Ultra-precision composite machining method and alignment method for V-shaped groove array of single crystal material

Abstract

The invention belongs to the field of processing of V-shaped groove arrays at the extreme tips of single crystal materials, and specifically discloses an ultra-precision composite processing method and an alignment method for V-shaped groove arrays of single crystal materials. After the crystal orientation of the single crystal material is determined, a femtosecond laser is used to perform processing along a direction parallel to or / and perpendicular to the crystal orientation, so as to form a microstructure array on the surface of the single crystal material; the processed single crystal material is wet-etched in anisotropic etching liquid; the single crystal material obtained is placed on a tooling table of a slitting processing system, and the V-shaped grooves are further processed by a diamond tool of the slitting processing system. During processing, the cutting process is performed after the tip of the diamond tool is aligned with the bottom of the groove.

Description

Technical Field

[0001] The invention relates to the field of processing a single crystal material V-shaped groove array at a pole tip, and in particular to an ultra-precision composite processing method and an alignment method for a single crystal material V-shaped groove array. Background Art

[0002] At present, there are various processing methods for V-shaped groove arrays of single crystal materials, mainly including precision machining and micromachining methods, among which the micromachining methods mainly include etching technology, laser direct writing technology and their combination technology; among which femtosecond laser assisted wet etching technology can utilize the anisotropic corrosion characteristics of single crystal materials in a specific solution without preparing a mask during the material processing process, and efficiently obtain a high-precision high-aspect ratio V-shaped groove array; for example, patent CN115535959A discloses a wet etching assisted femtosecond laser processing method for a single crystal silicon microstructure array, which mainly includes, after determining the crystal orientation of the single crystal silicon, using a femtosecond laser to perform processing along a direction parallel to or / and perpendicular to the crystal orientation to form a microstructure array on the surface of the single crystal silicon; the processed single crystal silicon is placed on Wet etching is performed in anisotropic etching solution. This method combines femtosecond laser with wet etching technology. However, due to the acidity and alkalinity of the etchant and the anisotropy of the material, the etching rates in different crystal directions are different during the etching process, and the side walls of the processed V-shaped grooves may be uneven. Therefore, the V-shaped grooves need to be processed again. However, the current prior art does not disclose what process is used for further processing. At the same time, when the V-shaped grooves are processed again, the single crystal material processed by the previous process needs to be transferred to the next processing platform. After the transfer, the problem of precise alignment of the processing tool with the bottom of the V-shaped groove is faced. If the processing tool cannot be aligned with the bottom of the V-shaped groove, not only can the unevenness of the side walls of the V-shaped groove not be solved, but the previously processed V-shaped groove array will also be destroyed. Summary of the invention

[0003] In order to solve the problems existing in the prior art, the present invention proposes an ultra-precision composite processing method and alignment method for a V-shaped groove array of a single crystal material. After aligning the tip of the diamond tool with the bottom of the groove after femtosecond laser wet etching, flycutting is performed to obtain a V-shaped groove array structure with a smooth groove surface and a complete contour.

[0004] In order to achieve the above object, the technical solution adopted by the present invention is as follows:

[0005] In a first aspect, the present invention provides an ultra-precision composite machining alignment method for a V-shaped groove array of a single crystal material, as follows:

[0006] placing a single crystal material having a V-shaped groove array processed thereon on a tooling table;

[0007] The laser focus of the spectral confocal displacement sensor is moved to a specified position, and the bottom coordinates of the specified V-shaped groove are obtained by the spectral confocal displacement sensor;

[0008] The tool is rotated to carve a V-shaped groove on the surface of the single crystal material sample, and the spectral confocal displacement sensor is moved to the bottom of the V-shaped groove to obtain the coordinates of the tool tip, thereby obtaining the relative coordinate relationship between the tool tip and the bottom of the V-shaped groove;

[0009] The tool tip is precisely aligned with the specified V-groove bottom according to the relative coordinate relationship.

[0010] As a further technical solution, a method for obtaining the bottom coordinates of a specified V-shaped groove by using a spectral confocal displacement sensor is as follows:

[0011] Move the laser focus of the spectral confocal displacement sensor to the intersection edge of the first V-shaped groove and the top surface flat section of the single crystal material for rough alignment;

[0012] The spectral confocal displacement sensor is made to perform interpolation motion along the cross-sectional shape of the ideal V-shaped groove on the top surface of the single crystal material to obtain a deviation image between the actual groove profile and the movement trajectory of the spectral confocal displacement sensor; the moving starting point of the spectral confocal displacement sensor is adjusted according to the deviation image to align it with the intersection edge of the first V-shaped groove and the plane segment of the top surface of the single crystal material, thereby obtaining the bottom coordinates of the first V-shaped groove.

[0013] In a second aspect, the present invention provides an ultra-precision composite machining alignment method for a V-shaped groove array of a single crystal material, as follows:

[0014] placing a single crystal material having a V-shaped groove array processed thereon on a tooling table;

[0015] Move two identical image acquisition devices to a set position above the bottom of a specified V-shaped groove and photograph it to obtain the bottom coordinates of the specified V-shaped groove;

[0016] Rotate the tool to carve a V-shaped groove on the surface of the single crystal material, move the two image acquisition devices to a set position above the bottom of the V-shaped groove and photograph it to obtain the coordinates of the tool tip, thereby obtaining the relative coordinate relationship between the tool tip and the coordinates of the bottom of the specified V-shaped groove;

[0017] The tool tip is precisely aligned with the specified V-groove bottom according to the relative coordinate relationship.

[0018] In a third aspect, based on the above alignment method, the present invention further provides an ultra-precision composite processing method for a single crystal material V-shaped groove array, comprising the following steps:

[0019] Step 1: Processing a V-shaped groove array in a single crystal material using a wet etching assisted femtosecond laser processing method;

[0020] Step 2: Place the single crystal material obtained in step 1 on the tooling table of the slitting processing system, and use the method described above to accurately align the tip of the tool with the bottom of the specified V-shaped groove;

[0021] Step 3: Use the cutting tool of the slitting processing system to further process the V-shaped groove.

[0022] As a further technical solution, the slitting processing system includes a control system and an X-axis drive system, a Y-axis drive system, and a Z-axis drive system. A tooling table is installed on the Z-axis drive system, and the single crystal material sample is installed on the tooling table; the rotating spindle is arranged on the Y-axis drive system, the Y-axis drive system is arranged on the X-axis drive system, a flying cutter disc is installed on the rotating spindle, and a diamond tool is arranged on the flying cutter disc.

[0023] As a further technical solution, the position of the diamond tool is adjusted to be perpendicular to the XOZ plane; the single crystal material sample processed in step 2 is clamped above the tooling table, and the groove extension direction is parallel to the X-axis; the tool is moved in the X and Y planes through the control system, and the single crystal material sample reciprocates in the Z direction.

[0024] Furthermore, the specific alignment method is as follows:

[0025] The spectral confocal displacement sensor is fixed on the Y-axis driving system, and the laser is vertically incident on the surface of the single crystal material sample;

[0026] Controlling the X-axis drive system and the Z-axis drive system to move the laser focus in the XZ plane to the edge where the first V-shaped groove after processing and the top surface plane section of the single crystal material intersect;

[0027] The slitting processing system is controlled to make the spectral confocal displacement sensor perform interpolation movement along the cross-sectional shape of the ideal V-shaped groove in the YOZ plane; the moving starting point of the spectral confocal displacement sensor is adjusted by observing the output image of the spectral confocal displacement sensor so that it is aligned with the edge where the first V-shaped groove and the plane segment of the top surface of the single crystal material intersect, thereby obtaining the bottom coordinates of the first V-shaped groove;

[0028] The flying cutter disc is rotated to carve a V-shaped groove on the surface of the single crystal material sample, and the spectral confocal displacement sensor is moved to the bottom of the V-shaped groove to obtain the coordinates of the tool tip, thereby obtaining the relative coordinate relationship between the tool tip and the bottom of the first V-shaped groove;

[0029] The slitting processing system accurately aligns the tool tip with the bottom of the first V-shaped groove based on the relative coordinate relationship.

[0030] Furthermore, the specific alignment method is as follows:

[0031] Fix two identical image acquisition devices on the Y-axis drive system.

[0032] Controlling the X-axis drive system, the Y-axis drive system, and the Z-axis drive system, moving the image acquisition device to a set position above the bottom of the first V-shaped groove and photographing it, to obtain the coordinates of the bottom of the first V-shaped groove;

[0033] Rotate the flying cutter disc to carve a V-shaped groove on the surface of the single crystal material, move two image acquisition devices to the bottom of the V-shaped groove, obtain the tool tip coordinates, and thus obtain the relative coordinate relationship between the tool tip and the groove bottom coordinates of the first V-shaped groove;

[0034] The tool tip is precisely aligned with the specified V-groove bottom according to the relative coordinate relationship.

[0035] As a further technical solution, the rotating spindle drives the flying cutter disc to rotate, and the tool is fed along the direction of the V-shaped groove by controlling the X-axis. The tool and the surface of the V-shaped groove interfere with each other, resulting in material removal, and the trimming of the first V-shaped groove is completed; then, the tool is lifted, and the Z-axis is controlled to move the diamond tool a V-shaped groove spacing in the direction of the rotating spindle axis, and then the tool is dropped to process the second V-shaped groove. This method is used until all V-shaped grooves are processed.

[0036] As a further technical solution, the tool tip arc radius is less than or equal to 1 μm, and the obtained V-shaped groove bottom angle arc radius is less than 1 μm.

[0037] The beneficial effects of the present invention are as follows:

[0038] The present invention proposes two ultra-precision composite machining alignment methods for single crystal material V-groove arrays. Both methods first obtain the coordinates of the bottom of a specified V-groove through an image acquisition device or a spectral confocal displacement sensor, and then obtain the coordinates of the tool tip by scratching a groove on the surface of a single crystal material sample, thereby obtaining the relative coordinate relationship between the tool tip and the bottom of the specified V-groove. According to the relative coordinate relationship, the tool and the specified V-groove can be accurately aligned, providing a positioning basis for the next step of process processing and ensuring the processing accuracy of subsequent processes.

[0039] 2. The present invention, under the premise of realizing alignment between the tool and the V-shaped groove, can quickly prepare a V-shaped groove array with smooth sidewalls, straight lines and good consistency by combining fly cutting processing, and the processing efficiency is greatly improved. Specifically, the processing method of the V-shaped groove array assisted by femtosecond laser wet etching proposed in the present invention is:

[0040] Before fly-cutting, most of the material has been removed by femtosecond laser wet etching. Therefore, the contact area and force between the tool and the workpiece are reduced during the fly-cutting process. The defects such as cracks and chipping on the workpiece surface can be reduced during fly-cutting, which is beneficial to the processing of micro-groove structures on the surfaces of hard and brittle materials. It solves the problem of efficient and high-quality preparation of micro-structures on the surfaces of hard and brittle materials that are difficult to process, and reduces the repeated positioning errors of the slitting processing system and the errors introduced by cyclic processing. At the same time, combined with the tool alignment method of the present application, a V-shaped groove array with smooth side walls, straight lines and good consistency can be quickly prepared, and the processing efficiency is greatly improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] Figure 1 This is a picture of a V-groove array on the surface of single-crystal silicon;

[0042] Figure 2 Schematic diagram of the arrangement of V-groove arrays for ultra-precision machining slitting system fly-cutting technology;

[0043] Figure 3 Schematic diagram of spectral confocal displacement sensor auxiliary alignment;

[0044] Figure 4 This is a schematic diagram of high-precision CCD camera-assisted alignment;

[0045] Figure 5 Tips for trimming V-shaped grooves for flying cutters Figure 1 ;

[0046] Figure 6 Tips for trimming V-shaped grooves for flying cutters Figure 2 ;

[0047] In the figure: 1. rotating spindle, 2. flying cutter disc, 3. diamond tool, 4. single crystal material sample, 5. tooling table, 6. spectral confocal displacement sensor, 7. CCD camera, 8. coaxial light source, 9. groove top, 10. groove bottom, 11. V-shaped groove array, 12. laser. DETAILED DESCRIPTION

[0048] It should be noted that the following detailed descriptions are illustrative and intended to provide further explanation of the present invention. Unless otherwise specified, all technical and scientific terms used in the present invention have the same meanings as those commonly understood by those skilled in the art to which the present invention belongs.

[0049] It should be noted that the terms used herein are only for describing specific embodiments and are not intended to limit the exemplary embodiments according to the present invention. As used herein, unless otherwise explicitly stated in the present invention, the singular form is also intended to include the plural form. In addition, it should be understood that when the terms "include" and / or "include" are used in this specification, it indicates the presence of features, steps, operations, devices, components and / or combinations thereof;

[0050] The single crystal material in the present invention includes single crystal silicon, single crystal silicon carbide or single crystal aluminum oxide, etc., and a V-shaped groove array is processed on its surface, which can be widely used in optoelectronic devices, microelectronic micro-electromechanical systems, biological detection and thermal management and other fields.

[0051] Example 1

[0052] As introduced in the background technology, single crystal silicon is the basic material for manufacturing microstructure molds. During molding, in order to prevent the mold from sticking to the glass during the molding process, it is usually necessary to process a V-shaped groove array 11 thereon. In order to realize the processing of the V-shaped groove array 11, a wet etching assisted femtosecond laser processing method for a single crystal silicon microstructure array is disclosed in patent CN115535959A. The method mainly includes: after determining the crystal orientation of the single crystal silicon, using a femtosecond laser to process in a direction parallel to or / and perpendicular to the crystal orientation to form a microstructure array on the surface of the single crystal silicon; wet etching the processed single crystal silicon in an anisotropic etching solution. The method combines the femtosecond laser with the wet etching technology, but due to the acidity and alkalinity of the etchant and the anisotropic nature of the material, the microstructure array is formed on the surface of the single crystal silicon. The anisotropy leads to different etching rates in different crystal directions during the etching process, and the sidewalls of the processed V-shaped grooves may be uneven; therefore, the V-shaped grooves need to be processed again; however, when processing the V-shaped grooves, the single crystal material processed by the previous process needs to be transferred to the next processing platform. After the transfer, the problem of accurate alignment of the processing tool with the bottom of the V-shaped groove is faced. If the processing tool cannot be aligned with the bottom of the V-shaped groove, not only can the unevenness of the sidewalls of the V-shaped grooves not be solved, but the V-shaped groove array 11 that has been processed previously will also be destroyed. Therefore, this embodiment provides an ultra-precision composite processing alignment method for a V-shaped groove array 11 of a single crystal material, which specifically includes the steps of:

[0053] The single crystal material that has been preliminarily processed with the V-shaped groove array 11 is placed on the tooling table 5;

[0054] Move the laser focus of the spectral confocal displacement sensor to the intersection edge of the first groove and the top surface plane section of the single crystal material for rough alignment;

[0055] The spectral confocal displacement sensor is made to perform interpolation motion along the ideal V-shaped groove cross-section shape on the top surface of the single crystal material to obtain a deviation image between the actual groove profile and the movement trajectory of the spectral confocal displacement sensor; the moving starting point of the spectral confocal displacement sensor is adjusted according to the deviation image to align it with the intersection edge of the first V-shaped groove and the plane segment on the top surface of the single crystal material, thereby obtaining the bottom coordinates of the first V-shaped groove.

[0056] The tool is rotated to carve a V-shaped groove on the surface of the single crystal material sample 4, and the spectral confocal displacement sensor is moved to the bottom of the V-shaped groove to obtain the coordinates of the tool tip, thereby obtaining the relative coordinate relationship between the tool tip and the bottom of the V-shaped groove;

[0057] Then align the tip of the tool with the bottom of the V-groove.

[0058] The system corresponding to the above method can be referred to as Figure 2 As shown, it includes an X / Y / Z three-axis drive system, and a single crystal material sample 4 is installed on a tooling table 5 of the Z-axis drive system; a rotating spindle 1 is set on a Y-axis drive system, and the Y-axis drive system is set on an X-axis drive system; a flying cutter disc 2 is installed on the rotating spindle 1, and a diamond tool 3 is set on the flying cutter disc 2. The diamond tool 3 with a very small tip arc radius (the tip arc radius is less than or equal to 1μm) is installed on the rotating spindle 1 by means of the flying cutter disc 2, and the tool position is adjusted to be perpendicular to the XOZ plane. The processed single crystal material sample 4 is clamped above the tooling table 5, and the groove extension direction is parallel to the X-axis. By controlling the guide rail of the ultra-precision machining and slitting system, the diamond tool 3 can move in the X and Y planes, and the single crystal material sample 4 can reciprocate in the Z direction. A spectral confocal displacement sensor 6 is used to align the tip of the diamond tool 3 with the bottom of the first V-shaped groove:

[0059] like Figure 3As shown, the spectral confocal displacement sensor 6 is fixed on the Y axis by a fixing frame, and the laser 12 with a spot diameter of 8μm is vertically incident on the surface of the single crystal material sample 4. First, the light spot is roughly aligned with the intersection edge of the first V-shaped groove and the plane segment. Observe with the naked eye, control the X and Z axes to move the focus of the laser 12 in the XZ plane to the intersection edge of the first V-shaped groove and the plane segment after processing. Secondly, the light spot is precisely aligned with the intersection edge of the first V-shaped groove and the plane segment. Control the machine tool to make the spectral confocal displacement sensor interpolate along the ideal V-shaped groove cross-sectional shape in the YOZ plane to obtain the deviation image of the actual groove profile and the movement trajectory of the spectral confocal displacement sensor. If the starting point of the movement of the spectral confocal displacement sensor is aligned with the intersection edge of the first V-shaped groove and the plane segment, the image output by the sensor at this time is the deviation between the actual groove profile and the ideal V-shaped groove cross-sectional shape, and the image should fluctuate within a certain range. On the contrary, during the movement of the spectral confocal displacement sensor, its output image will change significantly. Therefore, by observing the output image of the spectral confocal displacement sensor, the starting point of the spectral confocal displacement sensor can be adjusted to align it with the intersection edge of the first V-shaped groove and the plane segment, and then the bottom coordinates of the first V-shaped groove can be obtained. Afterwards, the existing positions of the tool and the sensor are kept unchanged, and the flying cutter disk 2 is rotated to carve a V-shaped groove on the plane segment of the single crystal material. The spectral confocal displacement sensor is moved to the bottom of this V-shaped groove to obtain the tool tip coordinates, thereby obtaining the relative coordinate relationship between the tool tip and the bottom of the first V-shaped groove, and then the machine tool can be controlled to align the tool tip with the bottom of the first V-shaped groove. Since the subsequent groove morphology is the same as the first V-shaped groove morphology, the bottom coordinates of each subsequent groove differ from the bottom coordinates of the previous groove by a distance of a groove spacing perpendicular to the extension direction of a single groove, and no re-alignment is required during processing.

[0060] The ultra-precision composite machining alignment method for the single crystal material V-groove array 11 proposed in this embodiment first obtains the bottom coordinates of the V-groove through a spectral confocal displacement sensor, and then obtains the tool tip coordinates by scratching a groove on the surface of the single crystal material sample 4, thereby obtaining the relative coordinate relationship between the tool tip and the bottom of the V-groove. According to the relative coordinate relationship, the tool and the V-groove can be accurately aligned, providing a positioning basis for the next step of process processing and ensuring the processing accuracy of subsequent processes.

[0061] Example 2

[0062] This embodiment also provides another method for aligning the tool tip with the bottom of the V-shaped groove using an image acquisition device; the system based on this method is the same as that in Embodiment 1, which will not be described in detail here, and specifically includes the following steps:

[0063] The single crystal material processed with the V-shaped groove array 11 is placed on the tooling table 5;

[0064] Move two identical image acquisition devices to a set position above the bottom of a specified V-shaped groove and photograph it to obtain the bottom coordinates of the specified V-shaped groove;

[0065] Rotate the tool to carve a V-shaped groove on the surface of the single crystal material, move the two image acquisition devices to a set position above the bottom of the V-shaped groove and photograph it to obtain the coordinates of the tool tip, thereby obtaining the relative coordinate relationship between the tool tip and the bottom coordinates of the specified V-shaped groove;

[0066] The tool tip is precisely aligned with the specified V-groove bottom according to the relative coordinate relationship.

[0067] Furthermore, the image acquisition device of this embodiment uses a high-precision CCD camera 7 to align the tip of the knife with the bottom of the V-shaped groove, and combines Figure 4 To explain: Use a fixing frame to fix two CCD cameras 7 of the same model on the Y axis and keep them on the same horizontal plane. First, control the X, Y, and Z axes to move the two CCD cameras 7 to the top of the bottom of the first V-shaped groove and shoot it to obtain the groove image. Use the binocular vision calibration program to obtain the coordinates of the bottom of the first V-shaped groove. After that, rotate the flying cutter disk 2 to carve a groove on the plane section of the single crystal material, move the two CCD cameras 7 to the bottom of this groove, and use the same method as before to obtain the tool tip coordinates, thereby obtaining the relative coordinate relationship between the tool tip and the bottom of the first V-shaped groove, and then control the machine tool to align the tool tip with the bottom of the first V-shaped groove. Similar to the use of spectral confocal displacement sensors, there is no need to align again when processing subsequent grooves.

[0068] In the present invention, fly cutting is performed after the tool tip is aligned with the bottom of the first V-shaped groove. The main shaft drives the fly cutter disc 2 to rotate at high speed, and the tool is fed along the V-shaped groove direction by controlling the X-axis drive device. The tool and the surface of the V-shaped groove interfere with each other, resulting in material removal, and the trimming of a V-shaped groove is completed. Afterwards, the tool is lifted, and the Z axis is controlled to move the tool in the direction of the machine tool spindle axis by a groove spacing, and then the tool is dropped to process the second V-shaped groove. The processing of each subsequent groove is consistent with the processing method of the first two grooves.

[0069] The ultra-precision composite machining alignment method for the single crystal material V-groove array 11 proposed in this embodiment first obtains the bottom coordinates of the first V-groove through an image acquisition device, and then obtains the tool tip coordinates by scratching a groove on the surface of the single crystal material sample 4, thereby obtaining the relative coordinate relationship between the tool tip and the bottom of the first V-groove. According to the relative coordinate relationship, the tool and the first V-groove can be accurately aligned, providing a positioning basis for the next step of process processing and ensuring the processing accuracy of subsequent processes.

[0070] Example 3

[0071] Based on the tool alignment method disclosed in Example 1 and Example 2, this embodiment also proposes an ultra-precision composite processing method for a single crystal material V-shaped groove array 11. This method combines the advantages of high efficiency, simple process and high precision of femtosecond laser wet etching and fly cutting technology, and can efficiently obtain a V-shaped groove array 11 with a good profile. First, the femtosecond laser wet etching technology proposed in the patent (CN115535959A) is used to perform preliminary processing on the groove structure. The femtosecond laser ablates the material in a direction parallel or perpendicular to a certain crystal direction to change its structure, and then uses KOH solution to perform wet etching in the laser processing area, without the need to prepare a mask and achieve the removal of most of the material. After that, the fly cutting technology is used to trim the groove so that the cutting direction is parallel to the groove extension direction, thereby obtaining a V-shaped groove with smooth side walls, straight lines and good consistency. In this processing process, since the V-shaped groove has been initially formed after the femtosecond laser wet etching process, less material needs to be removed in the subsequent fly cutting process, which reduces tool wear and improves processing efficiency.

[0072] Before flycutting the microgrooves after femtosecond laser wet etching, it is necessary to align the tool tip with the bottom of the microgrooves to ensure that the subsequent processing is carried out smoothly according to the established procedure; therefore, the ultra-precision composite processing method of the single crystal material V-groove array 11 proposed in this embodiment not only combines femtosecond laser wet etching with flycutting technology, but also considers the problem of tool alignment in the process of combining the two technologies. The specific method used is as follows:

[0073] The ultra-precision composite processing method of the single crystal material V-shaped groove array 11 proposed in this embodiment is as follows:

[0074] The object to be processed in this embodiment is a V-shaped groove array 11 on the surface of a single crystal material after preliminary processing by femtosecond laser wet etching, such as Figure 1 As shown. The pulse width of the laser in the femtosecond laser micromachining system is 35 fs, the wavelength is 800nm, and the maximum repetition rate is 1 KHz. The mass fraction of the KOH solution is 20%-40%, the etching temperature is 20℃-80℃, and the etching time is 1min-12h.

[0075] The V-shaped groove is further processed by using fly cutting technology. During this process, a processing system is required. Figure 2As shown, it includes an X / Y / Z three-axis drive system, and a single crystal material sample 4 is installed on the Z-axis drive system; a rotating spindle 1 is set on the Y-axis drive system, and the Y-axis drive system is set on the X-axis drive system; a flying cutter disc 2 is installed on the rotating spindle 1, and a diamond tool 3 is set on the flying cutter disc 2. The diamond tool 3 with a very small tip arc radius (the tip arc radius is less than or equal to 1μm) is installed on the rotating spindle 1 by relying on the flying cutter disc 2, and the tool position is adjusted to be perpendicular to the XOZ plane. The processed single crystal material sample 4 is clamped above the tooling table 5, and the groove extension direction is parallel to the X-axis. By controlling the guide rail of the ultra-precision machining slitting system, the tool can move in the X and Y planes, and the single crystal material sample 4 can reciprocate in the Z direction.

[0076] Obtain the flatness error of the single crystal material specimen. Rotate the spindle 1 so that the tool is at the lower end of the fly cutter disc 2. Lock the rotating spindle 1, and control the slitting system so that the tool cuts in the plane area of ​​the single crystal material sample 4 along the direction parallel and perpendicular to the groove extension direction. Afterwards, use the spectral confocal displacement sensor 6 to measure along the scratching track to obtain the flatness error of the single crystal material sample 4. The obtained flatness error can be input into the subsequent processing program for compensation.

[0077] Select a suitable diamond tool 3. Since most of the material has been removed by femtosecond laser wet etching technology, the amount of material required to be removed in the subsequent fly-cutting process is reduced, and the wear of the tool during the fly-cutting of single crystal materials is effectively reduced. Therefore, during the fly-cutting process, a diamond tool 3 with a very small tool tip arc radius can be selected for long-term cutting.

[0078] Align the tip of the diamond tool 3 with the bottom of the groove. The present invention proposes to use a spectral confocal displacement sensor 6 and a high-precision CCD camera 7 for in-situ alignment, which greatly improves the alignment accuracy and efficiency. The following describes two in-situ alignment methods respectively;

[0079] The first method: using the spectral confocal displacement sensor 6 to align the tool tip with the bottom of the groove

[0080] like Figure 3As shown, the spectral confocal displacement sensor 6 is fixed on the Y axis by a fixed frame, and the laser 12 with a spot diameter of 8μm is vertically incident on the surface of the single crystal material. First, the light spot is roughly aligned with the intersection edge of the first groove and the plane segment. Observe with the naked eye, control the X and Z axes to move the focus of the laser 12 in the XZ plane to the intersection edge of the first groove and the plane segment after processing. Secondly, the light spot is precisely aligned with the intersection edge of the first groove and the plane segment. Control the machine tool to make the spectral confocal displacement sensor 6 interpolate along the ideal V-shaped groove cross-sectional shape in the YOZ plane to obtain the deviation image of the actual groove profile and the movement trajectory of the spectral confocal displacement sensor 6. If the starting point of the movement of the spectral confocal displacement sensor 6 is aligned with the intersection edge of the first groove and the plane segment, the image output by the sensor at this time is the deviation between the actual groove profile and the ideal V-shaped groove cross-sectional shape, and the image should fluctuate within a certain range. On the contrary, during the movement of the spectral confocal displacement sensor 6, its output image will change significantly. Therefore, by observing the output image of the spectral confocal displacement sensor 6, the moving starting point of the spectral confocal displacement sensor 6 can be adjusted to align it with the intersection edge of the first groove and the plane segment, and then the coordinates of the bottom of the first groove can be obtained. Afterwards, the existing positions of the tool and the sensor are kept unchanged, and the flying cutter disc 2 is rotated to carve a groove on the plane segment of the single crystal material. The spectral confocal displacement sensor 6 is moved to the bottom of this groove to obtain the coordinates of the tool tip, thereby obtaining the relative coordinate relationship between the tool tip and the groove bottom, and then the machine tool can be controlled to align the tool tip with the groove bottom. Since the subsequent groove morphology is the same as the first groove morphology, the coordinates of the bottom of each subsequent groove differ from the coordinates of the bottom of the previous groove by a distance of a groove spacing perpendicular to the extension direction of a single groove, and no re-alignment is required during processing.

[0081] In the second method, a high-precision CCD camera 7 is used to align the tool tip with the bottom of the V-shaped groove.

[0082] like Figure 4 As shown, two CCD cameras 7 of the same model are fixed on the Y axis by a fixing frame and kept on the same horizontal plane. In order to ensure the clarity of the shooting, a coaxial light source 8 is configured;

[0083] First, control the X, Y, and Z axes to move the two cameras above the bottom of the first groove and take a picture of it to obtain the groove image. Use the binocular vision calibration program to obtain the coordinates of the bottom of the first groove. After that, rotate the flying cutter disc 2 to carve a groove on the plane section of the single crystal material, move the two CCD cameras 7 to the bottom of this groove, and use the same method as before to obtain the coordinates of the tool tip, thereby obtaining the relative coordinate relationship between the tool tip and the bottom of the groove, and then control the machine tool to align the tool tip with the bottom of the groove. Similar to the use of the spectral confocal displacement sensor 6, there is no need to align again when processing subsequent grooves.

[0084] In the present invention, fly cutting is performed after the tool tip is aligned with the bottom of the groove. The spindle drives the fly cutter disc 2 to rotate at high speed, and the tool is fed along the groove direction by controlling the X-axis drive device. The tool and the groove surface interfere with each other, resulting in material removal, and the trimming of one groove is completed. After that, the tool is lifted, and the Z axis is controlled to move the tool in the direction of the machine tool spindle axis by a groove spacing, and then the tool is dropped to process the second groove. Figure 5 , Figure 6 The processing of each subsequent groove is the same as the processing of the first two grooves.

[0085] In the present invention, fly cutting is performed after the tool tip is aligned with the bottom of the groove. The rotating spindle 1 drives the fly cutter disc 2 to rotate at high speed, and the tool is fed along the groove direction by controlling the X-axis drive device. The tool and the groove surface interfere with each other, resulting in material removal, and the trimming of one groove is completed. After that, the tool is lifted, and the Z axis is controlled to move the tool in the axial direction of the rotating spindle 1 by a groove spacing, and then the tool is dropped to process the second groove. Figure 5 , Figure 6 The processing of each subsequent groove is the same as the processing of the first two grooves.

[0086] When the V-shaped groove is processed by the processing method proposed by the present invention, most of the material has been removed by the femtosecond laser wet etching technology. Compared with directly processing the V-shaped groove by the fly cutting technology, the contact area between the tool and the workpiece, the cutting heat and the cutting force are all reduced during the cutting process. Therefore, when the fly cutting method proposed by the present invention is used for fly cutting, a higher feed rate (3-8 mm / min) can be used to obtain a V-shaped groove with good surface roughness under the condition that other processing parameters are the same, thereby improving the processing efficiency.

[0087] Furthermore, this embodiment also discloses a single crystal material, and the V-shaped groove array 11 on the surface of the single crystal material is obtained by the ultra-precision composite processing method of the V-shaped groove array 11 of the single crystal material. The single crystal material can be used as a mold in the glass molding process, a V-shaped groove light absorber in a micro solar cell, a plasma optical structure in a surface plasma resonance sensor, and an optical element in a micro-optical system.

[0088] After fly-cutting, a V-shaped groove array 11 with a groove width of 30-50 μm, a groove depth (the distance from the groove top 9 to the groove bottom 10) of 10-100 μm, a groove bottom angle arc radius of less than 1 μm, smooth side walls, straight lines and good consistency can be obtained. The V-shaped groove array 11 can be used as a substrate for an optical fiber array, which helps to accurately position the optical fiber at its front end and improves the alignment accuracy between the optical fiber array and the planar optical waveguide device.

[0089] The V-groove array 11 processing method proposed in this embodiment has removed most of the material by femtosecond laser wet etching before fly-cutting. Therefore, the contact area and force between the tool and the workpiece are reduced during the fly-cutting process. The defects such as cracks and chipping on the workpiece surface can be reduced during fly-cutting, which is beneficial to the processing of micro-groove structures on the surfaces of hard and brittle materials, and solves the problem of efficient and high-quality preparation of micro-structures on the surfaces of hard and brittle materials that are difficult to process.

[0090] The present embodiment proposes a method for processing the V-shaped groove array 11 by using femtosecond laser wet etching to assist fly cutting. Before fly cutting, most of the material is removed by using femtosecond laser wet etching technology. Compared with the traditional fly cutting process, this method removes less material, which can effectively reduce the wear of the tool during the fly cutting of hard and brittle materials, extend the service life of the tool, and reduce production costs.

[0091] The processing method of the femtosecond laser wet etching assisted fly-cutting V-groove array 11 proposed in this embodiment has a simple process and high precision. Most of the materials have been removed by femtosecond laser wet etching during the processing, which reduces the repeated positioning error of the slitting processing system and the error introduced by the cyclic processing. The V-groove array 11 with smooth side walls, straight lines and good consistency can be quickly prepared, and the processing efficiency is greatly improved.

Claims

1. An ultra-precision composite machining alignment method for a V-shaped groove array of a single crystal material, characterized in that: as follows: placing a single crystal material having a V-shaped groove array processed thereon on a tooling table; The laser focus of the spectral confocal displacement sensor is moved to the specified V-shaped groove position, and the groove bottom coordinates of the specified V-shaped groove are obtained by the spectral confocal displacement sensor; the method for obtaining the groove bottom coordinates of the specified V-shaped groove by the spectral confocal displacement sensor is as follows: the laser focus of the spectral confocal displacement sensor is moved to the intersection edge position of the first V-shaped groove and the top surface plane segment of the single crystal material, and rough alignment is performed; the spectral confocal displacement sensor is made to perform interpolation movement along the ideal V-shaped groove cross-sectional shape on the top surface of the single crystal material to obtain a deviation image of the actual groove profile and the movement trajectory of the spectral confocal displacement sensor; the movement starting point of the spectral confocal displacement sensor is adjusted according to the deviation image to align it with the intersection edge of the first V-shaped groove and the top surface plane segment of the single crystal material, thereby obtaining the groove bottom coordinates of the first V-shaped groove; The tool is rotated to carve a V-shaped groove on the surface of the single crystal material, and the spectral confocal displacement sensor is moved to the bottom of the V-shaped groove to obtain the coordinates of the tool tip, thereby obtaining the relative coordinate relationship between the tool tip and the specified V-shaped groove bottom; The tool tip is precisely aligned with the specified V-groove bottom according to the relative coordinate relationship.

2. An ultra-precision composite processing method for a V-shaped groove array of a single crystal material, characterized in that: The following steps are involved: Step 1: Processing a V-shaped groove array on a single crystal material using a wet etching assisted femtosecond laser processing method; Step 2: placing the single crystal material obtained in step 1 on a workbench of a slitting processing system, and using the alignment method described in claim 1 to accurately align the tip of a tool with the bottom of a designated V-shaped groove; Step 3: Use the cutting tool of the slitting processing system to further process the V-shaped groove.

3. The ultra-precision composite processing method of a single crystal material V-shaped groove array according to claim 2, characterized in that: The slitting processing system includes a control system and an X-axis drive system, a Y-axis drive system, and a Z-axis drive system. A tooling table is installed on the Z-axis drive system, and the single crystal material is installed on the tooling table; the rotating spindle is arranged on the Y-axis drive system, and the Y-axis drive system is arranged on the X-axis drive system. A flying cutter disc is installed on the rotating spindle, and a tool is arranged on the flying cutter disc.

4. The ultra-precision composite processing method of a single crystal material V-shaped groove array according to claim 3, characterized in that: In step 3, the tool position is adjusted to be perpendicular to the XOZ plane; the single crystal material processed in step 1 is clamped above the tooling table, and the groove extension direction is parallel to the X axis; the tool is moved in the X and Y planes through the control system, and the single crystal material reciprocates in the Z direction.

5. The ultra-precision composite processing method of a single crystal material V-shaped groove array according to claim 3, characterized in that: The specific alignment method of step 2 is as follows: The spectral confocal displacement sensor is fixed on the Y-axis driving system, and the laser is vertically incident on the surface of the single crystal material; Controlling the X-axis drive system and the Z-axis drive system to move the laser focus in the XZ plane to the edge where the first V-shaped groove after processing and the top surface plane section of the single crystal material intersect; The slitting processing system is controlled to make the spectral confocal displacement sensor perform interpolation movement along the cross-sectional shape of the ideal V-shaped groove in the YOZ plane; the moving starting point of the spectral confocal displacement sensor is adjusted by observing the output image of the spectral confocal displacement sensor so that it is aligned with the edge where the first V-shaped groove and the plane segment of the top surface of the single crystal material intersect, thereby obtaining the bottom coordinates of the first V-shaped groove; The flying cutter disc is rotated to carve a V-shaped groove on the surface of the single crystal material, and the spectral confocal displacement sensor is moved to the bottom of the V-shaped groove to obtain the coordinates of the tool tip, thereby obtaining the relative coordinate relationship between the tool tip and the bottom of the first V-shaped groove; The slitting processing system accurately aligns the tool tip with the bottom of the first V-shaped groove based on the relative coordinate relationship.

6. The ultra-precision composite processing method of a single crystal material V-shaped groove array according to claim 3, characterized in that: In step 3, the rotating spindle drives the flying cutter disc to rotate, and the tool is fed along the V-groove direction by controlling the X-axis. The tool and the V-groove surface interfere with each other, resulting in material removal, and the trimming of the first V-groove is completed; then, the tool is lifted, and the Z-axis is controlled to move the single crystal material in the direction of the rotating spindle axis by a V-groove spacing, and then the tool is dropped to process the second V-groove. This method is followed until all V-grooves are processed.

7. The ultra-precision composite processing method of a single crystal material V-shaped groove array according to claim 2, characterized in that: The tool tip arc radius of the tool is less than or equal to 1 μm, and the obtained V-shaped groove bottom angle arc radius is less than 1 μm.

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