Large-spot ultraviolet high-power picosecond laser

Abstract

The invention relates to a large-light-spot ultraviolet high-power picosecond laser which comprises a seed source, a power amplification system, a beam expanding system, a laser frequency conversion system and a shaper. The seed source is used for generating an infrared beam; the power amplification system, the beam expanding system, the laser frequency conversion system and the shaper are sequentially arranged in the infrared beam propagation direction. The power amplification system is used for performing power amplification on the infrared light beams emitted by the seed source; the beam expanding system is used for adjusting the divergence angle of the infrared light beam so as to improve the size of a light spot formed at the laser frequency conversion system; the laser frequency conversion system is used for converting the infrared light beam into an ultraviolet light beam; and the shaper is used for shaping the ultraviolet light beams and then outputting the ultraviolet light beams. According to the invention, large ultraviolet light spots are realized, the peak power density of an ultraviolet device can be effectively reduced, the service life of the ultraviolet device can be effectively prolonged, and the number of ultraviolet beam expanders at the rear end can be reduced, so that the later use and maintenance cost is reduced; the structure is simple and the cost is low.

Description

Technical Field

[0001] The invention relates to the technical field of lasers, and in particular to a large-spot ultraviolet high-power picosecond laser. Background Art

[0002] Due to its short wavelength and narrow pulse width, UV picosecond lasers exhibit excellent cold processing effects and are widely used in ultra-precision processing in consumer electronics, display panels, new energy, PCB, biomedicine, aerospace and other industries.

[0003] For ultraviolet high-power picosecond lasers, the fatal problem is the life of the core components of the ultraviolet part, including ultraviolet crystals, ultraviolet reflectors, and shaping devices. There are some methods to extend the life of ultraviolet components, such as using uncoated corner crystals, point-changing design, and automatic optimization. However, there are still certain disadvantages, such as high requirements for electronic control design, and the need for regular maintenance of back-end components, which is costly. The above problems need to be solved urgently. Summary of the invention

[0004] The invention discloses a large-spot ultraviolet high-power picosecond laser, aiming to solve the technical problems existing in the prior art.

[0005] The present invention adopts the following technical solutions: The invention provides a large-spot ultraviolet high-power picosecond laser, which comprises a seed source, a power amplification system, a beam expansion system, a laser frequency conversion system and a shaper; the seed source is used to generate an infrared light beam; the power amplification system, the beam expansion system, the laser frequency conversion system and the shaper are arranged in sequence along the propagation direction of the infrared light beam; the power amplification system is used to amplify the power of the infrared light beam emitted by the seed source; the beam expansion system is used to adjust the divergence angle of the infrared light beam to increase the size of the light spot formed at the laser frequency conversion system; the laser frequency conversion system is used to convert the infrared light beam into an ultraviolet light beam; the shaper is used to shape the ultraviolet light beam and then output it.

[0006] In the large-spot ultraviolet high-power picosecond laser of the present invention, the beam expansion system is an infrared beam expansion system, and includes a positive lens, a negative lens and a base; the negative lens and the positive lens are arranged in sequence along the beam propagation direction, and can be installed on the base close to or far away from each other along the beam propagation direction.

[0007] In the large-spot ultraviolet high-power picosecond laser of the present invention, the laser frequency conversion system includes a frequency doubling crystal and a sum frequency crystal; the frequency doubling crystal and the sum frequency crystal are arranged in sequence along the propagation direction of the light beam; the frequency doubling crystal is used to convert part of the input infrared light into green light; the sum frequency crystal is used to convert the output light of the frequency doubling crystal into ultraviolet light.

[0008] In the large-spot ultraviolet high-power picosecond laser of the present invention, the power amplification system includes an amplifier and an acousto-optic modulator arranged in sequence along the propagation direction of the light beam; the amplifier is used to amplify the power of the infrared light beam emitted by the seed source; the acousto-optic modulator is used to control the power of the light beam output by the amplification system.

[0009] The large-spot ultraviolet high-power picosecond laser of the present invention also includes a beam adjustment system; the beam adjustment system is used to adjust the beam diameter of the infrared beam at the acousto-optic modulator to be smaller than the effective aperture of the acousto-optic modulator.

[0010] In the large-spot ultraviolet high-power picosecond laser of the present invention, the distance between the power amplification system and the laser frequency conversion system is adjustable.

[0011] The large-spot ultraviolet high-power picosecond laser of the present invention also includes a first reflector and a second reflector; the light beam output by the power amplification system is reflected into the beam expansion system; the second reflector is used to reflect the light beam output by the beam expansion system into the laser frequency conversion system; the second reflector and the first reflector are configured to be able to move along the propagation direction of the incident light of the first reflector.

[0012] In the large-spot ultraviolet high-power picosecond laser of the present invention, the distance between the laser frequency conversion system and the shaper is adjustable.

[0013] The large-spot ultraviolet high-power picosecond laser of the present invention also includes a third reflector and a fourth reflector; the third reflector is used to reflect the light beam output by the laser frequency conversion system into the fourth reflector; the fourth reflector is used to reflect the light beam output by the third reflector into the shaper; the fourth reflector and the third reflector are configured to be able to move along the propagation direction of the incident light of the third reflector.

[0014] The large-spot ultraviolet high-power picosecond laser of the present invention further comprises a window mirror; the window mirror is arranged on the light-emitting side of the shaper.

[0015] The technical solution adopted by the present invention can achieve the following beneficial effects: The present invention mainly provides a large-spot ultraviolet high-power picosecond laser, which is based on emitting an infrared light beam with a seed source, amplifying the power through a power amplifier system, and adjusting the divergence angle of the light beam with a beam expansion system to increase the diameter of the light spot formed by the light beam at the laser frequency conversion system, and then converting the infrared light into ultraviolet light through the laser frequency conversion system, and finally outputting it after being shaped by a shaper, thereby realizing a large ultraviolet light spot, being able to effectively reduce the peak power density of the ultraviolet device, and effectively extending the life of the ultraviolet device, and being able to reduce the rear-end ultraviolet beam expander, thereby reducing the cost of later use and maintenance; and the structure is simple and the cost is low. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following briefly introduces the drawings required for describing the embodiments, which constitute a part of the present invention. The exemplary embodiments of the present invention and their descriptions explain the present invention and do not constitute improper limitations on the present invention. In the drawings: Figure 1 It is a structural schematic diagram of a large-spot ultraviolet high-power picosecond laser of the present invention; Figure 2 It is a schematic structural diagram of the beam expansion system of the present invention.

[0017] Description of reference numerals: 1. Seed source; 2. Power amplification system; 21. Amplifier; 22. Acousto-optic modulator; 23. Beam adjustment system; 3. Beam expansion system; 31. Positive lens; 32. Negative lens; 33. Base; 4. Laser frequency conversion system; 41. Frequency doubling crystal; 42. Sum frequency crystal; 5. Shaper; 6. First reflector; 7. Second reflector; 8. Third reflector; 9. Fourth reflector; 10. Window mirror. DETAILED DESCRIPTION

[0018] In order to make the purpose, technical solution and advantages of the present invention clearer, the technical solution of the present invention will be clearly and completely described below in conjunction with the specific embodiments of the present invention and the corresponding drawings. In the description of the present invention, it should be noted that the term "or" is usually used in the sense of including "and / or", unless the content clearly indicates otherwise.

[0019] In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or a magnetic connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal connection of two elements. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances. In addition, in the description of this application, the terms "first", "second", etc. are only used to distinguish the description, and cannot be understood as indicating or implying relative importance. In the description of the present invention, the meaning of "multiple" is at least two, such as two, three or more, etc., unless otherwise clearly and specifically limited.

[0020] Obviously, the described embodiments are only some embodiments of the present invention, not all 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.

[0021] In order to solve the problems existing in the prior art, the embodiments of the present application provide a large-spot ultraviolet high-power picosecond laser.

[0022] A large spot UV high power picosecond laser, such as Figure 1 As shown, it includes a seed source 1, a power amplification system 2, a beam expansion system 3, a laser frequency conversion system 4 and a shaper 5; the seed source 1 is used to generate an infrared light beam; the power amplification system 2, the beam expansion system 3, the laser frequency conversion system 4 and the shaper 5 are arranged in sequence along the propagation direction of the infrared light beam; the power amplification system 2 is used to amplify the power of the infrared light beam emitted by the seed source 1; the beam expansion system 3 is used to adjust the divergence angle of the infrared light beam to increase the spot size formed at the laser frequency conversion system 4; the laser frequency conversion system 4 is used to convert the infrared light beam into an ultraviolet light beam; the shaper 5 is used to shape the ultraviolet light beam and output it externally, and the shaper 5 is used to adjust the spot size and astigmatism parameters.

[0023] The large-spot ultraviolet high-power picosecond laser of the present invention is based on emitting an infrared light beam with a seed source 1, amplifying the power through a power amplifier system 2, adjusting the divergence angle of the light beam with a beam expansion system 3 to increase the diameter of the light beam spot formed at a laser frequency conversion system 4, and then converting the infrared light into ultraviolet light through the laser frequency conversion system 4, and finally outputting it after being shaped by a shaper 5; a large ultraviolet light spot is achieved, the peak power density of the ultraviolet device can be effectively reduced, the service life of the ultraviolet device can be effectively extended, and the rear-end ultraviolet beam expander can be reduced, thereby reducing the cost of later use and maintenance; and the structure is simple and the cost is low.

[0024] In some preferred embodiments, the beam expansion system 3 can be composed of positive and negative lenses; or composed of 1 lens and 2 cylindrical lenses; or composed of multiple cylindrical lenses, without specific limitation, as long as it can achieve the function of expanding the beam and increasing the divergence angle of the light beam.

[0025] In some preferred embodiments, the beam expansion system 3 is an infrared beam expansion system, such as Figure 2 As shown, it includes a positive lens 31, a negative lens 32 and a base 33; the negative lens 32 and the positive lens 31 are arranged in sequence along the direction of light beam propagation, and can be installed on the base 33 close to or away from each other along the direction of light beam propagation; taking the movable positive lens 31 as an example, if a sliding groove is set in the base 33, the positive lens 31 can slide in the groove, which is convenient for changing the spacing between the positive lens 31 and the negative lens 32 to achieve the control of the divergence angle, thereby achieving the purpose of adjusting the beam expansion spacing and changing the divergence angle, and realizing the control of the infrared spot, such as shortening the beam expansion spacing, the divergence angle can be increased, the infrared spot can be increased, and lengthening the beam expansion spacing can make the divergence angle smaller, and the infrared spot can be smaller. Specifically, the focal length of the negative lens 32 can be selected as negative 20mm, the focal length of the positive lens 31 can be selected as positive 60mm, and the beam expansion spacing is about 43mm.

[0026] In some preferred embodiments, the laser frequency conversion system 4 includes a frequency doubling crystal 41 and a sum frequency crystal 42; the frequency doubling crystal 41 and the sum frequency crystal 42 are arranged in sequence along the propagation direction of the light beam; the frequency doubling crystal 41 is used to convert the input infrared light part into green light; the sum frequency crystal 42 is used to convert the output light of the frequency doubling crystal 41 into ultraviolet light; based on the conversion of infrared light into ultraviolet light by the combination of the frequency doubling crystal 41 and the sum frequency crystal 42, the conversion efficiency can be improved; further preferably, it includes a plurality of frequency doubling crystals 41 of different lengths and a plurality of sum frequency crystals 42 of different lengths, so as to adjust the length of the frequency doubling crystal 41 and the sum frequency crystal 42 in the system according to the spot size, so as to ensure that the laser frequency conversion system 4 has a high conversion efficiency, reduce power loss, and achieve the best ultraviolet light output, such as the power of ultraviolet light and the quality of the spot. Optionally, the length of the frequency doubling crystal 41 can be 10mm, 15mm, 20mm, etc., which is determined according to the process requirements; the length of the sum frequency crystal 42 is the same as that of the frequency doubling crystal, which will not be repeated.

[0027] In some preferred embodiments, the power amplification system 2 includes an amplifier 21 and an acousto-optic modulator 22, such as model AM3, which are arranged in sequence along the propagation direction of the light beam; the amplifier 21 is used to amplify the power of the infrared light beam emitted by the seed source 1; the acousto-optic modulator 22 is used to control the power of the light beam output by the amplifier 21; through the cooperation of the amplifier 21 and the acousto-optic modulator 22, power amplification is achieved while outputting different powers; preferably, Bragg diffraction is performed with the acousto-optic modulator 22, and the first-order diffraction light is output, thereby achieving output of different powers; wherein, the amplifier 21 can be selected as an optical path structure that can achieve infrared light power amplification, and there is no restriction here.

[0028] In some preferred embodiments, a beam adjustment system 23 is further included; the beam adjustment system 23 is used to adjust the beam diameter of the infrared light beam at the AOM 22 to be smaller than the effective aperture of the AOM 22; specifically, the beam adjustment system 23 can be a beam expansion system or a beam reduction system, which is selected according to the working conditions; based on the setting of the beam adjustment system 23, the diameter of the light beam entering the AOM 22 is adjusted, so that the diffraction efficiency of the AOM 22 can be improved.

[0029] In some preferred embodiments, the distance between the power amplification system 2 and the laser frequency conversion system 4, or the beam expansion system 3 and the laser frequency conversion system 4 is adjustable; based on the adjustable distance between the two, that is, the adjustable optical path length, the size of the light spot formed at the laser frequency conversion system 4 can be adjusted to avoid the light spot being too large or too small, thereby increasing the adjustment range of the light spot; in particular, it can avoid the divergence angle in the light beam system being too large, so as to facilitate the shaping and collimation processing of the shaper 5.

[0030] As an implementation method, an optical path folding system may be provided between the power amplification system 2 and the laser frequency conversion system 4 or between the beam expansion system 3 and the laser frequency conversion system 4, such as providing multiple reflectors or other folding systems capable of extending the optical path.

[0031] As a second implementation, the power amplification system 2 and / or the laser frequency conversion system 4 may be configured to be slidably connected to a mounting base (not shown), or the beam expansion system 3 and the laser frequency conversion system 4 may be configured to be slidably connected to a mounting base (not shown), so as to change the distance between the power amplification system 2 and the laser frequency conversion system 4 or the beam expansion system 3 and the laser frequency conversion system 4; As a third implementation method, the outer shell for installing the power amplification system 2 or the beam expansion system 3 and the laser frequency conversion system 4 can be configured to be retractable, and the power amplification system 2 or the beam expansion system 3 and the laser frequency conversion system 4 can be respectively arranged on two parts that can be relatively retracted to change the distance between them when the outer shell is retracted.

[0032] Of course, other methods that can adjust the distance between the power amplification system 2 and the laser frequency conversion system 4 may also be selected, which is not limited here.

[0033] Preferably, it also includes a first reflector 6 and a second reflector 7; the first reflector 6 is used to reflect the light beam output by the power amplifier system 2 into the beam expansion system 3; the second reflector 7 is used to reflect the light beam output by the beam expansion system 3 into the laser frequency conversion system 4, preferably, the light reflected by the second reflector 7 is parallel to the incident light of the first reflector 6; the second reflector 7 and the first reflector 6 are configured to be able to move along the propagation direction of the incident light of the first reflector 6; based on the adjustment of the light beam propagation direction by the first reflector 6 and the second reflector 7, the arrangement of the laser is facilitated and the length of the laser is reduced, and the first reflector 6 and the second reflector 7 are further arranged to be movable, such as sliding the first reflector 6 and the second reflector 7 on the mounting seat, thereby realizing the distance adjustment between the power amplifier system 2 and the laser frequency conversion system 4; and the adjustment distance of the first reflector 6 and the second reflector 7 is L, and the distance of the optical path extension is 2L.

[0034] In some preferred embodiments, the distance between the laser frequency conversion system 4 and the shaper 5 is adjustable; based on the adjustable distance between the two, that is, the adjustable optical path length, the size of the light spot formed at the shaper 5 can be adjusted to avoid the light spot being too large or too small, thereby increasing the adjustment range of the light spot; in particular, it can avoid the divergence angle in the light beam system being too large, so as to facilitate the shaping and collimation processing of the shaper 5.

[0035] As an implementation method, an optical path folding system may be provided between the laser frequency conversion system 4 and the shaper 5 , such as providing a plurality of reflectors or other folding systems capable of extending the optical path.

[0036] As a second implementation, the laser frequency conversion system 4 and / or the shaper 5 may also be arranged to be slidably connected to a mounting seat (not shown) to change the distance between the laser frequency conversion system 4 and the shaper 5; As a third implementation method, the shell for installing the laser frequency conversion system 4 and the shaper 5 can also be configured to be retractable, and the laser frequency conversion system 4 and the shaper 5 are respectively arranged on two parts that can be relatively retracted to change the distance between them when the shell is pulled.

[0037] Preferably, a third reflector 8 and a fourth reflector 9 are also included; the third reflector 8 is used to reflect the light beam output by the laser frequency conversion system 4 into the fourth reflector 9; the fourth reflector 9 is used to reflect the light beam output by the third reflector 8 into the shaper 5, preferably, the reflected light of the fourth reflector 9 is parallel to the incident light of the third reflector 8; the fourth reflector 9 and the third reflector 8 are configured to be able to move along the propagation direction of the incident light of the third reflector 8; based on the adjustment of the light beam propagation direction by the third reflector 8 and the fourth reflector 9, the arrangement of the laser is facilitated and the length of the laser is reduced, and the third reflector 8 and the fourth reflector 9 are further arranged to be movable, such as sliding the third reflector 8 and the fourth reflector 9 on the mounting seat, thereby realizing the distance adjustment between the laser frequency conversion system 4 and the shaper 5; and the adjustment distance of the third reflector 8 and the fourth reflector 9 is L, and the distance of the optical path extension is 2L.

[0038] In some preferred embodiments, a window mirror 10 is further included; the window mirror 10 is arranged on the light output side of the shaper 5 .

[0039] In some preferred embodiments, the shaper 5 can be a beam expander pair or a prism pair, which can be rotated to control the spot shape by optimizing the beam expansion spacing.

[0040] The following is an explanation of the method of using the laser of the present invention in combination with actual cases: The seed source 1 is selected as a laser with an output power of 80mw and a pulse width of about 15ps, which is amplified into a 100w laser by the amplification system 2. The beam quality factor M 2 Less than 1.5, the spot roundness is greater than 90%; the spot size at the laser frequency conversion system 4 is adjusted through the beam expansion system 3 (such as adjusted to 1mm or 2mm, etc., determined according to specific needs), by controlling the divergence angle of the beam expansion system 3 and setting frequency doubling crystals 41 of different lengths, the frequency doubling light output by the frequency doubling crystal 41 meets the required process requirements (mainly controlling the frequency doubling efficiency), and then the length of the sum frequency crystal 42 is matched to achieve the best ultraviolet light output (output power and spot quality), and then the distance between the laser frequency conversion system 4 and the third reflector 8 is extended, so that the spot size on the third reflector 8 is 3mm, and finally the spot size and astigmatism parameters of the light outlet are controlled by the shaper 5. After the parameters are adjusted, the window mirror 10 is sealed.

[0041] Before the laser of the present invention is used, the diameter of the ultraviolet beam is generally about 1 mm. After adopting this solution, the diameter of the ultraviolet beam can be expanded to about 3 mm. It is calculated that the peak power density will drop by 9 times, which is nearly an order of magnitude change. It can very effectively extend the optical life of the ultraviolet back-end device; and it can achieve the output of 15W, 20W and 50W of ultraviolet light.

[0042] The embodiments of the present invention are described above in conjunction with the accompanying drawings, but the present invention is not limited to the above-mentioned specific implementation modes, which are merely illustrative rather than restrictive. Under the guidance of the present invention, ordinary technicians in this field can also make many forms without departing from the scope of protection of the present invention and the claims, all of which are within the protection of the present invention.

Claims

1. A large spot ultraviolet high power picosecond laser, characterized in that: It includes seed source, power amplification system, beam expansion system, laser frequency conversion system and shaper; The seed source is used to generate an infrared light beam; The power amplification system, the beam expansion system, the laser frequency conversion system and the shaper are arranged in sequence along the propagation direction of the infrared light beam; The power amplification system is used to amplify the power of the infrared light beam emitted by the seed source; The beam expansion system is used to adjust the divergence angle of the infrared light beam to increase the size of the light spot formed at the laser frequency conversion system; The laser frequency conversion system is used to convert the infrared light beam into an ultraviolet light beam; The shaper is used to shape the ultraviolet light beam and then output it externally.

2. The large-spot ultraviolet high-power picosecond laser according to claim 1, characterized in that: The beam expansion system is an infrared beam expansion system, and comprises a positive lens, a negative lens and a base; The negative lens and the positive lens are arranged in sequence along the propagation direction of the light beam, and can be installed on the base to be close to or far away from each other along the propagation direction of the light beam.

3. The large-spot ultraviolet high-power picosecond laser according to claim 1, characterized in that: The laser frequency conversion system includes a frequency doubling crystal and a sum frequency crystal; The frequency doubling crystal and the sum frequency crystal are arranged in sequence along the propagation direction of the light beam; The frequency doubling crystal is used to convert part of the input infrared light into green light; The sum frequency crystal is used to convert the output light of the frequency doubling crystal into ultraviolet light.

4. The large-spot ultraviolet high-power picosecond laser according to claim 1, characterized in that: The power amplification system comprises an amplifier and an acousto-optic modulator arranged in sequence along the propagation direction of the light beam; The amplifier is used to amplify the power of the infrared light beam emitted by the seed source; The acousto-optic modulator is used to control the power of the light beam output by the amplification system.

5. The large-spot ultraviolet high-power picosecond laser according to claim 4, characterized in that: Also included is a beam adjustment system; The beam adjustment system is used to adjust the beam diameter of the infrared beam at the AOM to be smaller than the effective aperture of the AOM.

6. The large-spot ultraviolet high-power picosecond laser according to claim 1, characterized in that: The distance between the power amplification system and the laser frequency conversion system is adjustable.

7. The large-spot ultraviolet high-power picosecond laser according to claim 6, characterized in that: Also includes a first reflector and a second reflector; The first reflector is used to reflect the light beam output by the power amplification system into the beam expansion system; The second reflector is used to reflect the light beam output by the beam expansion system into the laser frequency conversion system; The second reflector and the first reflector are configured to be movable along a propagation direction of incident light on the first reflector.

8. The large-spot ultraviolet high-power picosecond laser according to claim 1, characterized in that: The distance between the laser frequency conversion system and the shaper is adjustable.

9. The large-spot ultraviolet high-power picosecond laser according to claim 8, characterized in that: Also included is a third reflector and a fourth reflector; The third reflector is used to reflect the light beam output by the laser frequency conversion system into the fourth reflector; The fourth reflector is used to reflect the light beam output by the third reflector into the shaper; The fourth reflector and the third reflector are configured to be movable along a propagation direction of incident light of the third reflector.

10. The large-spot ultraviolet high-power picosecond laser according to claim 1, characterized in that: It also includes a window mirror; the window mirror is arranged on the light output side of the shaper.

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