A sapphire welding system based on ultrafast laser time domain shaping and a processing method thereof

Abstract

The application discloses a sapphire welding system based on ultrafast laser time domain shaping and a processing method thereof. The welding system comprises a laser emission system for emitting an ultrafast laser beam; a laser shaping system for shaping the ultrafast laser beam emitted by the laser emission system; a polarization light splitting system for performing polarization light splitting in the horizontal direction and the vertical direction on the laser beam output by the laser shaping system; a scanning galvanometer system for performing deflection control on the laser beam output by the polarization light splitting system, focusing the laser beam into a laser welding beam, and making the laser welding beam contact the interface between the sapphire and the metal material to be welded, so that the sapphire and the metal material are welded; and the ultrafast laser beam emitted by the laser emission system forms a laser welding light path after passing through the laser shaping system, the polarization light splitting system and the scanning galvanometer system. The double-pulse or multi-pulse sub-pulse energy obtained by time domain shaping is lower than that of a conventional ultrafast laser, the generation of thermal stress can be reduced, and the energy utilization rate is improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of ultrafast laser applications, and in particular to a sapphire welding system based on ultrafast laser time-domain shaping and a processing method. BACKGROUND

[0002] Welded parts of transparent crystals and metals have multiple properties such as strength, hardness, wear resistance, corrosion resistance, etc., and have a wide range of applications. Among the common transparent crystals, glass and sapphire are used more frequently. Sapphire is a transparent single crystal of aluminum oxide, also known as corundum, which has good mechanical properties, optical transparency, corrosion resistance, and high-temperature stability, and is widely used in high-speed aircraft infrared windows, high-temperature pressure sensor substrates, microwave device windows, and LED light-emitting devices. In the application of sapphire in these optical-mechanical devices, it is inevitable to face the problem of connection with itself or other metal materials. In order to ensure the optical properties and mechanical strength of these devices during application, the sapphire connection interface is required to have high strength and low residual stress, and also needs to have high connection precision.

[0003] Currently, the connection of sapphire and metal is mainly achieved by methods such as adhesive bonding, mechanical connection, diffusion welding, and active brazing. Among them, adhesive bonding is simple to operate and widely applicable, but has the disadvantages of easy outgassing, easy bleaching, easy softening, and easy aging of the adhesive. Mechanical connection involves complex processes such as drilling and has a complex connection structure, which to some extent affects the visual range of the window. The connection components of active brazing and diffusion welding have the advantages of high strength and good air tightness, but the welding process takes a long time, and usually requires the insertion of an intermediate layer or a filler layer to control the interface reaction or relieve residual stress, and pressure assistance is needed, which undoubtedly brings additional complexity to the connection process and greatly limits the popularization and application of this method. Therefore, although the above traditional connection methods can achieve good connection results, they still have certain limitations and cannot meet the needs of sapphire connection structures for high strength, low stress, high precision, and high efficiency.

[0004] In recent years, the rapid development of ultrafast laser provides a new powerful tool for precise and efficient connection of materials. In the existing literature PAN R, YANG D, ZHOU T, et al. Micro-welding of sapphire and metal by femtosecond laser [J]. Ceramics International, 2023, a method for connecting sapphire and invar alloy by ultrafast laser is provided, which uses a traditional unshaped ultrafast laser to weld sapphire and invar alloy. However, this method still has some technical problems, such as low processing efficiency, small process parameter window, thermal stress, and cracks at the connection interface. SUMMARY

[0005] In order to overcome the above technical problems, the purpose of the present application is to provide a sapphire welding system based on ultrafast laser time domain shaping and a processing method, to solve the technical problems of low processing efficiency, small process parameter window and thermal stress in the prior art.

[0006] The present application provides the following technical solutions:

[0007] First aspect

[0008] The present application provides a sapphire welding system based on ultrafast laser time domain shaping, which comprises:

[0009] A laser emission system comprising an ultrafast laser (1) for emitting an ultrafast laser beam;

[0010] A laser shaping system for shaping the ultrafast laser beam emitted by the laser emission system, the shaping including shaping of pulse sequence interval, laser power, pulse width and repetition frequency;

[0011] A polarization splitting system for splitting the laser beam output by the laser shaping system in horizontal and vertical directions to construct a first beam optical path and a second beam optical path, so that the first beam and the second beam have an optical path difference;

[0012] A scanning galvanometer system for deflecting control of the laser beam output by the polarization splitting system, focusing into a laser welding beam, to the contact interface of the sapphire and metal material to be welded, and welding the sapphire and metal material;

[0013] The ultrafast laser beam emitted by the laser emission system passes through the laser shaping system, the polarization splitting system and the scanning galvanometer system to form a laser welding optical path;

[0014] An imaging system for observing the contact interface of the sample to be welded.

[0015] In the above embodiment, the scanning galvanometer system is used to deflect the laser beam output by the polarization beam splitting system in the plane position, so as to change the irradiation position of the laser beam and focus it into a laser welding beam.

[0016] According to some embodiments, the ultrafast laser (1) emits femtosecond pulse laser or picosecond pulse laser; the laser shaping system comprises, in sequence through optical path connection, a pulse shaper (2), a laser beam expander (3), a wave plate (4), a first positioning light hole (5), a first total reflection mirror (6) and a second total reflection mirror (7), the pulse shaper (2) is used for shaping the number of sub-pulses and the interval of sub-pulses of the pulse; the laser beam expander (3) is used for expanding the beam; the wave plate (4) is used for decomposing the vibration of the laser beam into two components perpendicular to the optical axis and parallel to the optical axis; the first positioning light hole (5), the first total reflection mirror (6) and the second total reflection mirror (7) are used for outputting the laser beam.

[0017] The polarization beam splitting system comprises a polarization beam splitter (8), which divides the laser beam into a first beam path polarized in the horizontal direction and a second beam path polarized in the vertical direction, the first beam path comprises a path distance displacement stage (11) for adjusting the path distance, and a third total reflection mirror (9) and a fourth total reflection mirror (10) arranged above the path distance displacement stage (11); the second beam path comprises a fifth total reflection mirror (12) and a sixth total reflection mirror (13), the beam passing through the first beam path and the beam passing through the second beam path have an optical path difference, the first and second beam paths are combined by a first half-transmission half-reflection mirror (14) to form a combined laser beam.

[0018] In the above embodiment, the time interval of the sub-pulse is in the order of nanoseconds; the expansion of the beam by the laser beam expander refers to expanding the diameter of the straight input beam to a larger collimated output beam.

[0019] According to some embodiments, the scanning galvanometer system comprises, in sequence through optical path connection, a third half-transmission half-reflection mirror (16), a second positioning light hole (20), a scanning galvanometer (21) and a displacement workbench (22) for placing a sample to be welded, the scanning galvanometer (21) is used for deflecting control of the irradiation position of the combined laser beam, and the combined laser beam is focused to the contact interface of the sample to be welded for welding.

[0020] According to some embodiments, the imaging system comprises a scattering light source (17), a second half-transmission half-reflection mirror (15), an imaging lens (18) and a camera (19) connected in sequence through an optical path; the scattering light source (17) emits scattering light, which is irradiated to the contact interface of the displacement workbench (22) after being passed through the second half-transmission half-reflection mirror (15), the third half-transmission half-reflection mirror (16), the second positioning light hole (20) and the scanning galvanometer (21), thereby providing illumination for the sample to be welded and constituting an illumination optical path; the light on the welding interface of the sample to be welded is sequentially passed through the scanning galvanometer (21), the second positioning light hole (20), the third half-transmission half-reflection mirror (16), the second half-transmission half-reflection mirror (15), imaged on the imaging lens (18) and collected by the camera (19).

[0021] Second aspect

[0022] The application also provides a processing method based on the above-mentioned sapphire welding system based on ultrafast laser time-domain shaping, which comprises the following steps:

[0023] S1: surface pretreatment of sapphire and metal materials to be welded: double-sided mechanical polishing and double-sided polishing are performed on the sapphire to be connected; single-sided step-by-step mechanical polishing is performed on the metal material to be welded, and then polishing is performed on a polishing machine until there are no large scratches under a metallographic microscope; the treated sample to be welded is cleaned with ultrasonic anhydrous ethanol and dried;

[0024] S2: fixation and placement of sapphire and metal materials to be welded: the sapphire and the metal material after surface pretreatment are contacted and fixed and clamped in a clamp, and the clamp and the sample to be welded are placed on the displacement workbench (22).

[0025] S3: time-domain shaping of ultrafast laser connection: the ultrafast laser (1), the pulse shaper (2), the polarization beam splitter (8) and the optical path distance displacement table (11) are adjusted to optimize the pulse sequence interval, the laser power, the pulse width and the repetition frequency; the scanning speed, the scanning path and the scanning pitch are adjusted by adjusting the scanning galvanometer (21) and the displacement workbench (22), so that the laser welding beam formed after shaping is focused on the contact interface of the sapphire and the metal material, and is observed by the camera (19).

[0026] According to some embodiments, the metal material to be welded is selected from one of invar, copper, Ti and Ti alloy, stainless steel and various Fe-Ni alloys; the sapphire to be welded is selected from commercially available double-sided polished sapphire.

[0027] According to some embodiments, in the S3 step, the scanning path has a certain pattern, and the pattern is selected from any one of a cross-shaped pattern, a parallel line pattern, a concentric rectangular pattern, a concentric circle pattern and a spiral line pattern.

[0028] According to some embodiments, in the S3 step, the joint form of the sapphire and the metal material is selected from any one of the following: stacking, overlapping and butting.

[0029] According to some embodiments, in the S3 step, the sub-pulse interval of the laser welding beam is 0-16 ns, and the sub-pulse energy ratio is (0.1-10):1.

[0030] Compared with the prior art, the present application has the following beneficial effects:

[0031] The sapphire welding system and the processing method based on ultrafast laser time-domain shaping provided by the present application have the following advantages: the sub-pulse energy of the double-pulse or multi-pulse obtained by time-domain shaping is lower than that of the conventional ultrafast laser, which can reduce the generation of thermal stress and improve the energy utilization rate. Compared with the conventional brazing and diffusion welding, the present application does not need to heat the whole sample, which reduces the material damage and improves the welding efficiency. In addition, due to the high concentration of energy density, the present application can realize high-precision welding of the material. BRIEF DESCRIPTION OF DRAWINGS

[0032] Figure 1 The structural schematic diagram of the embodiment one provided by the present application.

[0033] Figure 2 The flowchart of the processing method provided by the present application.

[0034] Figure 3 The cross intersection path of laser scanning when welding the sapphire and the metal material provided by the present application.

[0035] Figure 4 The macroscopic morphology comparison diagram of the welded piece of the shaped laser beam and the welded piece of the conventional single-pulse beam provided by the present application.

[0036] In the drawings, the reference signs are as follows:

[0037] 1, ultrafast laser; 2, pulse shaper; 3, laser expander; 4, wave plate; 5, first positioning light hole; 6, first total reflection mirror; 7, second total reflection mirror; 8, polarization beam splitter; 9, third total reflection mirror; 10, fourth total reflection mirror; 11, light path distance displacement table; 12, fifth total reflection mirror; 13, sixth total reflection mirror; 14, first half-transmission half-reflection mirror; 15, second half-transmission half-reflection mirror; 16, third half-transmission half-reflection mirror; 17, scattering light source; 18, imaging lens; 19, camera; 20, second positioning light hole; 21, scanning galvanometer; 22, displacement workbench. DETAILED DESCRIPTION

[0038] The present invention will now be described in detail with reference to embodiments and accompanying drawings. However, it should be understood that the embodiments and drawings are for illustrative purposes only and do not constitute any limitation on the scope of protection of the present invention. All reasonable modifications and combinations included within the inventive spirit of the present invention fall within the scope of protection of the present invention.

[0039] The technical solution of the present invention will now be described in detail with reference to the accompanying drawings.

[0040] Example 1:

[0041] like Figure 1 An embodiment of a welding system based on ultrafast laser time-domain shaping is shown. This welding system welds sapphire and metal materials, and includes: an ultrafast laser 1 for emitting ultrafast laser light; a pulse shaper 2 for performing nanosecond-level time-domain shaping on the pulse; a laser beam expander 3 for increasing the diameter of the laser beam; a waveplate 4 for decomposing the laser vibration emitted by the ultrafast laser 1 into two components perpendicular to the optical axis and parallel to the optical axis; after the laser beam enters the polarization beam splitter 8 through a first positioning aperture 5, a first total reflection mirror 6, and a second total reflection mirror 7, the horizontal and vertical polarization of the laser beam are separated, forming the L1 beam path and the L2 beam path, respectively; L The L1 beam path includes a third total reflection mirror 9 and a fourth total reflection mirror 10 mounted on the optical path distance displacement stage 11; the L2 beam path includes a fifth total reflection mirror 12 and a sixth total reflection mirror 13. Through different optical paths, beams L1 and L2 generate an optical path difference; beams L1 and L2 are combined by the first semi-transparent and semi-reflective mirror 14, and the combined beam is deflected by the third semi-transparent and semi-reflective mirror 16, the second positioning aperture 20 and the scanning galvanometer 21, and focused on the displacement stage 22 for welding sapphire and metal materials; while the scattering light source 17, the second semi-transparent and semi-reflective mirror 15, the imaging lens 18 and the camera 19 are used to observe the welding operation of the displacement stage 22.

[0042] Specifically, the femtosecond or picosecond pulsed laser emitted by the ultrafast laser 1 sequentially passes through the pulse shaper 2, the laser beam expander 3, the wave plate 4, the first positioning light hole 5, the first total reflection mirror 6, the second total reflection mirror 7, and then is divided into two laser beams L1 and L2 along two directions at the polarizing beam splitter 8, the wave plate 4 is used to decompose the laser vibration emitted by the ultrafast laser 1 into two components perpendicular to the optical axis and parallel to the optical axis, the polarizing beam splitter 8 is used to separate the horizontal polarization and the vertical polarization of the laser beam, and the wave plate 4 and the polarizing beam splitter 8 together form an energy distribution system, which can freely adjust and control the energy distribution of the laser beams L1 and L2; the light beam L1 passes through the third total reflection mirror 9 and the fourth total reflection mirror 10 located on the optical path distance displacement table 11, and the optical path difference between the light beams L1 and L2 is generated by controlling the movement of the optical path distance displacement table 11; the L2 passes through the fifth total reflection mirror 12 and the sixth total reflection mirror 13; the light beams L1 and L2 are combined at the first half-transmission half-reflection mirror 14, then pass through the third half-transmission half-reflection mirror 16, the second positioning light hole 20 and the scanning galvanometer 21, and finally are focused on the contact interface between the sapphire and the metal sample on the workbench 22 to form a laser welding beam, so as to weld the sapphire and the metal sample, and a laser welding light path is formed, and the metal material is selected from invar alloy. In addition, the sapphire welding system based on the ultrafast laser time domain shaping can also be provided with a pulse shaper at the emission port of the ultrafast laser 1 to assist in regulating and controlling the pulse sequence sub-pulse interval and the sub-pulse energy distribution ratio of the laser beam. The scattering light source 17, the second half-transmission half-reflection mirror 15, the imaging lens 18 and the camera 19 are used for real-time observation of the welding operation of the displacement workbench 22. The light emitted by the scattering light source 17 is scattering light, which sequentially passes through the second half-transmission half-reflection mirror 15, the third half-transmission half-reflection mirror 16, the second positioning light hole 20 and the scanning galvanometer 21, and then irradiates on the welding position of the displacement workbench 22, and this light path constitutes an illumination light path; the imaging light of the welding position of the sample to be welded sequentially passes through the scanning galvanometer 21, the second positioning light hole 20, the third half-transmission half-reflection mirror 16, the second half-transmission half-reflection mirror 15, and then is captured by the camera 19 after forming at the imaging lens 18, and this light path constitutes an imaging light path. The laser welding light path and the illumination light path coincide after passing through the third half-transmission half-reflection mirror 16, and the imaging light path and the illumination light path coincide between the welding position and the second half-transmission half-reflection mirror 15, and the sample to be welded is clamped and fixed on the displacement workbench 22 by a clamp.

[0043] The application also provides a processing method of the sapphire welding system based on the ultrafast laser time domain shaping. Figure 2 The processing method comprises the following steps:

[0044] S1: Surface pretreatment of sapphire and metal materials to be welded: the sapphire to be connected is mechanically polished on both sides, and then polished on both sides; the metal material to be welded is mechanically polished on one side, and then polished on the polishing machine to have no large scratches under the metallographic microscope. The treated sapphire and metal material to be welded are cleaned with ultrasonic anhydrous ethanol and dried.

[0045] S2: Fixing and placing of sapphire and metal materials to be welded: the sapphire and metal material after surface pretreatment are contacted and fixed in a clamp, and the clamp and the sample to be welded are placed on the displacement workbench 22.

[0046] S3: Time-domain shaping ultrafast laser connection: the pulse sequence interval, laser power, pulse width and repetition frequency are optimized by adjusting the ultrafast laser 1, pulse shaper 2, polarization beam splitter 8 and optical path distance displacement table 11. The scanning speed, scanning path and scanning spacing are adjusted by adjusting the scanning galvanometer and displacement workbench 22, so that the shaped ultrafast laser is focused on the contact interface of sapphire and metal material. The processing phenomenon is observed by the camera 19.

[0047] In the S1 step, the metal material used in addition to invar alloy can be selected from copper, Ti and Ti alloy, stainless steel and various Fe-Ni alloys, and the sapphire material to be welded is selected from commercially available double-sided polished sapphire.

[0048] In the S3 step, the laser scanning path is a special shape, including: cross type, parallel line type, concentric rectangular type, concentric circle type, spiral line type, etc. Figure 3 As shown in the cross type path of laser scanning.

[0049] In the S3 step, the sapphire and invar alloy joint forms are various, including stacking, lap joint and butt joint.

[0050] In the S3 step, the sub-pulse interval of the laser welding beam is 0-16 ns, and the sub-pulse energy ratio is (0.1-10):1.

[0051] Example two

[0052] In this embodiment, the femtosecond laser used is CARBIDE CB3-40W, the central wavelength of the emitted laser beam is 257nm, 343nm, 515nm and 1064nm, the pulse width is 263fs-5ps, the repetition frequency is 1KHz-2MHz, the maximum single pulse energy is 400μJ, the maximum average output power is 40W, and the light field distribution is Gaussian distribution. The repeated positioning accuracy of the displacement workbench in x, y and z axes is ±0.5μm, ±0.5μm and ±0.2μm, respectively. The camera 19 used is an industrial grade CCD.

[0053] In the embodiment, the specific processing steps are as follows:

[0054] S1: surface pretreatment of the material to be welded: the invar alloy to be connected is mechanically polished on one side by sandpaper in stages, and then the polished invar alloy is polished on a polishing machine using a polishing cloth, and the invar alloy surface is polished to have no large scratches under a metallographic microscope; the sapphire to be connected is mechanically polished on both sides by a diamond grinding disc in stages, and is polished on both sides on a polishing machine, and the specific polishing method is as follows: first, the sapphire is polished for 10-20 min using a diamond polishing agent, and then the sapphire is polished for 5-10 min using clean water. Then the sapphire and the invar alloy after surface pretreatment are placed in anhydrous ethanol, and are cleaned by ultrasonic waves at a frequency of 100 Hz for 5-10 min, and then the sapphire and the invar alloy after cleaning are taken out by tweezers and are dried by a hair dryer. The sapphire to be connected can also be a commercially available double-sided polished sapphire; the metal material to be connected can be copper, Ti and Ti alloy, stainless steel, and various Fe-Ni alloys.

[0055] S2: fixation and placement of the sample to be welded: the pretreated sapphire and invar alloy are stacked in a clamp, and the clamp is used to make the sapphire and invar alloy materials closely contact; in addition, the gap between the sapphire and the metal material can be adjusted by adjusting the clamping force of the clamp. In order to ensure the precision and strength of the ultrafast laser welding of the sapphire and the metal, the clamping force of the clamp is adjusted so that Newton's rings appear when the sapphire and the metal are stacked, and at this time the gap between the sapphire and the invar alloy is less than 1 μm. At the same time, the scattering light source 17 is turned on, and the processing process is detected by means of the camera 19.

[0056] S3: ultrafast laser time-domain shaping: the optical path components are connected in order Figure 1 , the focus position of the ultrafast laser 1 is adjusted so that the focus of the scanning galvanometer 21 is focused on the contact surface position of the sapphire and the invar alloy. The wave plate 4 and the polarization beam splitter 8 are adjusted to adjust the ultrafast laser energy, the position of the optical path distance displacement table 11 is adjusted so that the sub-pulse interval is 400 fs, or the sub-pulse interval is directly controlled in nanosecond level by using the pulse shaper 2, and then the light beam is irradiated to the interface between the sapphire and the invar alloy through the above shaped optical path to realize the connection of the two materials, and at the same time, the scattering light source 17 is used to capture the processing picture by means of the imaging lens 18 and the camera 19 during the processing.

[0057] Under the same conditions of other adjustments, the traditional single-pulse light beam connector and the shaped light beam connector are observed under a light focusing microscope, and after the shaped light beam welding processing, the connection interface morphology is good and no defects such as micro-cracks caused by thermal stress are found, such as Figure 4 , a comparison chart of the morphology of the processed workpiece under a scale of 500 um is shown, Figure 4a is a non-shaping beam processing workpiece figure, and obvious cracks appear on the workpiece; Figure 4 b is a shaping beam processing workpiece, and no cracks are found on the workpiece.

[0058] The above embodiments are only preferred embodiments of the present application, and the protection scope of the present application is not limited to the above embodiments. Any technical scheme falling within the concept of the present application belongs to the protection scope of the present application. It should be pointed out that improvements and refinements made by ordinary skilled in the art without departing from the principles of the present application should also be considered as the protection scope of the present application.

Claims

1. A sapphire welding system based on ultrafast laser time-domain shaping, comprising: a laser emission system comprising an ultrafast laser (1) for emitting an ultrafast laser beam; a laser shaping system for shaping the ultrafast laser beam emitted by the laser emission system, the shaping comprising shaping of pulse sequence interval, laser power, pulse width and repetition frequency; a polarization splitting system for splitting the laser beam output by the laser shaping system in horizontal and vertical directions to construct a first beam optical path and a second beam optical path, so that the first beam and the second beam have an optical path difference; a scanning galvanometer system for deflection control of the laser beam output by the polarization splitting system, focusing into a laser welding beam, to the contact interface of the sapphire and metal material to be welded, for welding the sapphire and metal material; the ultrafast laser beam emitted by the laser emission system forms a laser welding optical path after passing through the laser shaping system, the polarization splitting system and the scanning galvanometer system; an imaging system for observing the contact interface of the sample to be welded; the ultrafast laser (1) emits femtosecond pulse laser or picosecond pulse laser; the laser shaping system comprises a pulse shaper (2), a laser beam expander (3), a wave plate (4), a first positioning light hole (5), a first total reflection mirror (6) and a second total reflection mirror (7) connected in sequence by optical path, the pulse shaper (2) is used for shaping the number of sub-pulses and the interval of sub-pulses; the laser beam expander (3) is used for expanding the beam; the wave plate (4) is used for decomposing the laser beam vibration into two components perpendicular to the optical axis and parallel to the optical axis; the first positioning light hole (5), the first total reflection mirror (6) and the second total reflection mirror (7) are used for outputting the laser beam; the polarization splitting system comprises a polarization splitter (8), the polarization splitter (8) divides the laser beam into a first beam optical path polarized in the horizontal direction and a second beam optical path polarized in the vertical direction, the first beam optical path comprises an optical path distance displacement table (11) for adjusting the optical path distance, and a third total reflection mirror (9) and a fourth total reflection mirror (10) arranged above; the second beam optical path comprises a fifth total reflection mirror (12) and a sixth total reflection mirror (13), the beam passing through the first beam optical path and the beam passing through the second beam optical path have an optical path difference, the first and second beam optical paths are combined by a first half-transmission half-reflection mirror (14) to form a combined laser beam.

2. The ultrafast laser time-domain shaping based sapphire welding system according to claim 1, characterized in that: the scanning galvanometer system comprises a third half-transmission half-reflection mirror (16), a second positioning light hole (20), a scanning galvanometer (21) and a displacement workbench (22) for placing the sample to be welded connected in sequence by optical path, the scanning galvanometer (21) is used for deflection control of the irradiation position of the combined laser beam and focusing to the contact interface of the sample to be welded for welding.

3. The ultrafast laser time-domain shaping based sapphire welding system according to claim 2, characterized in that: The imaging system comprises a scattering light source (17), a second half-transmission half-reflection mirror (15), an imaging lens (18) and a camera (19) connected in sequence through an optical path; the scattering light source (17) emits scattering light, which is irradiated to the contact interface of the displacement workbench (22) after being reflected by the second half-transmission half-reflection mirror (15), the third half-transmission half-reflection mirror (16), the second positioning light hole (20) and the scanning galvanometer (21), thereby providing illumination for the welding sample to form an illumination light path; the light on the welding interface of the welding sample passes through the scanning galvanometer (21), the second positioning light hole (20), the third half-transmission half-reflection mirror (16), the second half-transmission half-reflection mirror (15) in sequence, and is imaged on the imaging lens (18) to be collected by the camera (19).

4. The method of claim 3, wherein the method is a method of processing a sapphire welding system based on ultrafast laser time-domain shaping. The method comprises the following steps: S1: surface pretreatment of the sapphire and metal material to be welded: the sapphire to be connected is mechanically polished on both sides, and then polished on both sides; The metal material to be welded is mechanically polished on one side in stages, and then polished on a polishing machine to have no large scratches under a metallographic microscope; the treated welding sample is cleaned by ultrasonic ethanol and dried; S2: fixation and placement of the sapphire and metal material to be welded: the sapphire and metal material after surface pretreatment are contacted and fixed and clamped in a clamp, and the clamp and the welding sample are placed on the displacement workbench (22); S3: time-domain shaping of the ultrafast laser: the ultrafast laser (1), the pulse shaper (2), the polarization beam splitter (8) and the optical path distance displacement table (11) are adjusted to optimize the pulse sequence interval, the laser power, the pulse width and the repetition frequency; the scanning speed, the scanning path and the scanning pitch are adjusted by adjusting the scanning galvanometer (21) and the displacement workbench (22), so that the laser welding beam formed after shaping is focused on the contact interface of the sapphire and the metal material, and observed by the camera (19).

5. The method of claim 4, wherein: The metal material to be welded is selected from one of invar alloy, copper, Ti and Ti alloy, stainless steel and various Fe-Ni alloys; the sapphire to be welded is selected from commercially available double-side polished sapphire.

6. The method of claim 4, wherein: In the S3 step, the scanning path has a certain shape, and the shape is selected from any one of cross type, parallel line type, concentric rectangular type, concentric circle type and spiral line type.

7. The method of claim 4, wherein: In the S3 step, the sapphire and metal material joint form is selected from any one of stacking, lap joint and butt joint.

8. The method of claim 4, wherein: In the S3 step, the sub-pulse interval of the laser welding beam is 0-16 ns, and the sub-pulse energy ratio is (0.1-10):1.

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