A femtosecond laser parallel processing method with dynamic focus array based on area planning

Abstract

The present invention provides a dynamic focal spot array femtosecond laser parallel processing method based on area planning, step 1: convert the pattern to be processed into a binary image; step 2: divide the image to be processed into m sub-areas to be processed; step 3: obtain a focal spot array image sequence; step 4: obtain a corresponding computer-generated hologram sequence; step 5: calculate the loading time of each computer-generated hologram in the computer-generated hologram sequence on the spatial light modulator, and make the computer-generated hologram sequence into a video stream according to the loading time, and load it onto the spatial light modulator; step 6: form a dynamic sequence of the focal spot array, and form the pattern to be processed inside or on the surface of the material. The present invention divides the area to be processed into multiple areas with the same number of scanning points required for processing by area planning of the area to be processed, and then performs dynamic focal spot generation and scanning on all areas, so as to realize uniform parallel processing of complex patterns.

Description

Technical Field

[0001] The invention relates to the field of femtosecond laser processing, and in particular to a dynamic focus spot array femtosecond laser parallel processing method based on area planning. Background Art

[0002] Femtosecond laser processing has broad application prospects in many fields due to its advantages of "cold" processing, wide range of processing materials, and high processing precision. However, due to the shortcomings of femtosecond laser point scanning processing such as low efficiency and slow speed, people have invented a variety of femtosecond laser parallel processing methods, such as multi-beam coherence, multi-focal spot array, holographic calculation map, etc. Among them, multi-beam coherence parallel processing can generally only process periodic ordered patterns, and is powerless for processing arbitrary patterns; multi-focal spot array parallel processing needs to process patterns according to the trajectory of the focal spot, and the trajectory calculation of each focal spot is complex, making it difficult to realize complex pattern processing; for the pattern composed of multiple focal spots obtained by holographic calculation map, different patterns are composed of different numbers of focal spots. Without changing the energy of the incident femtosecond laser, this results in different energies of each focal spot of different patterns, affecting the processing effect. Summary of the invention

[0003] The existing femtosecond laser parallel processing methods cannot simultaneously solve the problem of uniform parallel processing of complex patterns. The purpose of the present invention is to provide a dynamic focal spot array femtosecond laser parallel processing method based on area planning. By performing area planning on the processing area, the number of focal spots of the dynamic focal spot array is made consistent each time, thereby achieving uniform parallel processing of complex patterns.

[0004] To achieve the above object, the present invention provides the following technical solution: a dynamic focus array femtosecond laser parallel processing method based on area planning, comprising the following steps:

[0005] Step 1: Convert the pattern to be processed into a binary image with grayscale values ​​of only 1 and 0. Assume that the grayscale value of the position to be processed is 1, and the grayscale value of the gap position of the pattern to be processed that does not need to be processed is 0; and calculate the number of pixels with a grayscale value of 1 as an integer N;

[0006] Step 2: Use clustering algorithm to plan the area of ​​the processing area and divide the image to be processed into m (m is an integer) sub-areas to be processed (A 1 ,A 2 ,…,A m ), where all m sub-areas to be processed (A 1 ,A 2 ,…,A m ) contain c processed pixels with a gray value of 1, where c = N / m;

[0007] Step 3: For all m sub-regions to be processed, one pixel with a gray value of 1 is sequentially extracted from the c processed pixels with a gray value of 1 to form a focal spot array (P 1 ,P 2 ,…,P m ) i ; For all the pixels in the m sub-regions to be processed, a sequence of focal spot array images [(P 1 ,P 2 ,…,P m ) 1 ,(P 1 ,P 2 ,…,P m ) 2 ,…,(P 1 ,P 2 ,…,P m ) c ];

[0008] Step 4: Convert the focal spot array sequence [(P 1 ,P 2 ,…,P m ) 1 ,(P 1 ,P 2 ,…,P m ) 2 ,…,(P 1 ,P 2 ,…,P m ) c Each focal spot array in ] is used as a laser focal spot distribution. Through inverse Fourier transform, GS algorithm and other methods, the corresponding pure phase or complex amplitude CGH is calculated to obtain the corresponding CGH sequence [CGH 1 ,CGH 2 ,…,CGH c ];

[0009] Step 5: Calculate the CGH sequence [CGH 1 ,CGH 2 ,…,GCH c Each CGH in ] i The loading time (t 1 ,t 2 ,…,t c ), and make the computational hologram sequence into a video stream based on the loading time [CGH 1 ·t 1 ,CGH 2 ·t 2 ,…,CGH c ·tc ] and loaded onto a spatial light modulator;

[0010] Step 6: The incident femtosecond laser is irradiated onto the spatial light modulator and then focused by the objective lens to form a dynamic sequence of focal spot arrays (s 1 ,s 2 ,…,s c ), the dynamic sequence of the focal spot array interacts with the material to form the desired processing pattern inside or on the surface of the material.

[0011] Compared with the prior art, the present invention has the following beneficial effects:

[0012] The present invention divides the area to be processed into a plurality of areas with the same number of required processing point scans by area planning of the area to be processed, and then dynamically generates and scans the focal spots in all the areas to achieve uniform parallel processing of complex patterns. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 It is a processing flow chart of the present invention;

[0014] Figure 2 The pattern to be processed;

[0015] Figure 3 is a binary image;

[0016] Figure 4 For Figure 3 The schematic diagram obtained after sub-region division, different sub-regions are represented by different grayscale values;

[0017] Figure 5 is the focal spot array pattern;

[0018] Figure 6 For computational holograms;

[0019] Figure 7 is a dynamic sequence diagram of the formed focal spot array;

[0020] Figure 8 To form the desired processing pattern. DETAILED DESCRIPTION

[0021] In order to make the purpose, technical solution and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. The specific embodiments described here are only used to explain the technical solution of the present invention and are not limited to the present invention.

[0022] The present invention provides a dynamic focus array femtosecond laser parallel processing method based on area planning, and the processing flow is as follows: Figure 1 As shown, the following steps are included:

[0023] Step 1: Place the pattern you want to process ( Figure 2 ) becomes a binary image with grayscale values ​​of only 1 and 0 ( Figure 3 ), assuming that the gray value of the position to be processed is 1, and the gray value of the gap position of the pattern to be processed that does not need to be processed is 0; and the number of pixels with a gray value of 1 is calculated to be an integer N.

[0024] Step 2: Use clustering algorithm to plan the area of ​​the processing area and divide the binary image to be processed into m (m is an integer) sub-areas to be processed (A 1 ,A 2 ,…,A m ), where all m sub-areas to be processed (A 1 ,A 2 ,…,A m ) contain c processed pixels with a gray value of 1, where c = N / m; the steps for dividing the m sub-areas to be processed are:

[0025] (1) Scan point by point, first scan row by row from top to bottom, then scan the points on each row from left to right, find the point with gray value 1, and save its position in the scanning order. After scanning, select the first point with gray value 1 as the first sub-region to generate seed point S1, whose coordinates are (x 1 ,y 1 );

[0026] (2) Taking S1 as the starting point, calculate the distance from the neighboring pixels of S1 to S1 And according to the distance d 1 Sort by d 1 The nearest (c-1) points are selected to form a sub-area, which is divided into the first sub-area A to be processed. 1 ; Divide the image to be processed into sub-areas A to be processed 1 The gray value becomes 0.

[0027] (3) Then select the first point among the remaining points with a grayscale value of 1 as the second sub-region seed point S2, take S2 ​​as the starting point, and calculate the distance from the neighboring pixels of S2 to S2 And according to the distance d 2 Sort by d 2 Sort by, select the closest (c-1) points to form sub-area A 2 , divided into the first sub-area A to be processed 2 ; Divide the image to be processed into sub-areas A to be processed 2 The gray value becomes 0.

[0028] (4) The other sub-regions to be processed are divided in accordance with steps (1) to (3) in sequence. If different sub-regions are filled with different grayscale values, the following is obtained after the sub-region division is completed: Figure 4 Schematic diagram of sub-area division shown.

[0029] Step 3: For all m sub-regions to be processed, extract a pixel with a gray value of 1 from the c processed pixels with a gray value of 1 in sequence to form Figure 5 The focal spot array shown (P 1 , P 2 , ..., P m ) i ; For all pixels in the m sub-areas to be processed, a sequence of focal spot array images can be obtained

[0030] [(P 1 , P 2 , ..., P m ) 1 , (P 1 , P 2 , ..., P m ) 2 , ..., (P 1 , P 2 , ..., P m ) c ].

[0031] Step 4: Sequence the focal spot pattern

[0032] [(P 1 , P 2 , ..., P m ) 1 , (P 1 , P 2 , ..., P m ) 2 , ..., (P 1 , P 2 , ..., P m ) c Each focal spot array in ] is used as a laser focal spot distribution, and its corresponding pure phase or complex amplitude computational hologram is calculated by inverse Fourier transform, GS algorithm and other methods ( Figure 6 As shown), the corresponding CGH sequence is obtained. 1 , CGH 2 , ..., CGH c ].

[0033] Step 5: Calculate the CGH sequence [CGH 1 , CGH 2 , ..., CGHc Each CGH in ] i The loading time (t 1 , t 2 , ..., t c ), and make the computational hologram sequence into a video stream based on the loading time [CGH 1 ·t 1 , CGH 2 ·t 2 , ..., CGH c ·t c ] and loaded onto the spatial light modulator.

[0034] Step 6: The incident femtosecond laser is irradiated onto the spatial light modulator and then focused by the objective lens to form Figure 7 The dynamic sequence of the focal spot array shown (s 1 ,s 2 , ..., s c ), the dynamic sequence of the focal spot array interacts with the material to form the desired processing pattern inside or on the surface of the material ( Figure 8 shown).

[0035] The above only expresses the preferred embodiments of the present invention, and the description is relatively specific and detailed, but it cannot be understood as limiting the scope of the patent of the present invention. It should be pointed out that for ordinary technicians in this field, without departing from the concept of the present invention, several modifications, improvements and substitutions can be made, which all belong to the protection scope of the present invention. Therefore, the protection scope of the patent of the present invention shall be based on the attached claims.

Claims

1. A femtosecond laser parallel processing method with dynamic focus array based on area planning. It is characterized by: The following steps are involved: Step 1: Convert the pattern to be processed into a binary image with grayscale values ​​of only 1 and 0. Assume that the grayscale value of the position to be processed is 1, and the grayscale value of the gap position of the pattern to be processed that does not need to be processed is 0; and calculate the number of pixels with a grayscale value of 1 as an integer N; Step 2: Use clustering algorithm to plan the area of ​​the processing area and divide the image to be processed into m sub-areas to be processed (A 1 , A 2 , ..., A m ), m is an integer, where all m sub-areas to be processed (A 1 , A 2 , ..., A m ) contain c processed pixels with a gray value of 1, where c = N / m; Step 3: For all m sub-regions to be processed, one pixel with a gray value of 1 is sequentially extracted from the c processed pixels with a gray value of 1 to form a focal spot array (P 1 , P 2 , ..., P m ) i ; For all the pixels in the m sub-areas to be processed, obtain the focus spot array sequence [(P 1 , P 2 , ..., P m ) 1 , (P 1 , P 2 , ..., P m ) 2 , ..., (P 1 , P 2 , ..., P m ) c ]; Step 4: Convert the focal spot array sequence [(P 1 , P 2 , ..., P m ) 1 , (P 1 , P 2 , ..., P m ) 2 , ..., (P 1 , P 2 , ..., P m ) c Each focal spot array in ] is used as a laser focal spot distribution, and its corresponding pure phase or complex amplitude CGH is calculated to obtain the corresponding CGH sequence [CGH 1 , CGH 2 , ..., CGH c ]; Step 5: Calculate the CGH sequence [CGH 1 , CGH 2 , ..., CGH c Each CGH in ] i The loading time (t 1 , t 2 , ..., t c ), and make the computational hologram sequence into a video stream based on the loading time [CGH 1 ·t 1 , CGH 2 ·t 2 , ..., CGH c ·t c ] and loaded onto a spatial light modulator; Step 6: The incident femtosecond laser is irradiated onto the spatial light modulator and then focused by the objective lens to form a dynamic sequence of focal spot arrays (s 1 ,s 2 , ..., s c ), the dynamic sequence of the focal spot array interacts with the material to form the desired processing pattern inside or on the surface of the material.

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