Method for processing glass hemispherical dome by femtosecond laser from both sides

Abstract

This invention belongs to the field of laser processing and relates to a method for processing a glass hemispherical dome using a double-sided femtosecond laser. The method includes the following steps: 1) constructing processing units on the glass hemispherical dome; 2) obtaining the actual pattern trajectory to be processed using parallel projection based on the calculated position coordinates; 3) obtaining the processing path based on the pattern trajectory obtained in step 2); and 4) processing the processing units obtained in step 1) according to the processing path obtained in step 3). This invention provides a glass hemispherical dome double-sided femtosecond laser processing method with high positioning accuracy and effectively improved processing efficiency.

Description

Technical Field

[0001] This invention belongs to the field of laser processing and relates to a laser processing method, particularly a method for processing a glass hemispherical dome with a double-sided femtosecond laser. Background Technology

[0002] Glass is a transparent medium with excellent optical properties. Glass hemispheres play an important role in many fields due to their good optical performance, elegant appearance and wide applicability. The micromachining of glass hemispheres is of great importance in modern science and technology and industry.

[0003] Femtosecond lasers refer to lasers with pulse widths in the femtosecond range. Their extremely short pulse duration allows for highly precise machining within materials. The extremely high peak power of femtosecond laser pulses results in highly concentrated energy deposition within materials, enabling precise removal or modification. Using femtosecond lasers for micromachining of glass hemispheres results in a smaller heat-affected zone, reducing damage to material properties. Simultaneously machining micro / nanostructure patterns (text, lines, polygons, arcs, etc.) on both the inner and outer surfaces of a glass hemisphere, while ensuring overlap of the patterns in the projection direction, requires a machining system with high-precision alignment and positioning capabilities to ensure symmetry and consistency in the machining results. However, maintaining the positioning stability of the hemisphere during double-sided machining remains a challenge, and precise alignment and machining between the two surfaces remains a technical hurdle.

[0004] For example, invention application CN104591549A discloses a method for processing microarrays on glass surfaces using femtosecond laser pulse sequences. This method scans the microarray pattern by the relative motion between the laser focus and the glass material, and forms the microarray structure through a chemical solution reaction, thus enhancing laser etching efficiency. Another example is invention application CN110066104A, which discloses a device and method for double-sided laser processing of glass. This method focuses the laser beam onto the focusing system on the upper and lower sides of the flat glass to be processed by adjusting the positions of mechanical devices and optical elements. The focus point position is monitored by a CCD camera, and double-sided processing is performed using the laser. It is easy to see that existing methods for double-sided laser processing of glass surfaces can only be used for planar processing. They are not suitable for curved surfaces with inconsistent inner and outer surface features. Furthermore, the double-sided positioning method using mechanical devices and optical elements introduces inherent errors in the mechanical devices, resulting in insufficient processing accuracy and large processing errors for micron-level micro-patterns. The method of double-pass single-sided femtosecond laser processing introduces multiple positioning errors, leading to unstable double-sided accuracy and low processing efficiency. Summary of the Invention

[0005] In order to solve the above-mentioned technical problems in the background art, the present invention provides a double-sided femtosecond laser processing method for glass hemispherical domes with high positioning accuracy and effective improvement of processing efficiency.

[0006] To achieve the above objectives, the present invention adopts the following technical solution:

[0007] A method for processing a glass hemispherical dome using a double-sided femtosecond laser, characterized in that the method includes the following steps:

[0008] 1) Construct processing units on the glass hemispherical dome;

[0009] 2) Based on the calculated position coordinates, the actual pattern trajectory to be processed is obtained by parallel projection;

[0010] 3) Obtain the processing path based on the pattern trajectory obtained in step 2);

[0011] 4) Process the processing unit obtained in step 1) according to the processing path obtained in step 3).

[0012] The wall thickness of the glass hemispherical cover mentioned in step 1) above is 2-3mm; the specific implementation method of step 1) is: according to the processing pattern, according to the processing position requirements and the size parameters of the glass hemispherical cover, calculate the position distribution of the processing pattern on the glass hemispherical cover, and obtain the position coordinates.

[0013] The specific implementation method of step 2) above is as follows:

[0014] 2.1) Obtain the theoretical model of the glass hemisphere to be processed;

[0015] 2.2) Project the position coordinates obtained in step 1) onto the theoretical model of the glass hemisphere to be processed obtained in step 2.1) using parallel projection to obtain the actual pattern trajectory to be processed.

[0016] The specific implementation method of step 2.2) above is as follows:

[0017] 2.2.1) Construct several pyramids with the center of the theoretical model of the glass hemisphere as the vertex, and perform Boolean operations between the pyramids and the entire theoretical model of the glass hemisphere to be processed;

[0018] 2.2.2) Extract the Boolean operation results of each pyramid and the theoretical model of the glass hemisphere to be processed to obtain the outline boundary of the pattern that actually needs to be processed;

[0019] 2.2.3) Divide the outline of the actual pattern to be processed obtained in step 2.2.2) on the inner and outer surfaces of the glass hemisphere to obtain inner surface processing data and outer surface processing data; the inner surface processing data is the trajectory of the actual pattern to be processed on the inner surface of the glass hemisphere; the outer surface processing data is the trajectory of the actual pattern to be processed on the outer surface of the glass hemisphere; the trajectory of the actual pattern to be processed on the inner surface of the glass hemisphere and the trajectory of the actual pattern to be processed on the outer surface of the glass hemisphere together constitute the trajectory of the actual pattern to be processed.

[0020] The aforementioned pyramids are triangular pyramids, quadrangular pyramids, or hexagonal pyramids.

[0021] When the aforementioned pyramid is a square pyramid, the method of constructing the square pyramid is as follows:

[0022] a) Establish a three-dimensional coordinate system with the center of the theoretical model of the glass hemisphere to be processed as the origin, where the coordinates of the center of the sphere are O(0,0,0); divide the radius R of the sphere into equal parts according to the side length E of the base of the square pyramid; calculate the Z-coordinate of the divided line segment as follows:

[0023] z i = i*E, i = 1, 2, ..., n

[0024] in:

[0025] n is the floor of R / E; the height used is z. i The plane parallel to the XOY plane intersects with the theoretical model of the glass hemisphere to be processed, resulting in a latitudinal intersection line;

[0026] b) Divide the maximum circumference 2πR of the theoretical model of the glass hemisphere to be processed into equal segments along the circumference according to the side length E of the base of the square pyramid, resulting in a total of 2πR / E segments. Taking the zero-degree direction on the XOY plane as the starting position of the radial direction, intersect the hemisphere with the plane formed by the pole of the theoretical model of the glass hemisphere to be processed, the center point O of the sphere, and the endpoints of the line segments, to obtain the meridional intersection line; the angle corresponding to each line segment after equal division is θ. j :

[0027]

[0028] in:

[0029] m is 2πR / E rounded up, i.e., θ m =360°-(m-1)*θ1, θ m ≤θ1;

[0030] θ1 is the angle corresponding to the first line segment after equal division, i.e., j=1;

[0031] c) Calculate the coordinates of the intersections of all meridians and parallels (x...i,j ,y i,j ,z i );

[0032]

[0033] in:

[0034] R is the radius of the hemisphere;

[0035] φ i =arccos(z i / R), from which the vertex coordinates (x) are calculated. i,j ,y i,j ,z i );

[0036] d) Connect the four vertices of the adjacent contour lines to the center of the sphere to construct a square pyramid; the center of the sphere is the vertex of the pyramid, with coordinates O(0,0,0); the coordinates of the four vertices of the base are a(x...). i+1,i ,y i+1,j ,z i+1 b(x) i+1,j+1 ,y i+1,j+1 ,z i+1 ), c(x) i,j+1 ,y i,j+1 ,z i ), d(x i,j ,y i,j ,z i );

[0037] e) For the portion of the theoretical model of the glass hemisphere to be processed near the pole, the height of this portion is less than or equal to the side length E of the square pyramid; calculate the surface area of ​​the hemisphere near the pole as follows: Based on the laser processing range, the hemisphere near the pole is divided into equal parts from the zero point of the X-axis.

[0038] f) Intersect all the calculated square pyramids with the theoretical model of the glass hemisphere to be processed, and retain all the identical and overlapping parts of the square pyramids and the glass hemisphere.

[0039] The specific implementation method of step 3) above is as follows:

[0040] 3.1) Set the processing order. Based on the center point of the processing unit, sort the pattern trajectory obtained in step 2) according to the latitude and longitude directions;

[0041] 3.2) Start from the pole as the first processing unit;

[0042] 3.3) Process a full row along the latitude direction, with the longitude direction as the zero-degree starting point;

[0043] 3.4) Move from the processing block at the end of the previous line to the nearest processing unit in the adjacent latitude line until all processing units have been traversed.

[0044] The processing sequence in step 3.1) above is S-shaped.

[0045] The rows in step 3.3) above represent all processing units of the same latitude on the theoretical model of the glass hemisphere to be processed.

[0046] The specific implementation of step 3.4) above, which involves moving from the processing block at the end of the previous row to the nearest processing unit in the adjacent latitude, is as follows: after all processing units of the same latitude have been traversed, the traversal begins from the last processing unit in the current latitude processing unit, which has the same longitude but a different latitude.

[0047] The advantages of this invention are:

[0048] This invention provides a method for double-sided femtosecond laser processing of a glass hemispherical dome, comprising: 1) constructing processing units on the glass hemispherical dome; 2) obtaining the actual pattern trajectory to be processed using parallel projection based on the calculated position coordinates; 3) obtaining a processing path based on the pattern trajectory obtained in step 2); and 4) processing the processing units obtained in step 1) according to the processing path obtained in step 3). This invention addresses the challenge of existing curved surface laser processing methods failing to simultaneously meet the requirements of processing efficiency and high processing accuracy at the micrometer level. It proposes a double-sided femtosecond laser processing method for a glass hemispherical dome, addressing the inconsistency between the inner and outer surface features of the hemisphere by simultaneously processing the inner and outer surfaces of the hemispherical curved object with a femtosecond laser. This single positioning reduces the error accumulation and processing time caused by multiple positioning operations in existing methods, ensuring the consistency of processing accuracy between the inner and outer surfaces, making the overall processing more efficient. Simultaneously, precise calculations ensure accurate alignment of each processing point, thereby achieving high-quality processing results. Attached Figure Description

[0049] Figure 1 This is a schematic diagram illustrating the principle of spherical coordinate calculation.

[0050] Figure 2 A schematic diagram of a method for constructing a square pyramid based on intersection points;

[0051] Figure 3 This is a schematic diagram of the spherical segmentation result;

[0052] Figure 4 This is a schematic diagram of Boolean operations on a hemispherical surface.

[0053] Figure 5 A schematic diagram showing the outline boundary obtained by cutting a square pyramid and a hemisphere. Detailed Implementation

[0054] The purpose of this invention is to solve the problem that the patterns etched on the inner and outer surfaces of a glass hemisphere using femtosecond lasers do not completely overlap when viewed along the normal direction (due to the thickness of the sphere, there is a distance between the inner and outer surfaces. When observing, one sees two surfaces of the sphere, rather than a completely overlapping sphere). This invention provides a femtosecond laser processing method for the microstructure of the inner and outer surfaces of an ultrathin glass hemisphere (with a wall thickness of 2-3 mm and a thickness tolerance of ±0.005 mm).

[0055] A method for processing a glass hemispherical dome using double-sided femtosecond laser mainly includes the following steps:

[0056] 1) Constructing processing units on a glass hemispherical dome: Specifically, based on the processing pattern, calculating the positional distribution of the processing pattern on the glass hemisphere to obtain position coordinates; preferably, the calculation method is: based on the processing position requirements and the dimensional parameters of the hemisphere, obtaining the position coordinates of the specific processing pattern on the sphere. This is calculated using the spherical coordinate formula;

[0057] 2) Based on the calculated position coordinates of the processing pattern on the glass hemisphere, the actual pattern trajectory to be processed is calculated using parallel projection; this makes the model (the theoretical model of the glass hemisphere to be processed) and the processing pattern a whole (after projection calculation, all point data fall on the sphere, and are cut and divided into processing units together with the sphere, thus forming a whole); this calculation projects the position coordinates to be processed onto the sphere in parallel, that is, scales the points to be projected onto the sphere proportionally;

[0058] When obtaining the actual pattern trajectory to be processed, it can be done as follows:

[0059] 2.1) Construct several pyramids along the center of the glass hemisphere, and perform Boolean operations on the pyramids and the entire theoretical model of the glass hemisphere to be processed, dividing it into multiple pyramids;

[0060] The pyramids constructed in this step include triangular pyramids, square pyramids, and hexagonal pyramids. Since quadrilaterals can completely cover the surface of a sphere and are of uniform size, no other shapes are needed for assistance. Therefore, this invention uses a square pyramid as an example to illustrate its construction method.

[0061] Specifically, a square pyramid is constructed along the center of the glass hemisphere, with the input being the radius R of the sphere and the side length E of the base of the pyramid to be constructed; further, the method for constructing the square pyramid is as follows:

[0062] Establish a three-dimensional coordinate system with the center of the glass hemisphere as the origin, i.e., the coordinates of the center of the sphere are O(0,0,0); divide the radius R of the sphere into equal parts (radial direction) according to the side length E of the base of the square pyramid; calculate the Z coordinate of the divided line segment as follows:

[0063] z i = i*E, i = 1, 2, ..., n

[0064] Where n is R / E rounded up; using height z i A plane parallel to the XOY plane intersects with the hemisphere, resulting in a latitudinal intersection line.

[0065] Divide the maximum circumference of the hemisphere, 2πR, into equal parts along the circumference according to the side length E of the base of the square pyramid, resulting in a total of 2πR / E segments. Taking the zero-degree direction on the XOY plane as the starting position of the radial direction, intersect the hemisphere with the plane formed by the hemisphere's pole, center point O, and the endpoints of the line segments to obtain the meridional intersection line. The angle corresponding to each line segment after equal division is , where the angle is the angle between the lines connecting the two endpoints of the line segment and the center of the circle.

[0066]

[0067] Where: m is 2πR / E rounded up, i.e., θ m =360°-(m-1)*θ1, θ m ≤θ1; θ1 is the angle corresponding to the first line segment after equal division, i.e., j=1.

[0068] Calculate the coordinates of all intersections of meridians and parallels; for example Figure 1 As shown, according to the formula for calculating spherical coordinates:

[0069]

[0070] in:

[0071] R is the radius of the hemisphere, z i From the latitudinal intersection line, θ j φ is calculated from the meridional intersection line. i =arccos(z i / R), from which the vertex coordinates (x) can be calculated. i,j ,y i,j ,z i ).

[0072] Connect the four vertices of adjacent contour lines to the center of the sphere to construct a square pyramid, such as... Figure 2 As shown; the vertex of the square pyramid is the center of the sphere, with coordinates O(0,0,0); the coordinates of the four vertices of the base are a(x...). i+1,i ,y i+1,j ,z i+1 b(x) i+1,j+1 ,y i+1,j+1 ,z i+1 ), c(x) i,j+1 ,y i,j+1 ,z i ), d(xi,j ,y i,j ,z i ).

[0073] For the part of the sphere near the pole, such as Figure 3 As shown, the part of the sphere near the pole (such as...) Figure 3 The height (distance from the base along the meridian to the pole) of the uppermost part (not forming a square pyramid) shown is less than or equal to the side length E of the square pyramid; calculate its surface area (near the pole in the hemisphere). Divide the hemisphere (near the pole) into equal parts from the zero point of the X-axis according to the laser processing range (such as dividing it into four or eight parts, which is smaller than the processing range. Due to the limitation of the single processing area in laser processing, it is necessary to process it in regions. Dividing it into equal parts is the simplest method of region division).

[0074] The intersection of all calculated square pyramids with the glass hemisphere processing model is calculated, retaining all identical and overlapping portions of the pyramids and the glass hemisphere. The portion of each pyramid cut from the glass hemisphere is extracted, along with its contour boundary (connecting each of the four vertices of the calculated pyramid base pairwise constitutes the contour boundary). Each pyramid's contained portion is divided into inner and outer surfaces. Specifically, for each constructed pyramid, the intersection with the inner and outer surfaces of the hemisphere is calculated, and the distance from the intersection point to the center of the hemisphere determines the inner and outer surfaces; the surface closer to the center is the inner surface. All the data obtained from the pyramid cuts (the cut surfaces are polygons) are divided into inner and outer surfaces, yielding inner and outer surface processing data. The inner surface processing data represents the trajectory of the actual pattern to be processed on the inner surface of the glass hemisphere; the outer surface processing data represents the trajectory of the actual pattern to be processed on the outer surface of the glass hemisphere. The combined trajectory of the actual pattern to be processed on the inner and outer surfaces of the glass hemisphere constitutes the actual pattern trajectory to be processed.

[0075] 3) Calculate the processing path

[0076] 3.1) Set the processing sequence, and sort them according to the latitude and longitude lines based on the center point of the processing unit; the processing sequence can be set to an S-shape:

[0077] 3.2) Start from the pole as the first processing unit;

[0078] 3.3) Process a complete row along the latitudinal direction, with the longitudinal direction as the zero-degree starting point; where a row refers to all processing units with the same latitude on a hemisphere;

[0079] 3.4) Move from the processing block at the end of the previous row to the nearest processing unit in the adjacent latitude line until all processing units have been traversed; the way to move is: after all processing units of the same latitude have been traversed, start traversing from the last processing unit in the current latitude processing unit with the same longitude but different latitude.

[0080] 3.5) Assign the machining data of the inner surface group and the outer surface group to different finishing tools.

[0081] 4) Process the inner and outer surface processing units according to the processing path in step 3).

[0082] For example, based on the processing results, the processing quality can also be inspected. For instance, after processing, the overlap rate of the outline width of the graphic elements on the inner and outer surfaces of the processed pattern is checked; a double-sided linewidth overlap error ≤2μm is considered acceptable; the linewidth of the processed graphic elements is checked to ensure it meets the requirements. If the minimum linewidth is 10μm and the accuracy is ±1μm, the processing requirements are met. The dimensions of the glass hemispherical sample are: outer diameter 145mm, height 50mm, spherical radius 80mm, thickness tolerance ±0.005mm, and wall thickness 2.5~3mm. Processing requirements: double-sided curved superstructure surface units, with overlapping projections of inner and outer micro / nano structure units, and linewidths in the sub-micron to micron range. 1. Double-sided linewidth overlap error ≤2μm; 2. Minimum linewidth 10μm, accuracy ±1μm; 3. Line height requirement ≥3μm.

Claims

1. A method for double-sided femtosecond laser processing of a glass hemispherical dome, characterized in that: The glass hemispherical dome double-sided femtosecond laser processing method includes the following steps: 1) Construct processing units on the glass hemisphere, specifically: calculate the position distribution of the processing pattern on the glass hemisphere based on the processing pattern, processing position requirements, and the size parameters of the glass hemisphere, and obtain the position coordinates; 2) Based on the calculated position coordinates, the actual pattern trajectory to be processed is obtained using parallel projection. Specifically: 2.1) Obtain the theoretical model of the glass hemisphere to be processed; 2.2) Project the position coordinates obtained in step 1) onto the theoretical model of the glass hemisphere to be processed obtained in step 2.1) using parallel projection to obtain the actual pattern trajectory to be processed, specifically: 2.2.1) Construct several pyramids with the center of the theoretical model of the glass hemisphere as the vertex, and perform Boolean operations between the pyramids and the entire theoretical model of the glass hemisphere to be processed; 2.2.2) Extract the Boolean operation results of each pyramid and the theoretical model of the glass hemisphere to be processed to obtain the outline boundary of the pattern that actually needs to be processed; 2.2.3) Divide the outline of the actual pattern to be processed obtained in step 2.2.2) on the inner and outer surfaces of the glass hemisphere to obtain inner surface processing data and outer surface processing data; the inner surface processing data is the trajectory of the actual pattern to be processed on the inner surface of the glass hemisphere; the outer surface processing data is the trajectory of the actual pattern to be processed on the outer surface of the glass hemisphere; the trajectory of the actual pattern to be processed on the inner surface of the glass hemisphere and the trajectory of the actual pattern to be processed on the outer surface of the glass hemisphere together constitute the trajectory of the actual pattern to be processed; 3) Obtain the processing path based on the pattern trajectory obtained in step 2); 4) Process the processing unit obtained in step 1) according to the processing path obtained in step 3).

2. The method for double-sided femtosecond laser processing of a glass hemispherical dome according to claim 1, characterized in that: The wall thickness of the glass hemispherical cover in step 1) is 2-3 mm.

3. The method for double-sided femtosecond laser processing of a glass hemispherical dome according to claim 2, characterized in that: The pyramid is a triangular pyramid, a square pyramid, or a hexagonal pyramid.

4. The method for double-sided femtosecond laser processing of a glass hemispherical dome according to claim 3, characterized in that: When the pyramid is a square pyramid, the method of constructing the square pyramid is as follows: a) Establish a three-dimensional coordinate system with the center of the theoretical model of the glass hemisphere to be processed as the origin, where the coordinates of the center of the sphere are O(0,0,0); divide the radius R of the sphere into equal parts according to the side length E of the base of the square pyramid; calculate the Z-coordinate of the divided line segment as follows: z i =i*E,i=1,2,…,n in: n is the floor of R / E; the height used is z. i The plane parallel to the XOY plane intersects with the theoretical model of the glass hemisphere to be processed, resulting in a latitudinal intersection line; b) Divide the maximum circumference 2πR of the theoretical model of the glass hemisphere to be processed into equal segments along the circumference according to the side length E of the base of the square pyramid, resulting in a total of 2πR / E segments. Taking the zero-degree direction on the XOY plane as the starting position of the radial direction, intersect the hemisphere with the plane formed by the pole of the theoretical model of the glass hemisphere to be processed, the center point O of the sphere, and the endpoints of the line segments, to obtain the meridional intersection line; the angle corresponding to each line segment after equal division is θ. j : in: m is 2πR / E rounded up, i.e., θ m =360°-(m-1)*θ1, θ m ≤θ1; θ1 is the angle corresponding to the first line segment after equal division, i.e., j=1; c) Calculate the coordinates of the intersections of all meridians and parallels (x... i,j ,y i,j ,z i ); in: R is the radius of the hemisphere; φ i =arccos(z i / R), from which the vertex coordinates (x) are calculated. i,j ,y i,j ,z i ); d) Connect the four vertices of the adjacent contour lines to the center of the sphere to construct a square pyramid; the center of the sphere is the vertex of the pyramid, with coordinates O(0,0,0); the coordinates of the four vertices of the base are a(x...). i+1,i ,y i+1,j ,z i+1 b(x) i+1,j+1 ,y i+1,j+1 ,z i+1 ), c(x) i,j+1 ,y i,j+1 ,z i ), d(x i,j ,y i,j ,z i ); e) For the portion of the theoretical model of the glass hemisphere to be processed near the pole, the height of this portion is less than or equal to the side length E of the square pyramid; calculate the surface area of ​​the hemisphere near the pole as follows: Based on the laser processing range, the hemisphere near the pole is divided into equal parts from the zero point of the X-axis. f) Intersect all the calculated square pyramids with the theoretical model of the glass hemisphere to be processed, and retain all the identical and overlapping parts of the square pyramids and the glass hemisphere.

5. The method for double-sided femtosecond laser processing of a glass hemispherical dome according to claim 4, characterized in that: The specific implementation method of step 3) is as follows: 3.1) Set the processing order. Based on the center point of the processing unit, sort the pattern trajectory obtained in step 2) according to the latitude and longitude directions; 3.2) Start from the pole as the first processing unit; 3.3) Process a full row along the latitude direction, with the longitude direction as the zero-degree starting point; 3.4) Move from the processing block at the end of the previous line to the nearest processing unit in the adjacent latitude line until all processing units have been traversed.

6. The method for double-sided femtosecond laser processing of a glass hemispherical dome according to claim 5, characterized in that: The processing sequence in step 3.1) is S-shaped.

7. The method for double-sided femtosecond laser processing of a glass hemispherical dome according to claim 6, characterized in that: The rows in step 3.3) are all processing units of the same latitude on the theoretical model of the glass hemisphere to be processed.

8. The method for double-sided femtosecond laser processing of a glass hemispherical dome according to claim 7, characterized in that: The specific implementation of step 3.4) of moving from the processing block at the end of the previous row to the nearest processing unit in the adjacent latitude is as follows: after all processing units of the same latitude have been traversed, the traversal is performed from the last processing unit in the current latitude processing unit that has the same longitude but a different latitude.

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