Laser curved edge cutting method for transparent material

Abstract

The invention provides a laser curved edge cutting method for a transparent material, belongs to the technical field of laser cutting, and aims to solve the technical problem that a curved surface structure is difficult to cut. The cutting method comprises the following steps that (1) ultrafast laser output by an ultrafast laser is a linear polarization Gaussian beam, and the linear polarization Gaussian beam is converted into a left-hand circular polarization Gaussian beam or a right-hand circular polarization Gaussian beam; (2) converting the left-handed circular polarization or right-handed circular polarization Gaussian beam into an Airy beam, processing and positioning through a coaxial imaging system, and setting laser processing parameters; (3) carrying out laser scanning on the transparent material by using Airy light beams according to a preset speed and track, and forming a modified layer in the transparent material; and (4) splitting the transparent material. The curved cutting section is obtained by utilizing the characteristic of bending propagation of the Airy beam, the problem that the section is a plane after the transparent material is cut by laser in the past is solved, and meanwhile, the tedious process of grinding and polishing the section is omitted.

Description

Technical Field

[0001] The invention belongs to the technical field of laser cutting, and in particular relates to laser curved edge cutting. Background Art

[0002] Laser processing has been widely used in the cutting and processing of transparent materials (such as quartz glass, silicon carbide wafers, sapphire wafers, etc.) due to its significant advantages of high precision, high quality and high efficiency. In recent years, laser invisible cutting technology has emerged as one of the mainstream means of cutting transparent materials. This technology uses a shaped and focused laser to focus on a specific position inside the material to be processed, thereby forming a modified layer, and then achieves the cutting purpose through mechanical splitting or film expansion processes.

[0003] However, the existing cutting methods, including traditional mechanical cutting, laser direct cutting and laser invisible cutting, usually produce cutting sections in the form of vertical or inclined planes. When faced with the processing needs of curved sections, this traditional cutting method exposes many disadvantages. Since it cannot directly form a curved section, it is often necessary to perform additional grinding and polishing on the cut plane section to obtain the desired curved section shape. In addition, after completing the grinding and polishing, additional steps such as cleaning or chemical treatment are required to remove the residues or impurities generated during the processing. The whole process is extremely time-consuming and labor-intensive. In addition, for thinner materials, there is also the risk of cracking during the mechanical polishing process. This is because the structural strength of the thin material itself is relatively low, and it is easy to crack under the external force it is subjected to during mechanical polishing, which leads to the scrapping of the material and the increase of processing costs.

[0004] To sum up, the existing transparent material cutting technology has many shortcomings when facing the demand for curved cross-sections. There is an urgent need for a new laser processing technology that can directly cut curved cross-sections and is suitable for thin material processing to overcome the limitations of current technology, improve the efficiency and quality of transparent material processing, and reduce processing costs and material loss.

[0005] Patent publication number TW201728542A discloses a system and method for processing a non-circular edge of a glass substrate or cutting a glass substrate using two Airy beams. The method includes generating a first and a second Airy beam and intersecting them at an intersection to define a curved intensity distribution near the intersection, wherein the first and second Airy beams have respective local curvature radii Ra and Rb. The method also includes scanning the curved intensity distribution along the non-circular outer edge or along a scanning path through the glass to form a circular outer edge on the glass substrate having a curvature radius Re that is less than the first and second local curvature radii Ra and Rb. The curvature radius Re can be adjusted by changing the beam angle between the first and second Airy beams. Although this patent can process a curved surface with a certain curvature, its structure is complex and requires two sets of laser devices. Moreover, when processing thin materials, the curved surface structure is not easy to control. Summary of the invention

[0006] In response to the above technical problems, the present invention proposes a laser curved edge cutting method for transparent materials, which utilizes the characteristics of the curved propagation of the Airy beam to obtain the curved cutting section, solving the problem that the cross-sections of transparent materials after laser cutting are all flat, while eliminating the tedious process of grinding and polishing the cross-sections.

[0007] In order to achieve the above object, the technical solution of the present invention is achieved as follows:

[0008] A method for laser curved edge cutting of a transparent material, comprising the following steps:

[0009] (1) The linearly polarized Gaussian beam output by the ultrafast laser is converted into a left-handed circularly polarized or right-handed circularly polarized Gaussian beam;

[0010] (2) converting the left-handed circularly polarized or right-handed circularly polarized Gaussian beam into an Airy beam, performing processing positioning through a coaxial imaging system, and setting laser processing parameters;

[0011] (3) moving the Airy beam toward the transparent material at a predetermined speed and trajectory to form a modified layer inside the transparent material;

[0012] (4) Splitting of transparent materials.

[0013] In the step (1), the linearly polarized Gaussian light beam is firstly passed through a 1 / 2 wave plate to adjust the polarization direction.

[0014] The linearly polarized Gaussian beam is converted into a left-handed circularly polarized or right-handed circularly polarized Gaussian beam through a 1 / 4 wave plate.

[0015] The wavelength of the linearly polarized Gaussian light beam is 400nm-1200nm, the pulse width range is 50fs-20ps, and the repetition frequency is 10kHz-1000kHz.

[0016] In the step (2), a holographic phase spectrum is loaded into a spatial light modulator to convert the left-handed circularly polarized or right-handed circularly polarized Gaussian beam into an Airy beam.

[0017] In the step (2), the Airy beam is focused by a focusing objective lens, and the focal length is 0.3 mm to 15 mm.

[0018] The predetermined speed in step (3) is 10 mm / s to 1000 mm / s.

[0019] The transparent material is any one of glass, sapphire, diamond, silicon carbide, lithium niobate, zinc oxide or aluminum nitride; the thickness of the transparent material to be cut is 200um to 5mm.

[0020] In the step (4), the fragmentation is performed by heating the modified area using a long pulse laser.

[0021] The long pulse laser is output from a CO2 laser, has a wavelength of 9um-11um, and a pulse width of 50ns-500ns; the long pulse laser is focused by a focusing mirror with a focal length of 100mm-200mm.

[0022] Beneficial effects of the present invention: The present invention uses a spatial light modulator to spatially shape an ultrafast laser beam into an Airy beam, and utilizes the non-diffraction propagation characteristics of the Airy beam along a curved trajectory in free space to form an arc-shaped modified layer in the transparent material, and then uses a long pulse laser to heat the modified area to achieve splitting. This cutting method can achieve arc-shaped cross-section cutting of transparent materials without obvious edge collapse and residue. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0024] Figure 1 Flow chart for laser curved edge cutting of transparent materials. DETAILED DESCRIPTION

[0025] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0026] A method for laser curved edge cutting of a transparent material, comprising the following steps:

[0027] (1) The ultrafast laser output by the ultrafast laser is a linearly polarized Gaussian beam, and the linearly polarized Gaussian beam is converted into a left-handed circularly polarized or right-handed circularly polarized Gaussian beam;

[0028] (2) converting the left-handed circularly polarized or right-handed circularly polarized Gaussian beam into an Airy beam, performing processing positioning through a coaxial imaging system, and setting laser processing parameters;

[0029] (3) The Airy beam is moved toward the transparent material at a predetermined speed and trajectory to form a modified layer inside the transparent material.

[0030] (4) Splitting of transparent materials.

[0031] The ultrafast laser is a special type of laser that can output laser pulses with extremely short pulse widths. The output laser pulse width is usually in picoseconds (10 -12 seconds) or even shorter femtoseconds (10 -15 Seconds) level.

[0032] Preferably, the wavelength of the ultrafast laser is 400 nm to 1200 nm, the pulse width ranges from 50 fs to 20 ps, ​​and the repetition frequency is 10 kHz to 1000 kHz.

[0033] The linearly polarized Gaussian beam is adjusted in polarization direction through a 1 / 2 wave plate.

[0034] The linearly polarized Gaussian beam is converted into a left-handed circularly polarized or right-handed circularly polarized Gaussian beam through a quarter wave plate. When the polarization direction of the linearly polarized light is incident at an angle of 45° to the optical axis of the quarter wave plate, after passing through the quarter wave plate, the o-light and the e-light produce a phase difference of π / 2. According to the principle of polarization synthesis of light, the electric field vector endpoint of the outgoing light will make a circular motion in a plane perpendicular to the propagation direction, thereby forming circularly polarized light.

[0035] If the polarization direction of the linearly polarized light is incident at an angle of 45° clockwise relative to the optical axis of the 1 / 4 wave plate, the outgoing light will form a right-handed circularly polarized Gaussian beam, that is, the endpoint of the electric field vector moves in a circular motion in the clockwise direction; conversely, if it is incident at an angle of 45° counterclockwise, a left-handed circularly polarized Gaussian beam will be obtained, and its electric field vector endpoint moves in a circular motion in the counterclockwise direction.

[0036] The conversion of Gaussian beams into Airy beams is mainly based on the principles of diffraction and phase modulation of light. Airy beams have unique phase distribution and intensity distribution characteristics. Their light intensity in the lateral direction presents a form similar to the Airy function. There are a series of side lobes on one side and the light intensity gradually decreases. The main lobe will "bend" along a specific trajectory during propagation, and at the same time, it will exhibit self-acceleration and non-diffraction characteristics in the propagation direction. To achieve the conversion, it is necessary to change the wavefront phase and intensity distribution of the Gaussian beam to make it conform to the corresponding characteristics of the Airy beam. This is usually achieved with the help of some specific optical elements or technical means. Common conversion methods are modulation using optical elements, based on spatial light modulators, and using holographic optical elements.

[0037] Preferably, in step (2), a holographic phase spectrum is loaded into a spatial light modulator to convert the left-handed circularly polarized or right-handed circularly polarized Gaussian beam into an Airy beam. A spatial light modulator (SLM) is an optical device that can dynamically control the wavefront phase, amplitude and other characteristics of light. It is usually implemented based on technologies such as liquid crystal and micro-electromechanical systems, and contains a large number of independently controllable pixel units. The optical modulation amount corresponding to each pixel is changed through electrical signals or computer control, thereby flexibly modulating the incident light beam.

[0038] The polarization direction of the linear polarized light is adjusted by the 1 / 2 wave plate, thereby changing the rotation direction of the circularly polarized light vector, and finally achieving the adjustment of the bending direction of the Airy beam.

[0039] In the step (2), the Airy beam is focused by a focusing objective lens, and the focal length is 0.3 mm to 15 mm.

[0040] The predetermined speed in step (3) is 10 mm / s to 1000 mm / s. Preferably, the transparent material to be cut is supported by a high-speed translation stage and moves at a predetermined speed and trajectory.

[0041] The transparent material is any one of glass, sapphire, diamond, silicon carbide, lithium niobate, zinc oxide or aluminum nitride; the thickness of the transparent material to be cut is 200um to 5mm.

[0042] In the step (4), the fragmentation is performed by heating the modified area using a long pulse laser.

[0043] The long pulse laser is output from a CO2 laser, has a wavelength of 9um-11um, and a pulse width of 50ns-500ns; the long pulse laser is focused by a focusing mirror with a focal length of 100mm-200mm.

[0044] Example 1

[0045] A method for cutting a transparent material by laser curved edges, wherein the cutting process is as follows: Figure 1 As shown, the following steps are included:

[0046] (1) A sapphire sheet sample with a length and width of 10 mm × 10 mm and a thickness of 500 μm was selected, and its surface was ultrasonically cleaned with acetone, anhydrous ethanol and deionized water respectively, and then dried to obtain a clean sapphire sheet sample, which was then fixed on the stage of a high-speed translation stage;

[0047] (2) Build the laser processing optical path and set the picosecond laser parameters: laser wavelength is 1064 nm, pulse width is 10 ps, ​​repetition frequency is 50 kHz, and power is 5 W;

[0048] (3) adjusting the half wave plate and the quarter wave plate to adjust the light beam to a left-handed circularly polarized Gaussian beam, and loading the calculated holographic phase spectrum into the spatial light modulator to generate an Airy beam through the spatial light modulator;

[0049] (4) Use an objective lens (10x, Na 0.25) to focus the Airy beam, combine with the coaxial imaging system, adjust the focus position of the Airy beam inside the sapphire sample through the z-axis of the high-speed translation stage, set the laser scanning point spacing to 15 μm, and start laser scanning to form a modified area inside the sapphire sample;

[0050] (5) Set the CO2 laser parameters: laser wavelength is 10.6 μm, pulse width is 200 ns, and power is 80 W;

[0051] (6) The CO2 laser is focused and scanned using a flat-field scanning lens with a focal length of 200 mm to heat the modified area to cause crack growth, thereby achieving the sapphire sample splitting.

[0052] Example 2

[0053] A method for cutting a transparent material by laser curved edges, wherein the cutting process is as follows: Figure 1 As shown, the following steps are included:

[0054] (1) A sapphire sheet sample with a length and width of 10 mm × 10 mm and a thickness of 400 μm was selected, and its surface was ultrasonically cleaned with acetone, anhydrous ethanol and deionized water respectively, and then dried to obtain a clean sapphire sheet sample, which was then fixed on the stage of a high-speed translation stage;

[0055] (2) Build the laser processing optical path and set the picosecond laser parameters: laser wavelength is 1064 nm, pulse width is 10 ps, ​​repetition frequency is 50 kHz, and power is 5 W;

[0056] (3) adjusting the half wave plate and the quarter wave plate to adjust the light beam to a right-handed circularly polarized Gaussian beam, and loading the calculated holographic phase spectrum into the spatial light modulator to generate an Airy beam through the spatial light modulator;

[0057] (4) Use an objective lens (10x, Na 0.25) to focus the Airy beam, combine with the coaxial imaging system, adjust the focus position of the Airy beam inside the sapphire sample through the z-axis of the high-speed translation stage, set the laser scanning point spacing to 15 μm, and start laser scanning to form a modified area inside the sapphire sample;

[0058] (5) Set the CO2 laser parameters: laser wavelength is 10.6 μm, pulse width is 200 ns, and power is 80 W;

[0059] (6) The CO2 laser is focused and scanned using a flat-field scanning lens with a focal length of 200 mm to heat the modified area to cause crack growth, thereby achieving the sapphire sample splitting.

[0060] Example 3

[0061] A method for laser curved edge cutting of a transparent material, comprising the following steps:

[0062] (1) A sapphire sheet sample with a length and width of 10 mm × 10 mm and a thickness of 300 μm was selected, and its surface was ultrasonically cleaned with acetone, anhydrous ethanol and deionized water respectively, and then dried to obtain a clean sapphire sheet sample, which was then fixed on the stage of a high-speed translation stage;

[0063] (2) Build the laser processing optical path and set the picosecond laser parameters: laser wavelength is 532 nm, pulse width is 5 ps, repetition frequency is 100 kHz, and power is 10 W;

[0064] (3) adjusting the half wave plate and the quarter wave plate to adjust the light beam to a left-handed circularly polarized Gaussian beam, and loading the calculated holographic phase spectrum into the spatial light modulator to generate an Airy beam through the spatial light modulator;

[0065] (4) Use an objective lens (10x, Na 0.25) to focus the Airy beam, combine with the coaxial imaging system, adjust the focus position of the Airy beam inside the sapphire sample through the z-axis of the high-speed translation stage, set the laser scanning point spacing to 15 μm, and start laser scanning to form a modified area inside the sapphire sample;

[0066] (5) Set the CO2 laser parameters: laser wavelength is 10.6 μm, pulse width is 200 ns, and power is 70 W;

[0067] (6) The CO2 laser is focused and scanned using a flat-field scanning lens with a focal length of 100 mm to heat the modified area to cause crack growth, thereby achieving the sapphire sample splitting.

[0068] Example 4

[0069] A method for cutting a transparent material by laser curved edges, wherein the cutting process is as follows: Figure 1 As shown, the following steps are included:

[0070] (1) A sapphire sheet sample with a length and width of 10 mm × 10 mm and a thickness of 500 μm was selected, and its surface was ultrasonically cleaned with acetone, anhydrous ethanol and deionized water respectively, and then dried to obtain a clean sapphire sheet sample, which was then fixed on the stage of a high-speed translation stage;

[0071] (2) Build the laser processing optical path and set the picosecond laser parameters: laser wavelength is 532 nm, pulse width is 10 ps, ​​repetition frequency is 50 kHz, and power is 5 W;

[0072] (3) adjusting the half wave plate and the quarter wave plate to adjust the light beam to a left-handed circularly polarized Gaussian beam, and loading the calculated holographic phase spectrum into the spatial light modulator to generate an Airy beam through the spatial light modulator;

[0073] (4) Use an objective lens (10x, Na 0.25) to focus the Airy beam, combine with the coaxial imaging system, adjust the focus position of the Airy beam inside the sapphire sample through the z-axis of the high-speed translation stage, set the laser scanning point spacing to 15 μm, and start laser scanning to form a modified area inside the sapphire sample;

[0074] (5) Set the CO2 laser parameters: laser wavelength is 10.6 μm, pulse width is 200 ns, and power is 80 W;

[0075] (6) The CO2 laser is focused and scanned using a flat-field scanning lens with a focal length of 200 mm to heat the modified area to cause crack growth, thereby achieving the sapphire sample splitting.

[0076] Example 5

[0077] A method for cutting a transparent material by laser curved edges, wherein the cutting process is as follows: Figure 1 As shown, the following steps are included:

[0078] (1) A sapphire sheet sample with a length and width of 10 mm × 10 mm and a thickness of 500 μm was selected, and its surface was ultrasonically cleaned with acetone, anhydrous ethanol and deionized water respectively, and then dried to obtain a clean sapphire sheet sample, which was then fixed on the stage of a high-speed translation stage;

[0079] (2) Build the laser processing optical path and set the picosecond laser parameters: laser wavelength is 1064 nm, pulse width is 50 fs, repetition frequency is 10 kHz, and power is 5 W;

[0080] (3) adjusting the half wave plate and the quarter wave plate to adjust the light beam to a left-handed circularly polarized Gaussian beam, and loading the calculated holographic phase spectrum into the spatial light modulator to generate an Airy beam through the spatial light modulator;

[0081] (4) Use an objective lens (10x, Na 0.25) to focus the Airy beam, combine with the coaxial imaging system, adjust the focus position of the Airy beam inside the sapphire sample through the z-axis of the high-speed translation stage, set the laser scanning point spacing to 15 μm, and start laser scanning to form a modified area inside the sapphire sample;

[0082] (5) Set the CO2 laser parameters: laser wavelength is 10.6 μm, pulse width is 50 ns, and power is 60 W;

[0083] (6) The CO2 laser is focused and scanned using a flat-field scanning lens with a focal length of 150 mm to heat the modified area to cause crack growth, thereby achieving the sapphire sample splitting.

[0084] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for laser curved edge cutting of transparent materials, characterized in that: The following steps are involved: (1) The linearly polarized Gaussian beam output by the ultrafast laser is converted into a left-handed circularly polarized or right-handed circularly polarized Gaussian beam; (2) converting the left-handed circularly polarized or right-handed circularly polarized Gaussian beam into an Airy beam, performing processing positioning through a coaxial imaging system, and setting laser processing parameters; (3) moving the Airy beam toward the transparent material at a predetermined speed and trajectory to form a modified layer inside the transparent material; (4) Splitting of transparent materials.

2. The method for laser curved edge cutting of transparent materials according to claim 1, characterized in that: In the step (1), the linearly polarized Gaussian light beam is firstly passed through a 1 / 2 wave plate to adjust the polarization direction.

3. The laser curved edge cutting method of transparent material according to claim 2, characterized in that: The linearly polarized Gaussian beam is converted into a left-handed circularly polarized or right-handed circularly polarized Gaussian beam through a quarter wave plate.

4. The laser curved edge cutting method of transparent material according to claim 1, characterized in that: The wavelength of the linearly polarized Gaussian light beam is 400nm-1200nm, the pulse width range is 50fs-20ps, and the repetition frequency is 10kHz-1000kHz.

5. The method for laser curved edge cutting of transparent materials according to any one of claims 1 to 4, characterized in that: In the step (2), a holographic phase spectrum is loaded into a spatial light modulator to convert the left-handed circularly polarized or right-handed circularly polarized Gaussian beam into an Airy beam.

6. The method for laser curved edge cutting of transparent materials according to claim 5, characterized in that: In the step (2), the Airy beam is focused by a focusing lens, and the focal length is 0.3 mm to 15 mm.

7. The laser curved edge cutting method of transparent material according to claim 1, characterized in that: The predetermined speed in step (3) is 10 mm / s to 1000 mm / s.

8. The method for laser curved edge cutting of transparent materials according to claim 1, characterized in that: The transparent material is any one of glass, sapphire, diamond, silicon carbide, lithium niobate, zinc oxide or aluminum nitride; the thickness of the transparent material to be cut is 200um to 5mm.

9. The laser curved edge cutting method of transparent material according to claim 1, characterized in that: In the step (4), the fragmentation is performed by heating the modified area using a long pulse laser.

10. The laser curved edge cutting method of transparent material according to claim 9, characterized in that: The long pulse laser is output from a CO2 laser, has a wavelength of 9um-11um, and a pulse width of 50ns-500ns; the long pulse laser is focused by a focusing mirror with a focal length of 100mm-200mm.

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