CN114571086A

CN114571086A - Nanosecond laser-induced plasma composite femtosecond laser processing device and processing method

Info

Publication number: CN114571086A
Application number: CN202111678468.2A
Authority: CN
Inventors: 卢希钊; 陈嘉林; 姜峰; 江安娜
Original assignee: Huaqiao University
Current assignee: Huaqiao University
Priority date: 2021-12-31
Filing date: 2021-12-31
Publication date: 2022-06-03
Anticipated expiration: 2041-12-31
Also published as: CN114571086B

Abstract

The invention discloses a nanosecond laser-induced plasma composite femtosecond laser processing device and a processing method, wherein the processing device comprises a femtosecond laser, a nanosecond laser, a focusing lens, a transparent workpiece, a polishing target material, a workbench and a clamp; the polishing target material is arranged on a workbench, the transparent workpiece is arranged on a clamp, and the transparent workpiece and the polishing target material are arranged up and down; the nanosecond laser emits nanosecond laser, the nanosecond laser bombards a polishing target material through the focusing of a focusing lens and a transparent workpiece to generate a metal plasma group, and the metal plasma group is transferred to the back of the transparent workpiece and reflects and etches the front of the transparent workpiece to generate graphitization etching; the femtosecond laser emits femtosecond laser, and the femtosecond laser is focused on the transparent workpiece through the focusing lens and removes the generated graphitized etching. It has the following advantages: the method has huge application prospect in the field of micro-nano manufacturing, realizes the requirement of high-precision machining quality in industry, and solves the machining problem of the transparent hard and brittle material workpiece.

Description

Nanosecond laser-induced plasma composite femtosecond laser processing device and processing method

Technical Field

The invention relates to the technical field of efficient precision machining methods, in particular to a device and a method for machining a transparent hard and brittle material by coupling nanosecond laser-induced plasma with femtosecond laser.

Background

Due to the special requirements of the industrial field on some high-precision parts, some parts often have precise shapes and various sizes, the femtosecond processing quality is high, but the processing efficiency is low, and the traditional cutter cutting method needs a plurality of working procedures, so that the processing efficiency is low due to excessive processing working procedures. Therefore, machining these precise high quality features becomes a difficult process.

The transparent hard and brittle material has the characteristics of high hardness, high brittleness, low fracture toughness and the like, the elastic limit and the strength of the material are very close, the material belongs to a difficult-to-machine material, the machined surface of the material is easy to generate micro cracks, a subsurface damage layer and other defects, the heat conductivity of the transparent hard and brittle material is poor, the temperature gradient of a heat affected zone is high, and the heat cracks are easy to generate in the machining process. By adopting the traditional processing method of the transparent hard and brittle material, cracks and pits can be generated on the surface of a workpiece by cutting, grinding and polishing, and the processing precision and efficiency are low, so that the requirement of high-precision processing of the material cannot be met.

With the continuous development of lasers, the ultra-short pulse laser fine processing technology is mature, ultrafine micromachining (submicron to nanometer scale) can be realized, precise three-dimensional processing inside transparent materials can be realized, the thermal influence is small, and the processing material range is wide. Compared with long pulse laser, the microstructure processing quality processed by the ultrashort pulse laser is greatly improved, but the processing cost is high, and the processing speed is not high when the cold processing is completely realized.

Focused ion beam processing technology has been regarded as the most potential micro-nano processing means due to its high resolution processing characteristics. However, the low processing efficiency of the single-point processing mode seriously hinders the development, and the processing process needs a vacuum environment, so that the cost is high, the quality of the processed surface is limited, the process is expensive, and the time consumption is high, so that the method is not widely applied to the industry as a micro-nano processing means at the present stage.

Disclosure of Invention

The invention provides a nanosecond laser-induced plasma composite femtosecond laser processing device and a processing method, which overcome the defects in the background technology.

One of the technical schemes adopted by the invention for solving the technical problems is as follows: the nanosecond laser-induced plasma composite femtosecond laser processing device comprises a femtosecond laser (2), a nanosecond laser (3), a focusing lens (5), a transparent workpiece (6), a polishing target material (8), a workbench (9) and a clamp (10); the polishing target (8) is arranged on a workbench (9), the transparent workpiece (6) is arranged on a clamp (10), and the transparent workpiece (6) and the polishing target (8) are arranged up and down; the nanosecond laser (3) emits nanosecond laser, the nanosecond laser is focused by the focusing lens (5) and the transparent workpiece (6) to bombard the polishing target (8) to generate metal plasma clusters, and the metal plasma clusters are transferred to the back surface of the transparent workpiece (6) and reflect and etch the front surface of the transparent workpiece (6) to generate graphitization etching; the femtosecond laser (2) emits femtosecond laser, and the femtosecond laser is focused on a transparent workpiece (6) through a focusing lens (5) and removes the generated graphitized etching.

In one embodiment: the laser device also comprises a scanning galvanometer (4), and the femtosecond laser and the nanosecond laser are irradiated to the focusing lens (5) through the scanning galvanometer (4).

In one embodiment: the device is characterized by further comprising a computer control system (1) and a pulse signal coordination generator (11), wherein the computer control system (1) is connected with the pulse signal coordination generator (11), and the pulse signal coordination generator (11) is connected with the femtosecond laser (2) and the nanosecond laser (3).

In one embodiment: the workbench (9) is a lifting workbench, the clamp (10) is a lifting clamp (10) and is provided with a linear motor, and the lifting of the clamp (10) is controlled by the linear motor.

In one embodiment: the polishing device is characterized by further comprising a computer control system (1) and a camera (7), wherein the computer control system (1) is connected with the camera (7), the workbench (9) and the clamp (10), at least one position of the workbench (9) and the clamp (10) is adjusted according to the distribution change condition of the gap between the polishing target (8) and the transparent workpiece (6) shot by the camera (7), and the gap between the polishing target (8) and the transparent workpiece (6) is guaranteed to be a fixed value so that a focusing focus is always on the polishing target (8).

In one embodiment: the transparent workpiece (6) and the polishing target (8) are arranged in an up-and-down spaced manner.

In one embodiment: the distance between the transparent workpiece (6) and the polishing target (8) is 0.05-0.5 mm.

In one embodiment: the material of the polishing target (8) is composed of elements with high atomic number.

The second technical scheme adopted by the invention for solving the technical problems is as follows: the nanosecond laser-induced plasma composite femtosecond laser processing method comprises the following steps:

installing a transparent workpiece (6) on a clamp (10), and installing a polishing target (8) on a workbench (9);

the nanosecond laser (3) emits nanosecond laser, the nanosecond laser is focused by the focusing lens (5) and the transparent workpiece (6) to bombard the polishing target (8) so as to generate metal plasma clusters, the metal plasma clusters are transferred to the back of the transparent workpiece (6) and reflect and etch the front of the transparent workpiece (6), and the raised front temperature of the transparent workpiece (6) is graphitized and etched on the front due to accumulation of enough heat;

the femtosecond laser (2) emits femtosecond laser, and the femtosecond laser is focused on the transparent workpiece (6) through the focusing lens (5) and removes the generated graphitized etching.

Compared with the background technology, the technical scheme has the following advantages:

the nanosecond laser-induced plasma and femtosecond laser composite processing technology is a micro-nano processing technology with low damage and low graphitization, has the advantages of high precision, high processing speed, good surface integrity, small dark damage, small surface roughness, small heat affected zone, good surface quality, simple process, flexible use, easy realization and huge application prospect in the field of micro-nano manufacturing, can be used for carrying out micro-groove processing on the diamond parts, realizes the industrial high-precision processing quality requirement and solves the processing problem of the transparent hard and brittle material workpiece.

Drawings

The invention is further described with reference to the following figures and detailed description.

Fig. 1 is a schematic structural view of a processing apparatus according to the present embodiment.

FIG. 2 is a diagram showing the actual processing effect of the micro-grooves processed by the processing apparatus according to the present embodiment.

Detailed Description

Referring to fig. 1, the device for processing a transparent hard brittle material by coupling nanosecond laser with femtosecond laser comprises a computer control system 1, a femtosecond laser 2, a nanosecond laser 3, a scanning galvanometer 4, a focusing lens 5, a transparent workpiece 6, a CDD camera 7, a polishing target material 8, a workbench 9, a liftable clamp 10 and a pulse signal coordination generator 11; the workbench 9 is a lifting workbench, and the lifting fixture 10 comprises a linear motor and is driven to lift by the linear motor; the computer control system 1 is connected with a pulse signal coordination generator 11, and the pulse signal coordination generator 11 is connected with a femtosecond laser 2 and a nanosecond laser 3; the polishing target material 8 is arranged on a working table 9, the transparent workpiece 6 is arranged on a clamp 10, and the transparent workpiece 6 and the polishing target material 8 are arranged in a vertically spaced manner at a spacing of 0.05-0.5 mm; the nanosecond laser 3 emits nanosecond laser, the nanosecond laser is focused by the scanning galvanometer 4, the focusing lens 5 and the transparent workpiece 6 to bombard the polishing target material 8 so as to generate a metal plasma group, and the metal plasma group is transferred to the back surface of the transparent workpiece 6 and reflects and etches the front surface of the transparent workpiece 6 so as to generate graphitization etching; the femtosecond laser 2 emits femtosecond laser, and the femtosecond laser is focused on a transparent workpiece 6 through a scanning galvanometer 4 and a focusing lens 5 and removes the generated graphitized etching. The femtosecond laser beam generated by the femtosecond laser 2 is coupled with the nanosecond laser beam generated by the nanosecond laser 3 to pass through the scanning galvanometer 4 and the focusing lens 5. The computer control system 1 is connected with a camera 7, a workbench 9 and a clamp 10, and at least one position of the workbench 9 and the clamp 10 is adjusted according to the distribution change condition of the gap between the polishing target material 8 and the transparent workpiece 6 shot by the camera 7, so as to ensure that the gap between the polishing target material 8 and the transparent workpiece 6 is a fixed value and a focusing focus is always on the polishing target material 8.

The transparent workpiece 6 is, for example, a diamond having a moderate thickness and a good shape, and has a good laser transmissivity in all bands or in a specific band, such as diamond, sapphire, glass, etc. If the processed transparent material has better laser transmittance in a certain specific wave band, selecting a laser of the laser in the specific wave band range to enable the laser energy to reach the target material without loss, thereby efficiently generating plasma; meanwhile, the size of the laser spot is matched with the characteristic geometric dimension of the processed part, and preferably, when the characteristic geometric dimension of the processed part is 100 micrometers, the size of the laser spot is controlled to be below 10 micrometers.

The nanosecond laser which is irradiated onto the target material 8 through the transparent workpiece 6 may have various forms, preferably, point laser, line laser and surface laser, wherein the point laser may achieve higher processing precision, and the line laser and the surface laser may achieve higher processing efficiency.

The polishing target material 8 is inert or active, inert plasma does not chemically react with the processed material, such as copper, the generated plasma realizes the removal of the processed material by physical processes of impact, thermal ablation and the like, active plasma chemically reacts with the processed material, and the generated plasma is added with chemical removal while being removed by impact and thermal ablation, so that the removal efficiency is further improved. Preferably, the material of the special-shaped target material is composed of elements with high atomic numbers, so that the formed plasma has larger kinetic energy, and the material removal can be better realized through impact. If the polishing target material 8 is prepared by using an ultra-precision machining technology, preferably, the colored special-shaped target material is machined by using single-point diamond ultra-precision cutting; the black special-shaped target material is processed by single-point ultra-precision grinding, and preferably, a material with good processability is selected as the target material. The roughness of the polishing target material is 10 nanometers, and the surface of the target material has good flatness so as to ensure better plasma emission capability.

The fixture is driven to lift through the linear motor, the transparent workpiece is driven to lift (along the normal direction of the target material), and the linear motor is provided with the high-precision grating ruler to ensure the precision of the normal motion. Preferably, the positioning accuracy of the normal direction movement is better than 0.1 micrometer, and the repeated positioning accuracy is better than 1 micrometer. The gap distribution change condition of the target material and the transparent workpiece is ensured through an online high-resolution CCD camera and an image processing technology, and the linear motor is controlled to move based on the gap change condition, so that the gap between the target material and the processed surface is basically a certain value. And adjusting the gap by utilizing laser energy distribution to obtain better geometric shape precision, and preferably, the gap between the target and the processed surface is 0.05-0.5 mm.

The nanosecond laser-induced plasma composite femtosecond laser processing method comprises the following steps:

installing the transparent workpiece 6 on a clamp 10, and installing the polishing target 8 on a workbench 9;

the nanosecond laser 3 emits nanosecond laser, the nanosecond laser is focused by the focusing lens 5 and the transparent workpiece 6 to bombard the polishing target material 8 to generate metal plasma clusters, the metal plasma clusters are transferred to the back surface of the transparent workpiece 6 and reflect and etch the front surface of the transparent workpiece 6, and the raised front surface temperature of the transparent workpiece 6 is graphitized and etched on the front surface due to accumulation of enough heat; nanosecond laser radiation is focused on the upper surface of the polishing target material 8, the polishing target material 8 absorbs a large amount of laser energy, a thin area surface of the upper surface of the polishing target material 8 is heated and vaporized, vaporized particles continue to absorb the laser energy, when the laser energy is larger than the breakdown threshold of the material of the polishing target material 8, the polishing target material 8 is broken down to generate avalanche ionization so as to form high-temperature and high-pressure plasma, the plasma continues to absorb the laser energy to generate local explosion and carry out etching or deposition on the lower surface of the transparent workpiece 6, and the plasma is composed of non-ionized neutral particles, electrons and ions;

the femtosecond laser 2 emits femtosecond laser, and the femtosecond laser is focused on the transparent workpiece 6 through the focusing lens 5 and removes the generated graphitized etching.

Wherein: nanosecond laser and femtosecond laser synchronously penetrate through a transparent workpiece 6 of a single crystal diamond, the emitted femtosecond laser with low power and far-field divergence angle larger than that of the corresponding nanosecond laser is focused on the inner near surface of the diamond with good transparency, the synchronously emitted nanosecond laser bombards a metal target to generate high-temperature and high-speed deposited metal plasma to be agglomerated on the back surface of the diamond and reflect and etch the diamond with carbonized front surface, the front surface of the diamond with rapidly rising surface temperature generates graphitization etching due to enough heat accumulation, and the good defocusing removing effect of the femtosecond laser on the graphitization is utilized to generate high-efficiency front surface deep etching effect on the diamond in the composite processing method, meanwhile, as the deep groove has graphitization generation, in order to reduce or even inhibit graphitization in the groove, the femtosecond laser of synchronous scanning overcomes the defect of low cold processing efficiency, and removes the diamond inhibiting graphitization.

Application example of the present embodiment: the nanosecond laser is, for example, nanosecond (2 nanosecond < Pulse duration) infrared laser, a diamond microgroove is processed by utilizing a nanosecond laser induced plasma coupled femtosecond laser processing technology, a pure copper metal target material is adopted as the target material, the femtosecond laser is laser with the wavelength of about 1030nm and 200fs, and a 1064nm infrared laser (1-200 nanoseconds) is adopted as a 0.6 nanosecond laser. The laser generates laser beam to focus on the pure iron target material, and generates iron plasma to reversely bombard the back of the diamond, thereby generating ablation and vaporization effects, meanwhile, iron can generate chemical reaction with the diamond to generate iron carbide, and the chemical reaction and mechanical heat removal accelerate the removal of the diamond material. By continuously adjusting the Z-direction position of the lifting fixture, the clearance between the pure iron target and the processed surface of the diamond is basically a certain value (the selected distance is 0.18mm), and better geometric shape precision is obtained. The laser pulse power is 20W, the femtosecond laser is 10W, the laser with the wavelength of 1030nm, the synchronous scanning speed is 0.5mm/s, the laser pulse frequency is 10KHz (synchronous femtosecond laser), and the laser pulse width is 1 ns. The schematic diagram of the processing process is shown in fig. 2.

The above description is only a preferred embodiment of the present invention, and therefore should not be taken as limiting the scope of the invention, which is defined by the appended claims and their equivalents.

Claims

1. Nanosecond laser induction plasma composite femtosecond laser processing device is characterized in that: the device comprises a femtosecond laser (2), a nanosecond laser (3), a focusing lens (5), a transparent workpiece (6), a polishing target material (8), a workbench (9) and a clamp (10); the polishing target (8) is arranged on a workbench (9), the transparent workpiece (6) is arranged on a clamp (10), and the transparent workpiece (6) and the polishing target (8) are arranged up and down; the nanosecond laser (3) emits nanosecond laser, the nanosecond laser is focused by the focusing lens (5) and the transparent workpiece (6) to bombard the polishing target (8) to generate metal plasma clusters, and the metal plasma clusters are transferred to the back surface of the transparent workpiece (6) and reflect and etch the front surface of the transparent workpiece (6) to generate graphitization etching; the femtosecond laser (2) emits femtosecond laser, and the femtosecond laser is focused on a transparent workpiece (6) through a focusing lens (5) and removes the generated graphitized etching.

2. The nanosecond laser-induced plasma composite femtosecond laser processing device according to claim 1, wherein: the laser device also comprises a scanning galvanometer (4), and the femtosecond laser and the nanosecond laser are irradiated to the focusing lens (5) through the scanning galvanometer (4).

3. The nanosecond laser-induced plasma composite femtosecond laser processing device according to claim 1, wherein: the device is characterized by further comprising a computer control system (1) and a pulse signal coordination generator (11), wherein the computer control system (1) is connected with the pulse signal coordination generator (11), and the pulse signal coordination generator (11) is connected with the femtosecond laser (2) and the nanosecond laser (3).

4. The nanosecond laser-induced plasma composite femtosecond laser processing device according to claim 1, wherein: the workbench (9) is a lifting workbench, the clamp (10) is a lifting clamp (10) and is provided with a linear motor, and the lifting of the clamp (10) is controlled by the linear motor.

5. The nanosecond laser-induced plasma composite femtosecond laser processing apparatus according to claim 4, wherein: the polishing device is characterized by further comprising a computer control system (1) and a camera (7), wherein the computer control system (1) is connected with the camera (7), a workbench (9) and a clamp (10), at least one position of the workbench (9) and the clamp (10) is adjusted according to the change situation of the gap distribution between the polishing target material (8) and the transparent workpiece (6) shot by the camera (7), and the gap between the polishing target material (8) and the transparent workpiece (6) is guaranteed to be a fixed value so that a focusing focus is always on the polishing target material (8).

6. The nanosecond laser-induced plasma composite femtosecond laser processing device according to claim 1, wherein: the transparent workpiece (6) and the polishing target (8) are arranged in an up-and-down spaced manner.

7. The nanosecond laser-induced plasma composite femtosecond laser processing device according to claim 6, wherein: the distance between the transparent workpiece (6) and the polishing target (8) is 0.05-0.5 mm.

8. The nanosecond laser-induced plasma composite femtosecond laser processing device according to claim 1, wherein: the material of the polishing target (8) is composed of elements with high atomic number.

9. The nanosecond laser-induced plasma composite femtosecond laser processing method is characterized in that: the method comprises the following steps: