intersection between the horizontal and vertical trajectories of the non-cross S-shaped trajectory. The scanning starting points of the horizontal and vertical trajectories are on the same side of the material surface. When scanning the horizontal trajectory, after scanning the same row, scan the next horizontal trajectory at the set scanning pitch. The same principle applies to vertical scanning.

2. The path planning method for the initial microstructure of a fused silica microlens array processed by CO2 laser rapid ablation according to claim 1, characterized in that: In Step 1, the processing methods of the array points and array lines may include single-point scanning, single-line scanning, multi-point scanning or multi-line scanning.

3. The path planning method for the initial microstructure of a fused silica microlens array processed by CO2 laser rapid ablation according to claim 2, wherein: In Step 2, preferably select the non-cross S-shaped trajectory with a relatively flat processing surface.

4. The path planning method for the initial microstructure of a fused silica microlens array processed by CO2 laser rapid ablation according to claim 3, wherein: Optimize the non-cross S-shaped trajectory, and preferably select the scanning method of the non-cross scanning starting point on the same side trajectory with a smoother processing surface.

5. The path planning method for the initial microstructure of a fused silica microlens array processed by CO2 laser rapid ablation according to claim 4, characterized in that: When scanning the non-cross scanning starting point on the same side trajectory, control the interval time between scanning two adjacent horizontal trajectories to be the same as the interval time between two adjacent vertical trajectories, so as to make the influence of the thermal accumulation effect on the ablation depth of the horizontal and vertical processing surfaces the same.

6. The path planning method for the initial microstructure of a fused silica microlens array processed by CO2 laser rapid ablation according to claim 5, wherein: When scanning the non-cross scanning starting point on the same side trajectory, small-power ablation short lines and high-power ablation long lines can be used to make the time intervals of scanning long lines and short lines the same, and the difference in the thermal accumulation effect during scanning long lines and short lines can be reduced.

7. A path for the initial microstructure of a fused silica microlens array processed by CO2 laser rapid ablation, characterized in that: Obtained according to the path planning method for the initial microstructure of the CO2 laser rapid ablation processing of fused silica microlens arrays described in any one of claims 1-6.

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