Split-beam multi-focus ultrafast laser processing device and method

Abstract

The invention discloses a beam-splitting multi-focus ultrafast laser processing device and method, and relates to the field of transparent hard and brittle material laser cutting, and the beam-splitting multi-focus ultrafast laser processing device comprises an ultrafast laser, a first beam splitter, a first dichroscope, a first diaphragm, a reflector, a second dichroscope, a second diaphragm, a first focusing lens group and a second focusing lens group; laser emitted by the ultrafast laser is divided into transmission light and reflection light with equal energy under the first beam splitter, and the transmission light penetrates through the first beam splitter, is reflected by the first dichroscope, penetrates through the first diaphragm and reaches the first focusing lens group to form a first processing light path; the reflected light is reflected by the first beam splitter to the reflector, then passes through the reflector to the second dichroscope, and then is reflected to pass through the second diaphragm to form a second processing light path by the second focusing lens group; a sample piece is arranged on the six-degree-of-freedom translation platform, and the six-degree-of-freedom translation platform drives the sample piece to move between the first focusing lens group and the second focusing lens group; and the electric control translation stage drives the second focusing lens group to move. And the purpose of efficiently cutting the large-thickness transparent material is achieved.

Description

Technical Field

[0001] The invention relates to an ultrafast laser processing optical path building device, and belongs to the field of transparent hard and brittle material laser cutting. Background Art

[0002] Optoelectronic payloads are key payloads that affect the performance of high-precision optical detection and optoelectronic guided weapons in space. Optical components determine the performance of optoelectronic payloads. Transparent hard and brittle materials are widely used in optical components, and their high-quality and high-precision cutting has always been a difficult problem in the field of precision manufacturing. Traditional mechanical processing technology usually requires coolant cooling, mechanical breaking, and subsequent grinding, which seriously affects material properties and processing accuracy. Femtosecond lasers have the advantages of high precision and cold processing due to their strong nonlinear effects and ultra-short pulse width. At present, the high-quality micro-nano processing technology of femtosecond lasers for ultra-thin transparent materials has been mature, but the plasma cloud formed by the interaction between the focused beam and the material during the processing of ordinary femtosecond laser Gaussian beams hinders the further absorption of energy and limits the depth of processing. The researchers stretched the Gaussian beam through spatial shaping to form a Bessel beam. Using this method, the processing depth was significantly increased to tens of microns. However, as the depth increases further, the number of scans increases accordingly, and the uneven energy absorption and heat accumulation in the thickness direction hinder the improvement of processing thickness and efficiency and affect the processing quality. The development of a new simple and easy-to-adjust cutting optical path device based on femtosecond laser spatial shaping has engineering application significance. Summary of the invention

[0003] The technical problem solved by the present application is: to overcome the deficiencies of the prior art and to provide a split-beam multi-focus ultrafast laser processing device to achieve the purpose of efficient cutting of thick transparent materials.

[0004] The technical solutions provided by this application are as follows:

[0005] A beam splitting multi-focus ultrafast laser processing device comprises an ultrafast laser, a first beam splitter, a first dichroic mirror, a first aperture, a reflector, a second dichroic mirror, a second aperture, a first focusing lens group, a second focusing lens group, a six-degree-of-freedom translation stage and an electrically controlled translation stage; laser light emitted by the ultrafast laser is divided into transmitted light and reflected light of equal energy under the first beam splitter, the transmitted light passes through the first beam splitter, is reflected by the first dichroic mirror, passes through the first aperture to the first focusing lens group, and the light beam is focused to form a first processing light path with a long focal depth; the reflected light is reflected by the first beam splitter to the reflector, then passes through the reflector to the second dichroic mirror, and then reflects through the second aperture to be focused by the second focusing lens group to form a second processing light path; a sample is arranged on the six-degree-of-freedom translation stage, and the six-degree-of-freedom translation stage is used to drive the sample to move between the first focusing lens group and the second focusing lens group; the electrically controlled translation stage drives the second focusing lens group to move.

[0006] It also includes a second beam splitter, a first CCD and a light source. Part of the white illumination light emitted by the light source is reflected by the sample to be processed to form light source reflected light, and part of it passes through the sample to be processed to form light source transmitted light. After the light source reflected light passes through the first focusing lens group and the first dichroic mirror, it is reflected by the second beam splitter to the first CCD, and the real-time processing status of the surface of the sample to be processed facing the light source is obtained on the first CCD.

[0007] It also includes a third beam splitter and a second CCD. After the light transmitted by the light source passes through the second aperture and the second dichroic mirror, it is reflected by the third beam splitter to the second CCD, and the real-time processing status of the surface of the sample to be processed on the side away from the light source is obtained on the second CCD.

[0008] It also includes a computer system, which is connected to the ultrafast laser and is used to control the opening and closing of the ultrafast laser.

[0009] The computer system is also connected to the electric-controlled translation stage, the six-degree-of-freedom translation stage and the CCD observation system. The computer system is used to obtain the observation results of the first CCD and the second CCD, and according to the observation results, control the electric-controlled translation stage and the six-degree-of-freedom translation stage to drive the second focusing lens group and the sample to move, adjust the processing depth of the sample, and control the two sides of the sample to be processed at the specified processing depth by the focused light beam at the same time.

[0010] The first focusing lens group and the second focusing lens group have the same structure, both including lens L1 and focusing lens L2. The high energy field at the center of the Gaussian beam is dispersed by lens L1 to achieve light field homogenization, and then the focal depth is lengthened by focusing lens L2 to form a Bessel-like beam.

[0011] A split-beam multi-focus ultrafast laser processing method, using any of the split-beam multi-focus ultrafast laser processing devices described above for processing, comprising:

[0012] Perform optical path calibration;

[0013] After the optical path is calibrated, the sample is moved between the first focusing lens group and the second focusing lens group by the six-degree-of-freedom translation stage. The computer system controls the ultrafast laser to turn on, and the computer system obtains the observation results of the first CCD and the second CCD. According to the observation results, the electric-controlled translation stage and the six-degree-of-freedom translation stage are controlled to move the second focusing lens group and the sample, and the processing depth of the sample is adjusted so that the two sides of the sample are processed at the specified processing depth by the focused light beam at the same time.

[0014] The optical path calibration comprises: driving the sample to move to a position not between the first focusing lens group and the second focusing lens group by a six-degree-of-freedom translation stage; turning on the ultrafast laser mechanical switch, so that the laser passes through the first beam splitter and is semi-transmitted and semi-reflected to be divided into transmitted light and reflected light with the same energy, adjusting the angles of the first beam splitter and the first dichroic mirror so that the transmitted light passes through the first aperture and the second aperture to achieve beam calibration; adjusting the angles of the reflector and the second dichroic mirror so that the reflected light passes through the reflector and the second dichroic mirror in sequence and passes through the first aperture and the second aperture at the same time to achieve calibration; after calibration, installing the first focusing lens group and the second focusing lens group after calibration, so that the transmitted light finally passes through the first focusing lens group to form a first processing optical path, and the reflected light finally passes through the second focusing lens group to form a second processing optical path.

[0015] In summary, this application at least includes the following beneficial technical effects:

[0016] (1) The device of the present invention has controllable coupling characteristics between laser energy and material under the same experimental conditions, a smaller heat-affected zone, a smaller temperature difference in the thickness direction, and smaller thermal stress and residual stress, thereby having higher processing quality and precision.

[0017] (2) The device of the present invention realizes dual-beam processing using a single laser and increases the focal depth through spatial shaping, thereby increasing the processing efficiency by more than two times.

[0018] (3) The device of the present invention coordinately controls the feeding of the two beams of light path through the electric control platform and the six-degree-of-freedom translation stage, ensures the processing depth of the two focused light filaments, and realizes flexible adjustment of the processing line. The same group of aperture calibration ensures the coaxiality of the two processing light paths, thereby realizing collimation processing.

[0019] (4) The device of the present invention has no special requirements for the environment, is simple to build, has flexible switching between single and double beam optical paths, is highly efficient, and has low cost. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 It is a schematic diagram of the optical path of a split-beam multi-focus ultrafast laser processing device, wherein the y-axis is the focused laser processing depth direction.

[0021] Figure 2 Schematic diagram of beam shaping by focusing lens group. a and b are schematic diagrams of light filaments before and after shaping, respectively.

[0022] Figure 3 Schematic diagram of split-beam multi-focus ultrafast laser parallel processing.

[0023] Explanation of the accompanying drawings: 1-ultrafast laser; 2-first beam splitter; 3-first dichroic mirror; 4-first aperture; 5-second beam splitter; 6-first CCD; 7-light source; 8-reflector; 9-second dichroic mirror; 10-third beam splitter; 11-second CCD; 12-second aperture; 13-first focusing lens group; 14-second focusing lens group; 15-electrically controlled translation stage; 16-six-degree-of-freedom translation stage; 17-sample; 18-computer system. DETAILED DESCRIPTION

[0024] In order to make the objectives, technical solutions and advantages of the present invention more clear, the embodiments disclosed in the present invention will be further described in detail below with reference to the accompanying drawings.

[0025] The embodiment of the present application discloses a split-beam multi-focus ultrafast laser processing device.

[0026] like Figure 1 As shown, the ultrafast laser processing device with split beam and multiple focal points of the present invention comprises an ultrafast laser 1, a first beam splitter 2, a first dichroic mirror 3, a first aperture 4, a second beam splitter 5, a first CCD 6, a light source 7, a reflector 8, a second dichroic mirror 9, a third beam splitter 10, a second CCD 11, a second aperture 12, a first focusing lens group 13, a second focusing lens group 14, an electric control translation stage 15, a six-degree-of-freedom translation stage 16, a sample 17 and a computer system 18. The ultrafast laser 1 is a femtosecond laser. The sample 17 is a transparent sample. The sample to be processed is placed on the six-degree-of-freedom translation stage 16 to control the normal feeding of the focused beam and the processing path.

[0027] Ultrafast laser pulses are generated by a high repetition rate ultrafast laser 1 , and the shutter switch of the ultrafast laser 1 is controlled by a computer system 18 .

[0028] First processing optical path:

[0029] The laser emitted by the ultrafast laser 1 is divided into two beams of equal energy under the first beam splitter 2, one of which passes through the first beam splitter 2, is reflected by the first dichroic mirror 3, passes through the first aperture 4 to the first focusing lens group 13, and the beam is focused to form a first processing optical path with a long focal depth.

[0030] Second processing optical path:

[0031] Another beam of light is reflected by the first beam splitter 2 to the reflector 8, and then to the second dichroic mirror 9 via the reflector 8, and then reflected through the second aperture 12 and focused by the second focusing lens group 14 to form a second processing light path.

[0032] The first aperture 4 and the second aperture 12 are installed in the same plane parallel to the y-axis to ensure that they are collinear. The two light paths are blocked in sequence, and the alignment of the processing light paths is calibrated by the first aperture 4 and the second aperture 12 respectively to ensure the overlap in spatial position, thereby achieving coaxial processing of the two processing light paths.

[0033] The second focusing lens group 14 of the second processing light path is installed on the electric control translation stage 15, provides y-axis movement, and cooperates with the electric control translation stage 15 to control the feeding of the second processing light path. That is, the electric control translation stage 15 is used to drive the second focusing lens group 14 to move, so as to control the position of the second focusing lens group 14 so that the focus of the second focusing lens group 14 is focused on different depths on one side of the sample 17; through the coordinated movement of the electric control translation stage 15 and the six-degree-of-freedom translation stage 16, the focus of the first focusing lens group 13 and the second focusing lens group 14 is focused on different depths on both sides of the sample 17, so as to improve the processing quality and accuracy, such as Figure 3 And through the coordinated movement of the electric control translation stage 15 and the six-degree-of-freedom translation stage 16, the processing trajectories of the two processing light paths are controlled simultaneously, ensuring the path consistency of the double-sided processing of the transparent material, and any pattern processing can be performed.

[0034] The light source 7 illuminates the sample 17 to be processed from the left through the optical element. The white illumination light emitted by the light source 7 is partially reflected by the sample 17 to be processed to form the light source reflected light, and partially passes through the sample 17 to be processed to form the light source transmitted light. After passing through the first focusing lens group 13 and the first dichroic mirror 3, part of the light source reflected light of the sample 17 is reflected by the second beam splitter 5 to the first CCD6, forming a reflective real-time processing monitoring; after passing through the second aperture 12 and the second dichroic mirror 9, part of the light source transmitted light of the sample 17 is reflected by the third beam splitter 10 to the second CCD11, forming a transmissive real-time processing monitoring. The reflected light and the transmitted light formed by the second beam splitter 5 and the third beam splitter 10 are imaged in the observation systems of the first CCD6 and the second CCD11, respectively, which can assist in confirming the position of the focused beam.

[0035] The computer system 18 is connected to control the CCD imaging unit (including the first CCD6 and the second CCD11), the six-degree-of-freedom translation stage 16 and the ultrafast laser 1, and integrates observation, processing path control and laser parameter regulation. Specifically, the computer system 18 is connected to the ultrafast laser 1, the electric-controlled translation stage 15, the six-degree-of-freedom translation stage 16 and the CCD observation system. The computer system 18 is used to control the opening and closing of the ultrafast laser 1. The computer system 18 is used to obtain the observation results of the first CCD6 and the second CCD11, and according to the observation results, control the electric-controlled translation stage 15 and the six-degree-of-freedom translation stage 16 to drive the second focusing lens group 14 and the sample 17 to move, adjust the processing depth of the sample 17, and ensure that the two sides of the sample 17 are processed by the focused light beam at the specified processing depth at the same time.

[0036] The first focusing lens group 13 and the second focusing lens group 14 have the same structure, both including lens L1 and focusing lens L2. The focusing lens group disperses the central high energy field of the Gaussian beam through lens L1 to achieve light field homogenization, and then extends the focal depth through focusing lens L2 to form a Bessel-like beam. The principle diagram is shown in FIG. Figure 2 As shown in FIG. 1 , the structure of the focusing lens group lengthens the focal depth and increases the processing speed.

[0037] A processing method based on the above-mentioned split-beam multi-focus ultrafast laser processing device includes:

[0038] First, the optical path is calibrated: the sample 17 is moved to a position not between the first focusing lens group 13 and the second focusing lens group 14 by the six-degree-of-freedom translation stage 16; the mechanical switch of the ultrafast laser 1 is turned on, and the laser passes through the first beam splitter 2 and is semi-transmissive and semi-reflective to be divided into transmitted light and reflected light with the same energy, and the angles of the first beam splitter 2 and the first dichroic mirror 3 are adjusted so that the transmitted light passes through the first aperture 4 and the second aperture 12 to achieve beam calibration; the angles of the reflector 8 and the second dichroic mirror 9 are adjusted so that the reflected light passes through the reflector 8 and the second dichroic mirror 9 in sequence and then passes through the first aperture 4 and the second aperture 12 at the same time to achieve calibration; after calibration, the first focusing lens group 13 and the second focusing lens group 14 are installed after calibration, and the transmitted light finally passes through the first focusing lens group 13 to form the first processing optical path, and the reflected light finally passes through the second focusing lens group 14 to form the second processing optical path.

[0039] Processing: The sample 17 is moved between the first focusing lens group 13 and the second focusing lens group 14 by the six-degree-of-freedom translation stage 16, and the computer system 18 controls the ultrafast laser 1 to start. The computer system 18 obtains the observation results of the first CCD6 and the second CCD11, and according to the observation results, controls the electric-controlled translation stage 15 and the six-degree-of-freedom translation stage 16 to drive the second focusing lens group 14 and the sample 17 to move, and adjusts the processing depth of the sample 17 so that the two sides of the sample 17 are processed by the focused light beam at the specified processing depth at the same time.

[0040] The device of the present invention has strong configuration flexibility. The two processing optical paths can be processed independently to form two production lines. The Michelson interferometer can be used to replace the first beam splitter 2 to transform it into a double-pulse processing optical path. At the same time, the light beam is focused inside the material, and the nonlinear absorption characteristics are used to perform three-dimensional processing.

[0041] The contents not described in detail in this application specification belong to the common knowledge of those skilled in the art.

[0042] The present application is described in detail above in conjunction with specific implementation methods and exemplary examples, but these descriptions cannot be understood as limiting the present application. Those skilled in the art understand that, without departing from the spirit and scope of the present application, a variety of equivalent replacements, modifications or improvements can be made to the technical solution of the present application and its implementation methods, all of which fall within the scope of the present application. The scope of protection of the present application shall be subject to the attached claims.

Claims

1. A split-beam multi-focus ultrafast laser processing device, characterized in that: It comprises an ultrafast laser (1), a first beam splitter (2), a first dichroic mirror (3), a first aperture (4), a reflecting mirror (8), a second dichroic mirror (9), a second aperture (12), a first focusing lens group (13), a second focusing lens group (14), an electrically controlled translation stage (15) and a six-degree-of-freedom translation stage (16); Laser light emitted by an ultrafast laser (1) is divided into transmitted light and reflected light of equal energy under a first beam splitter (2); the transmitted light passes through the first beam splitter (2), is reflected by a first dichroic mirror (3), passes through a first aperture (4) to a first focusing lens group (13), and the light beam is focused to form a first processing optical path with a long focal depth; The reflected light is reflected by the first beam splitter (2) to the reflector (8), then passes through the reflector (8) to the second dichroic mirror (9), and then reflects through the second aperture (12) and is focused by the second focusing lens group (14) to form a second processing light path; The sample (17) is arranged on a six-degree-of-freedom translation platform (16), and the six-degree-of-freedom translation platform (16) is used to drive the sample (17) to move between a first focusing lens group (13) and a second focusing lens group (14); the electric-controlled translation platform (15) drives the second focusing lens group (14) to move.

2. The split-beam multi-focus ultrafast laser processing device according to claim 1, characterized in that: The invention also comprises a second beam splitter (5), a first CCD (6) and a light source (7); part of the white illumination light emitted by the light source (7) is reflected by the sample to be processed (17) to form light source reflected light, and part of the white illumination light passes through the sample to be processed (17) to form light source transmitted light; after the light source reflected light passes through the first focusing lens group (13) and the first dichroic mirror (3), it is reflected by the second beam splitter (5) to the first CCD (6); and the first CCD (6) obtains the real-time processing status of the surface of the sample to be processed (17) on the side facing the light source (7).

3. The split-beam multi-focus ultrafast laser processing device according to claim 2, characterized in that: The invention also comprises a third beam splitter (10) and a second CCD (11). After the light transmitted by the light source passes through the second aperture (12) and the second dichroic mirror (9), it is reflected by the third beam splitter (10) to the second CCD (11). The second CCD (11) obtains the real-time processing status of the surface of the side of the sample (17) to be processed that is away from the light source (7).

4. The split-beam multi-focus ultrafast laser processing device according to claim 3, characterized in that: The invention also comprises a computer system (18), which is connected to the ultrafast laser (1), and the computer system (18) is used to control the opening and closing of the ultrafast laser (1).

5. The split-beam multi-focus ultrafast laser processing device according to claim 4, characterized in that: The computer system (18) is also connected to the electric-controlled translation stage (15), the six-degree-of-freedom translation stage (16) and the CCD observation system. The computer system (18) is used to obtain the observation results of the first CCD (6) and the second CCD (11), and according to the observation results, control the electric-controlled translation stage (15) and the six-degree-of-freedom translation stage (16) to drive the second focusing lens group (14) and the sample (17) to move, adjust the processing depth of the sample (17), and control the two sides of the sample (17) to be processed at the specified processing depth by the focused light beam at the same time.

6. The split-beam multi-focus ultrafast laser processing device according to claim 1, characterized in that: The first focusing lens group (13) and the second focusing lens group (14) have the same structure, both comprising a lens L1 and a focusing lens L2. The high energy field at the center of the Gaussian light beam is dispersed by the lens L1 to achieve light field homogenization, and then the focal depth is lengthened by the focusing lens L2 to form a Bessel-like light beam.

7. A split-beam multi-focus ultrafast laser processing method, characterized in that: Processing is performed using a split-beam multi-focus ultrafast laser processing device as described in any one of claims 1 to 6, comprising: Perform optical path calibration; After the optical path is calibrated, the sample (17) is moved between the first focusing lens group (13) and the second focusing lens group (14) by a six-degree-of-freedom translation stage (16), the computer system (18) controls the ultrafast laser (1) to start, and the computer system (18) obtains the observation results of the first CCD (6) and the second CCD (11). According to the observation results, the electric control translation stage (15) and the six-degree-of-freedom translation stage (16) are controlled to drive the second focusing lens group (14) and the sample (17) to move, and the processing depth of the sample (17) is adjusted, so that the two sides of the sample (17) are processed by the focused light beam at the specified processing depth at the same time.

8. The method for ultrafast laser processing with split beam and multiple focal points according to claim 7, characterized in that: The optical path calibration comprises: The sample (17) is driven to move to a position not between the first focusing lens group (13) and the second focusing lens group (14) by a six-degree-of-freedom translation stage (16); the mechanical switch of the ultrafast laser (1) is turned on, and the laser passes through the first beam splitter (2) and is semi-transmitted and semi-reflected to be divided into transmitted light and reflected light with the same energy, the reflected light is shielded, and the angles of the first beam splitter (1) and the first dichroic mirror (3) are adjusted so that the transmitted light passes through the first aperture (4) and the second aperture (12) to achieve beam calibration; the transmitted light is shielded, and the angles of the reflector (8) and the second dichroic mirror (9) are adjusted so that the reflected light passes through the reflector (8) and the second dichroic mirror (9) in sequence and then passes through the first aperture (4) and the second aperture (12) at the same time to achieve calibration; after calibration, the first focusing lens group (13) and the second focusing lens group (14) are installed after calibration, the transmitted light finally passes through the first focusing lens group (13) to form a first processing light path, and the reflected light finally passes through the second focusing lens group (14) to form a second processing light path.

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