CN111618453A

CN111618453A - Ultrafast laser cutting method and device for transparent material

Info

Publication number: CN111618453A
Application number: CN202010593316.1A
Authority: CN
Inventors: 蒋仕彬
Original assignee: SUZHOU TUSEN LASER CO Ltd
Current assignee: SUZHOU TUSEN LASER CO Ltd
Priority date: 2020-06-26
Filing date: 2020-06-26
Publication date: 2020-09-04

Abstract

The invention discloses an ultrafast laser cutting method and a device for transparent materials, wherein a semiconductor laser is modulated to provide pulse train seed laser, the pulse train seed laser is amplified by an optical fiber amplifier and then is converted into green light by a frequency doubling crystal, the laser pulse train is focused to a position to be processed of the transparent material by a Bessel cutting head, more than three focusing points are formed in the processed material, and the transparent material is cut by moving the focusing position; each laser pulse train comprises at least four laser pulses, the pulse width is 50-60 ps, the peak power is more than 1MW, and the time between adjacent laser pulses is 10-20 ns; the interval time between adjacent pulse trains is greater than 100 ns; the laser pulse width broadening quantity and the compression quantity do not exceed 20% of the seed laser pulse width. The invention ensures the reliability of the cutting light beam, effectively utilizes the waste heat of the previous pulse, ensures the cutting processing quality and realizes the cutting of straight lines and various special-shaped shapes of materials.

Description

Ultrafast laser cutting method and device for transparent material

Technical Field

The invention relates to a laser processing method, in particular to an ultrafast laser cutting method and device for cutting and processing a transparent material.

Background

Glass and sapphire transparent materials have become an indispensable part of people's daily life, and with the development of economy, the demand for glass products is increasing day by day. In the glass and sapphire production industry, glass and sapphire processing is a very important link.

Generally, glass and sapphire processing (cold working) mainly includes polishing, cutting, drilling, engraving, edging, and the like. For the purpose of industrially realizing the above-mentioned glass and sapphire processing, the processing methods adopted in the prior art mainly include a mechanical processing method, a chemical processing method (mainly used for polishing and etching), a high-pressure water jet processing method (mainly used for cutting and drilling), and a laser processing method. Among them, the laser processing method is far superior to other methods in terms of processing speed and degree of automation.

In general, glass and sapphire are laser processed with CO having a wavelength of about 10.6 μm₂The output power of the laser is generally required to be over 100W. CO 2₂Laser processing of glass and sapphire is achieved by laser incidence which causes glass to break when heated. Taking the cutting of sheet glass as an example, CO is added₂Laser beams emitted by the laser are focused on the flat glass, the high-power laser enables the glass to be heated and broken at the focal position of the laser, and the cracks extend to the upper surface and the lower surface of the glass so as to finish cutting. During the thermal cutting process, it is usually necessary to use a quenching nozzle to spray cold water or gas onto the cutting path to break the glass apart. The method has low cutting precision and is difficult to process complex patterns.

The nanosecond pulse laser can be used for laser processing of glass and sapphire to reach the specific CO₂Better processing effect of the laser. With conventional CO₂Different from lasers, the nanosecond laser realizes glass processing by means of micro blasting. Also taking the cutting of the flat glass as an example, the focus of the laser can move in the vertical direction through the 3D scanning galvanometer, and the glass can explode in the micron order at the position where the focus of the laser passes through, and the tiny damages are overlapped in the vertical direction, so that the cutting with higher precision is realized. Such nanosecond lasers also have some drawbacks in glass and sapphire processing. The edge break after nanosecond laser processing is generally greater than 50 microns, however in many applications, edge break less than 20 microns is required.

To achieve laser processing levels of less than 20 microns, ultrafast laser processing may be employed. Picosecond laser pulses are focused on the position to be processed of the transparent material, and the transparent material is processed by moving the focusing position. During processing, the laser beam is focused on the lower surface of the transparent material to be processed, processing is carried out according to a set track, the focus point is gradually raised, and the transparent material is processed from bottom to top. The moving focusing position can be realized by a scanning galvanometer, the output laser passes through the scanning galvanometer and then is focused to the position to be processed of the transparent material by a focusing lens, so that the transparent material is removed in a micron order, and the position of the moving focus of the scanning galvanometer is used for overlapping the removal point in the area to be processed so as to realize processing. During specific processing, a laser beam is focused on the lower surface of the transparent material to be processed, processing is carried out according to a set track, a focus point is gradually raised, and the transparent material is processed from bottom to top. Such ultrafast laser processing has no bevel angle. However, this method is relatively slow.

The processing speed is faster by adopting an ultra-fast laser Bessel cutting method, however, a picosecond free space solid laser is generally adopted in the Bessel cutting. The picosecond free space solid laser is inconvenient to manufacture, poor in reliability, poor in light beam quality and high in price.

Therefore, it would be of great interest to find a new ultrafast picosecond laser for fast, low-cost processing of transparent materials.

Disclosure of Invention

The invention aims to provide an ultrafast laser cutting method for a transparent material, which aims to overcome the problem of limited processing in the prior art and improve the processing precision and speed of the laser transparent material.

Another object of the present invention is to provide a cutting apparatus for a transparent material which implements the processing method.

In order to achieve the purpose of the invention, the technical scheme adopted by the invention is as follows: a ultrafast laser cutting method of a transparent material, modulate and provide a pulse train seed laser with wavelength between 1020 nanometers and 1090 nanometers by the semiconductor laser, use the optical fiber amplifier to carry on the energy amplification with the laser that the seed laser outputs, the laser is changed into the green glow with wavelength between 510 nanometers and 545 nanometers with the frequency doubling crystal after outputting from the optic fibre, focus the above-mentioned green glow laser pulse train to the position to be processed of the transparent material through Bessel cutting head, form the focus point more than three in the processed material, through moving the focus position, realize the cutting to the transparent material;

each laser pulse train comprises at least four laser pulses, the pulse width of each laser pulse is 50-60 ps, the peak power of the pulse is more than 1MW, and the time between adjacent laser pulses in the pulse train is 10-20 ns; the interval time between adjacent pulse trains is greater than 100 ns;

the ultrafast laser beam output by the laser only adopts the optical fiber amplifier to amplify energy, and the laser pulse width broadening quantity and the laser pulse width compression quantity do not exceed 20% of the seed laser pulse width from the seed light to the optical fiber output.

In the technical scheme, the pulse output laser is an ultrafast green laser with the wavelength of 510-545 nanometers. Each pulse train comprises at least four laser pulses, the pulse width is 50-60 ps, the peak power of the pulses is larger than 1MW, the time between every two laser pulses in each pulse train is 10-20 ns, and the interval time between every two pulse trains is larger than 100 ns. The first pulse acts on the material to microcrack the material and increase the temperature of the surrounding material. The second pulse reaches and further rapidly increases the temperature of the surrounding material, increasing the length of the microcracks, before the heat of the surrounding material is dissipated. The third pulse can utilize the waste heat of the first two pulses to effectively increase the length of the microcrack, and so on, the pulse train can greatly improve the length of the microcrack. At the same time, the bessel cutting head may produce multiple focal points, e.g., more than three focal points, in the material. When the microcracks of different focus points are connected together, the processed material can generate microcracks from top to bottom, so that the cutting is realized.

During laser machining, thermal diffusion requires microsecond time levels, but subsequent pulses typically arrive at around ten and several nanoseconds. A typical pulse interval for a burst is approximately ten nanoseconds, much less than the microsecond time required for thermal diffusion. The waste heat from the previous pulse can thus be used efficiently.

According to the preferable technical scheme, the number of the laser pulses in each laser pulse train is 4-50.

More preferably, the number of laser pulses in each laser pulse train is 4 to 15.

In the above technical solution, the transparent material is one of glass, crystalline material, semiconductor and plastic.

In the above technical solution, the cutting may be a vertical cutting or an angular cutting.

In order to realize another purpose of the invention, the invention provides an ultrafast laser cutting device of a transparent material, which comprises a laser generating device, a light steering component, an optical head and a working platform, wherein a three-dimensional movement mechanism is arranged between the optical head and the working platform, the laser generating device is an ultrafast pulse train laser, the ultrafast pulse train laser mainly comprises a semiconductor laser, an optical fiber amplifier, a collimator and a frequency doubling crystal, and the semiconductor laser provides pulse train seed laser with the wavelength of 1020-1090 nanometers; the optical head is a Bessel cutting head; the pulse train seed laser emitted by the semiconductor laser enters the collimator after being amplified by the optical fiber amplifier, the ultrafast pulse train laser is output and then converted into green light by the frequency doubling crystal, the green light is guided into the Bessel cutting head by the light steering assembly, and more than three focusing points are formed inside a processed material on the working platform.

In the technical scheme, a rack is fixedly arranged above the working platform, the plane where the working platform is located is an X-Y plane, a Z axis is perpendicular to the X-Y plane, the laser generating device is positioned on the rack, an X axis movement module is arranged on the front side of the rack, a Z axis movement module is arranged on a movement part of the X axis movement module, the Bessel cutting head is fixed on the movement part of the Z axis movement module, and the working platform is provided with a Y axis movement mechanism; the light steering component comprises 4 total reflection lenses, wherein a first lens and a second lens are fixed on the rack and guide laser beams to the upper part of the Bezier cutting head, and a third lens and a fourth lens are arranged on a moving part of the Z-axis movement module, so that the laser beams are turned to be in a vertical downward direction and enter the Bezier cutting head. Thereby, the third lens, the fourth lens, the Bessel cutting head,

In the technical scheme, each laser pulse train comprises at least four laser pulses, the pulse width of each laser pulse is 50-60 ps, the peak power of the pulse is more than 1MW, and the time between adjacent laser pulses in the pulse train is 10-20 ns; the separation time between adjacent bursts is greater than 100 ns.

Due to the application of the technical scheme, compared with the prior art, the invention has the following advantages:

1. the invention utilizes the optical fiber amplifier to be matched with the Bessel cutting head, thereby ensuring the reliability of the cutting beam, and simultaneously, effectively utilizing the waste heat of the previous pulse by limiting the time between the adjacent laser pulses in the pulse train, thereby ensuring the quality of cutting processing;

2. the laser output wavelength of the invention is 510 nm-545 nm, so the focused light spot has small diameter and can reach more precise laser processing;

3. according to the invention, through reasonable matching of the light steering assembly and the movement mechanism, a three-dimensional processing space is formed, and linear and various special-shaped shapes of materials are cut through combined movement of three shafts.

Drawings

FIG. 1 is a schematic block diagram of an ultrafast burst laser according to an embodiment of the present invention;

fig. 2 is a schematic structural diagram of an embodiment of the present invention.

Detailed Description

The invention is further described with reference to the following figures and examples:

the first embodiment is as follows: referring to fig. 2, the ultrafast laser cutting device for the transparent material comprises an ultrafast pulse train laser, a light steering assembly, a bessel cutting head and a working platform, wherein the transparent material to be processed is placed on the working platform.

As shown in fig. 1, in the ultrafast burst laser, a semiconductor laser forms an ultrafast burst seed laser, a multi-stage or single-stage fiber amplifier, a collimator, and a frequency doubling crystal are provided, the semiconductor laser provides a burst seed laser with a wavelength of 1020 nm to 1090 nm, the burst seed laser is amplified by the fiber amplifier, enters the collimator, and is converted into a green light with a wavelength of 510nm to 545nm by the frequency doubling crystal, and the ultrafast burst laser is output. The laser pulse train comprises at least four laser pulses, the pulse width of each laser pulse is 50-60 ps, the peak power of the pulse is larger than 1MW, the time between every two laser pulses in each laser pulse train is 10-20 ns, the interval time between every two laser pulse trains is larger than 100ns, and the number of the laser pulses in each laser pulse train is 4-50. The ultrafast laser beam output by the laser only adopts the optical fiber amplifier to amplify energy, and the laser pulse width broadening quantity and the laser pulse width compression quantity do not exceed 20% of the seed laser pulse width from the seed light to the optical fiber output.

In this embodiment, a three-dimensional motion mechanism is provided, which is configured to: a rack is fixedly arranged above the working platform, the plane where the working platform is located is an X-Y plane, a Z axis is perpendicular to the X-Y plane, the ultrafast pulse train laser is located on the rack, and the light emitting direction of the laser is the side of the rack.

An X-axis movement module is arranged on the front side of the rack, a Z-axis movement module is arranged on a movement part of the X-axis movement module, the Bessel cutting head is fixed on the movement part of the Z-axis movement module, and the working platform is provided with a Y-axis movement mechanism.

The light steering component comprises 4 total reflection lenses of 45 degrees, wherein a first lens 1 and a second lens 2 are fixed on the frame, laser beams emitted to the side are guided to the horizontal front of the laser, a third lens 3 and a fourth lens 4 are arranged on a moving piece of the Z-axis movement module, wherein the third lens 3 converts the horizontal laser beams to the left into forward beams, and the fourth lens 4 is positioned right above the Bessel cutting head, so that the laser beams are converted into the vertical downward direction and enter the Bessel cutting head.

The pulse series laser beam passes through the Bessel cutting head, more than three focusing points are formed inside a processed material on the working platform, and the linear and various special-shaped shapes of the material are cut through the combined motion of three shafts.

Claims

1. An ultrafast laser cutting method for transparent material, which provides a pulse train seed laser with a wavelength between 1020 nm and 1090 nm by modulation of a semiconductor laser, and amplifies the energy of the laser output by the seed laser by an optical fiber amplifier, characterized in that: the method comprises the steps that laser is output from an optical fiber and then is converted into green light with the wavelength of 510-545 nanometers through a frequency doubling crystal, the green light laser pulse train is focused to a position to be processed of a transparent material through a Bessel cutting head, more than three focusing points are formed inside the processed material, and the transparent material is cut by moving the focusing position;

2. The ultrafast laser cutting method for transparent material according to claim 1, wherein: the number of laser pulses in each laser pulse train is 4-50.

3. The ultrafast laser cutting method for transparent material according to claim 2, wherein: the number of laser pulses in each laser pulse train is 4-15.

4. The ultrafast laser cutting method for transparent material according to claim 1, wherein: the transparent material is one of glass, crystalline material, semiconductor, and plastic.

5. The utility model provides an ultrafast laser cutting device for transparent material, turns to subassembly, optical head, work platform including laser generating device, light, is equipped with three-dimensional motion mechanism, its characterized in that between optical head and work platform: the laser generating device is an ultrafast pulse train laser, the ultrafast pulse train laser mainly comprises a semiconductor laser, an optical fiber amplifier, a collimator and a frequency doubling crystal, and the semiconductor laser provides pulse train seed laser with the wavelength of 1020-1090 nanometers; the optical head is a Bessel cutting head; the pulse train seed laser emitted by the semiconductor laser enters the collimator after being amplified by the optical fiber amplifier, the ultrafast pulse train laser is output and then converted into green light by the frequency doubling crystal, the green light is guided into the Bessel cutting head by the light steering assembly, and more than three focusing points are formed inside a processed material on the working platform.

6. The ultrafast laser cutting apparatus for transparent materials of claim 5, wherein: a rack is fixedly arranged above the working platform, the plane where the working platform is located is an X-Y plane, a Z axis is perpendicular to the X-Y plane, the laser generating device is positioned on the rack, an X axis movement module is arranged on the front side of the rack, a Z axis movement module is arranged on a movement part of the X axis movement module, the Bessel cutting head is fixed on the movement part of the Z axis movement module, and the working platform is provided with a Y axis movement mechanism; the light steering component comprises 4 total reflection lenses, wherein a first lens and a second lens are fixed on the rack and guide laser beams to the upper part of the Bezier cutting head, and a third lens and a fourth lens are arranged on a moving part of the Z-axis movement module, so that the laser beams are turned to be in a vertical downward direction and enter the Bezier cutting head.

7. The ultrafast laser cutting apparatus for transparent materials of claim 5, wherein: each laser pulse train comprises at least four laser pulses, the pulse width of each laser pulse is 50-60 ps, the peak power of the pulse is more than 1MW, and the time between adjacent laser pulses in the pulse train is 10-20 ns; the separation time between adjacent bursts is greater than 100 ns.

8. The ultrafast laser cutting apparatus for transparent materials of claim 5, wherein: the number of laser pulses in each laser pulse train is 4-50.