Large spot ultraviolet high power picosecond laser

Abstract

The application relates to 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 for generating an infrared light beam; the power amplification system, the beam expansion system, the laser frequency conversion system and the shaper are sequentially arranged along the propagation direction of the infrared light beam; the power amplification system is used for power amplifying the infrared light beam emitted by the seed source; the beam expansion system is used for adjusting the divergence angle of the infrared light beam so as to increase the spot size 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 outputting the ultraviolet light beam after shaping. The application realizes ultraviolet large spot, can effectively reduce the peak power density of an ultraviolet device, effectively prolong the service life of the ultraviolet device, can reduce a rear-end ultraviolet beam expansion mirror, thereby reducing the cost of later use and maintenance, and has simple structure and low cost.

Description

TECHNICAL FIELD

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

[0002] The ultraviolet picosecond laser has excellent cold processing effect due to short wavelength and narrow pulse width, and is widely applied to the super-precision processing of consumer electronics, display panels, new energy, PCBs, biological medicine, aerospace and other industries.

[0003] For the ultraviolet high-power picosecond laser, the fatal problem is the service life of the ultraviolet core device, including an ultraviolet crystal, an ultraviolet reflector and a shaping device, and some methods can be used to prolong the service life of the ultraviolet device, such as using a non-coated a-brick crystal, a point replacement design and automatic optimization, but there are still some disadvantages, such as high requirement for electric control design and high cost of regular maintenance of the rear-end device. SUMMARY

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

[0005] The application adopts the following technical scheme:

[0006] The application 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 power amplification system is used for power amplifying the infrared light beam emitted by the seed source. The beam expansion system is used for adjusting the divergence angle of the infrared light beam, so as to increase the spot size 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. The shaper is used for shaping and outputting the ultraviolet light beam.

[0007] In the large-spot ultraviolet high-power picosecond laser, 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 sequentially arranged along the light beam propagation direction and can be installed on the base to approach or move away from each other along the light beam propagation direction.

[0008] In the large-spot ultraviolet high-power picosecond laser of the application, the laser frequency conversion system comprises a frequency doubling crystal and a frequency mixing crystal; the frequency doubling crystal and the frequency mixing crystal are sequentially arranged along the light beam propagation direction; the frequency doubling crystal is used for converting the input infrared light into green light; and the frequency mixing crystal is used for converting the output light of the frequency doubling crystal into ultraviolet light.

[0009] In the large-spot ultraviolet high-power picosecond laser of the application, the power amplification system comprises an amplifier and an acousto-optic modulator sequentially arranged along the light beam propagation direction; the amplifier is used for power amplifying the infrared light beam emitted by the seed source; and the acousto-optic modulator is used for power control of the light beam output by the amplification system.

[0010] In the large-spot ultraviolet high-power picosecond laser of the application, the light beam adjustment system is further comprised; the light beam adjustment system is used for adjusting the light beam diameter of the infrared light beam at the acousto-optic modulator to be less than the effective aperture of the acousto-optic modulator.

[0011] In the large-spot ultraviolet high-power picosecond laser of the application, the distance between the power amplification system and the laser frequency conversion system is adjustable.

[0012] In the large-spot ultraviolet high-power picosecond laser of the application, the first mirror and the second mirror are further comprised; the light beam output by the power amplification system is reflected into the beam expansion system; the second mirror is used for reflecting the light beam output by the beam expansion system into the laser frequency conversion system; and the second mirror and the first mirror are configured to be movable along the light propagation direction of the first mirror.

[0013] In the large-spot ultraviolet high-power picosecond laser of the application, the distance between the laser frequency conversion system and the shaper is adjustable.

[0014] In the large-spot ultraviolet high-power picosecond laser of the application, the third mirror and the fourth mirror are further comprised; the third mirror is used for reflecting the light beam output by the laser frequency conversion system into the fourth mirror; the fourth mirror is used for reflecting the light beam output by the third mirror into the shaper; and the fourth mirror and the third mirror are configured to be movable along the light propagation direction of the third mirror.

[0015] In the large-spot ultraviolet high-power picosecond laser of the application, the window mirror is further comprised; the window mirror is arranged on the light output side of the shaper.

[0016] The technical solution adopted in the application can achieve the following beneficial effects:

[0017] The application mainly provides a large-spot ultraviolet high-power picosecond laser, which is based on a seed source emitting an infrared light beam, power amplification through a power amplification system, adjustment of the divergence angle of the light beam through a beam expansion system to increase the spot diameter formed by the light beam at a laser frequency conversion system, then conversion of the infrared light into ultraviolet light through the laser frequency conversion system, and finally output after shaping by a shaper, realizing ultraviolet large spot, which can effectively reduce the peak power density of the ultraviolet device, effectively prolong the service life of the ultraviolet device, and 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 DRAWINGS

[0018] In order to more clearly illustrate the technical solutions of the embodiments of the application, the drawings needed to be used in the embodiment description will be briefly introduced as follows, which constitutes a part of the application. The schematic embodiments of the application and the description and explanation thereof do not constitute an improper limitation on the application. In the drawings:

[0019] Figure 1 It is a structure schematic view of a large-spot ultraviolet high-power picosecond laser of the application.

[0020] Figure 2 It is a structure schematic view of a beam expansion system of the application.

[0021] Explanation of reference signs:

[0022] 1. Seed source; 2. Power amplification system; 21. Amplifier; 22. Acousto-optic modulator; 23. Light 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 mirror; 7. Second mirror; 8. Third mirror; 9. Fourth mirror; 10. Window mirror. DETAILED DESCRIPTION

[0023] In order to make the purpose, technical solutions and advantages of the application more clear, the technical solutions of the application will be clearly and completely described below by combining the specific embodiments of the application and the corresponding drawings. In the description of the application, it should be noted that the term "or" is generally used in the sense of including "and / or" unless the context clearly indicates otherwise.

[0024] In the description of the present application, it should be noted that unless otherwise explicitly specified and limited, the terms "mounting", "connecting", "connection" should be understood in a broad sense, for example, it can be fixed connection, or detachable connection, or integrally connected, it can be mechanical connection, or magnetic connection, it can be directly connected, or indirectly connected through an intermediate medium, or the internal communication of two elements. For those skilled in the art, the specific meaning of the above terms in the present application can be understood according to the specific circumstances. In addition, in the description of the present application, the terms "first", "second" and the like are only used to distinguish the description, and cannot be understood as indicating or implying relative importance. In the description of the present application, the meaning of "a plurality of" is at least two, for example, two, three or more, etc., unless otherwise explicitly specified and limited.

[0025] Obviously, the described embodiments are only part of the embodiments of the present application, not all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor belong to the scope of protection of the present application.

[0026] To solve the problems in the prior art, the embodiments of the present application provide a large-aperture ultraviolet high-power picosecond laser.

[0027] A large-aperture ultraviolet high-power picosecond laser, as shown in Figure 1 It comprises 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 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 beam; the power amplification system 2 is used to amplify the infrared beam emitted by the seed source 1; the beam expansion system 3 is used to adjust the divergence angle of the infrared 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 beam into an ultraviolet beam; the shaper 5 is used to output after shaping the ultraviolet beam, and the shaper 5 is used to adjust the spot size and the astigmatism parameter.

[0028] The large-aperture ultraviolet high-power picosecond laser of the present application is based on the seed source 1 emitting an infrared beam, the power amplification system 2 amplifying the power, the beam expansion system 3 adjusting the divergence angle of the beam to increase the spot diameter of the beam formed at the laser frequency conversion system 4, then the laser frequency conversion system 4 converts the infrared light into ultraviolet light, and finally the shaper 5 shapes and outputs; it realizes ultraviolet large-aperture, can effectively reduce the peak power density of the ultraviolet device, effectively prolong the service life of the ultraviolet device, and can 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.

[0029] In some preferred embodiments, the beam expander system 3 can be composed of positive and negative lenses; or of one lens and two cylindrical mirrors; or of multiple cylindrical mirrors. There are no specific limitations as long as it can achieve the function of expanding the beam and increasing the divergence angle.

[0030] In some preferred embodiments, the beam expander system 3 is an infrared beam expander system, such as... Figure 2 As shown, the system includes a positive lens 31, a negative lens 32, and a base 33. The negative lens 32 and the positive lens 31 are arranged sequentially along the beam propagation direction and can be mounted close to or far from each other on the base 33 along the beam propagation direction. Taking the movable positive lens 31 as an example, if a groove is provided in the base 33, the positive lens 31 can slide in the groove, which facilitates changing the distance between the positive lens 31 and the negative lens 32 to control the divergence angle. This achieves the purpose of adjusting the beam expansion distance and changing the divergence angle, thus enabling infrared spot control. For example, shortening the beam expansion distance can increase the divergence angle and the infrared spot size, while lengthening the beam expansion distance can decrease the divergence angle and the infrared spot size. Specifically, the focal length of the negative lens 32 can be selected as -20mm, the focal length of the positive lens 31 can be selected as +60mm, and the beam expansion distance is approximately 43mm.

[0031] 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 sequentially along the beam propagation direction; the frequency doubling crystal 41 is used to convert the input infrared light portion 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 cooperation of the frequency doubling crystal 41 and the sum-frequency crystal 42 to achieve the conversion of infrared light into ultraviolet light, the conversion efficiency can be improved; more preferably, it includes multiple frequency doubling crystals 41 and multiple sum-frequency crystals 42 of different lengths, so as to adjust the length of the frequency doubling crystals 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 optimal ultraviolet light output, such as ultraviolet light power and spot quality. Optionally, the length of the frequency doubling crystal 41 can be 10mm, 15mm, 20mm, etc., specifically determined according to the process requirements; the length selection of the sum-frequency crystal 42 is the same as that of the frequency doubling crystal, and will not be described in detail.

[0032] In some preferred embodiments, the power amplification system 2 comprises an amplifier 21 and an acousto-optic modulator 22 arranged in sequence along the propagation direction of the light beam, such as a model AM3; the amplifier 21 is used for power amplification of the infrared light beam emitted by the seed source 1; the acousto-optic modulator 22 is used for power control 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 realized, and different power outputs are realized; preferably, the acousto-optic modulator 22 is used for Bragg diffraction, and the first-order diffraction light is output, thereby realizing different power outputs; wherein the amplifier 21 can be an optical path structure capable of realizing infrared light power amplification, which is not limited here.

[0033] In some preferred embodiments, the light beam adjustment system 23 is further included; the light beam adjustment system 23 is used for adjusting the light beam diameter of the infrared light beam at the acousto-optic modulator 22 to be smaller than the effective aperture of the acousto-optic modulator 22; specifically, the light beam adjustment system 23 can be a beam expander or a beam reducer, which is specifically selected according to the working condition; based on the setting of the light beam adjustment system 23, the light beam diameter entering the acousto-optic modulator 22 is adjusted, which can improve the diffraction efficiency of the acousto-optic modulator 22.

[0034] In some preferred embodiments, the distance between the power amplification system 2 and the laser frequency conversion system 4, or the distance between the beam expander system 3 and the laser frequency conversion system 4 is adjustable; based on the adjustable distance between the two, i.e., the adjustable optical path length, the size of the light spot formed at the laser frequency conversion system 4 can be adjusted, so as to avoid the light spot being too large or too small, thereby improving the range of light spot adjustment; especially, the divergence angle in the light beam system can be avoided from being too large, so as to facilitate the collimation processing of the shaper 5.

[0035] As an implementation manner, an optical path folding system can be arranged between the power amplification system 2 and the laser frequency conversion system 4, or between the beam expander system 3 and the laser frequency conversion system 4, such as a plurality of mirrors or other folding systems capable of realizing optical path extension.

[0036] As a second implementation manner, the power amplification system 2 and / or the laser frequency conversion system 4 can be arranged in sliding connection with a mounting seat (not shown), or the beam expander system 3 and the laser frequency conversion system 4 are arranged in sliding connection with the mounting seat (not shown), so as to change the distance between the power amplification system 2 and the laser frequency conversion system 4, or the distance between the beam expander system 3 and the laser frequency conversion system 4.

[0037] As a third implementation manner, the shell mounting the power amplification system 2 or the beam expander system 3 and the laser frequency conversion system 4 can also be arranged to be drawable, and the power amplification system 2 or the beam expander system 3 and the laser frequency conversion system 4 are arranged on two parts that can be relatively drawn, so as to change the distance between them when the shell is drawn.

[0038] Of course, other distance adjustment between the power amplification system 2 and the laser frequency conversion system 4 can also be selected, which is not limited herein.

[0039] Preferably, the first mirror 6 and the second mirror 7 are further included; the first mirror 6 is used to reflect the light beam output by the power amplification system 2 into the beam expansion system 3; the second mirror 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 mirror 7 is parallel to the incident light of the first mirror 6; the second mirror 7 and the first mirror 6 are configured to be movable along the propagation direction of the incident light of the first mirror 6; based on the adjustment of the propagation direction of the light beam by the first mirror 6 and the second mirror 7, the arrangement of the laser is facilitated, the length of the laser is reduced, and the first mirror 6 and the second mirror 7 are further arranged to be movable, such as slidingly mounted on the mounting seat, so as to realize the distance adjustment between the power amplification system 2 and the laser frequency conversion system 4; and the adjustment distance of the first mirror 6 and the second mirror 7 is L, and the light path is extended by 2L.

[0040] In some preferred embodiments, the laser frequency conversion system 4 and the shaper 5 are configured to be adjustable in distance; based on the adjustable distance between the two, i.e., the adjustable length of the light path, the size of the light spot formed at the shaper 5 can be adjusted, so as to avoid the light spot being too large or too small, and the range of light spot adjustment is improved; especially, the divergence angle in the beam system can be avoided from being too large, so as to facilitate the collimation processing of the shaper 5.

[0041] As an implementation manner, a light path folding system can be arranged between the laser frequency conversion system 4 and the shaper 5, such as a plurality of mirrors or other folding systems capable of extending the light path.

[0042] As a second implementation manner, the laser frequency conversion system 4 and / or the shaper 5 can be slidingly connected with the mounting seat (not shown) to change the distance between the laser frequency conversion system 4 and the shaper 5.

[0043] As a third implementation manner, the shell mounting the laser frequency conversion system 4 and the shaper 5 can be pullable, and the laser frequency conversion system 4 and the shaper 5 are arranged on two parts that can be relatively pulled, so as to change the distance between them when the shell is pulled.

[0044] Preferably, the third mirror 8 and the fourth mirror 9 are further included; the third mirror 8 is used for reflecting the light beam output by the laser frequency conversion system 4 into the fourth mirror 9; the fourth mirror 9 is used for reflecting the light beam output by the third mirror 8 into the shaper 5, preferably, the reflected light of the fourth mirror 9 is parallel to the incident light of the third mirror 8; the fourth mirror 9 and the third mirror 8 are configured to be movable along the propagation direction of the incident light of the third mirror 8; based on the adjustment of the propagation direction of the light beam by the third mirror 8 and the fourth mirror 9, the arrangement of the laser is facilitated, the length of the laser is reduced, and the third mirror 8 and the fourth mirror 9 are further arranged to be movable, such as slidingly mounted on the mounting seat, so that the distance adjustment between the laser frequency conversion system 4 and the shaper 5 is realized; and the adjustment distance of the third mirror 8 and the fourth mirror 9 is L, and the light path is extended by 2L.

[0045] In some preferred embodiments, the window mirror 10 is further included; the window mirror 10 is arranged on the light output side of the shaper 5.

[0046] In some preferred embodiments, the shaper 5 can be a beam expander pair or a prism pair, and the spot shape is controlled by optimizing the beam expander distance and rotation.

[0047] The use method of the laser of the present application is described below in combination with an actual case:

[0048] The seed source 1 is selected to be a laser capable of outputting a power of 80 mw and a pulse width of about 15 ps, and the laser is amplified to 100 w by the amplification system 2, the beam quality factor M 2 is less than 1.5, and the spot roundness is greater than 90%; the spot size at the laser frequency conversion system 4 is adjusted (such as 1 mm or 2 mm, etc., which is determined according to the requirements) by the beam expander system 3, the divergence angle of the beam expander system 3 is controlled, and different lengths of the frequency doubling crystal 41 are set, so that the frequency doubling light output by the frequency doubling crystal 41 meets the process requirements (mainly controlling the frequency doubling efficiency), then the length of the sum frequency crystal 42 is matched to achieve the best ultraviolet light output (output power and spot quality), then the distance between the laser frequency conversion system 4 and the third mirror 8 is extended, so that the spot size on the third mirror 8 is 3 mm, and finally the spot size and the astigmatism parameter of the light output port are controlled by the shaper 5, and after the parameter adjustment is completed, the window mirror 10 is sealed.

[0049] Before the laser of the present application is used, the diameter of the ultraviolet light beam is about 1 mm, and after the scheme is used, the diameter of the ultraviolet light beam can be expanded to about 3 mm, and calculation shows that the peak power density will decrease by 9 times, which is close to a change of one order of magnitude, which can effectively prolong the optical life of the ultraviolet backend device; and 15 W, 20 W and 50 W ultraviolet light can be output.

[0050] The embodiments of the present application are described above with reference to the accompanying drawings, but the present application is not limited to the above-described specific embodiments, and the above-described specific embodiments are merely illustrative, but not restrictive, and a person of ordinary skill in the art can make many forms under the inspiration of the present application without departing from the purpose of the present application and the scope protected by the claims, and all of them belong to the protection of the present application.

Claims

1. A large-spot ultraviolet high-power picosecond laser, characterized in that, This includes a seed source, a power amplification system, a beam expander, a laser frequency conversion system, and a shaper; The seed source is used to generate an infrared beam; The power amplification system, the beam expander, the laser frequency conversion system, and the shaper are arranged sequentially along the propagation direction of the infrared beam; The power amplification system is used to amplify the power of the infrared beam emitted by the seed source; The beam expanding system is used to adjust the divergence angle of the infrared beam to increase the spot size formed at the laser frequency conversion system; The laser frequency conversion system is used to convert the infrared beam into an ultraviolet beam; The shaper is used to shape the ultraviolet beam before outputting it. The beam expanding system is an infrared beam expanding system, and includes a positive lens, a negative lens, and a base; The negative lens and the positive lens are arranged sequentially along the beam propagation direction and can be mounted on the base close to or far from each other along the beam propagation direction. The distance between the laser frequency conversion system and the shaper is adjustable; The laser frequency conversion system includes multiple frequency doubling crystals and multiple sum frequency crystals of different lengths, so as to adjust the length of the frequency doubling crystals and sum frequency crystals in the system according to the spot size.

2. The large-spot ultraviolet high-power picosecond laser according to claim 1, characterized in that, The frequency doubling crystal and the sum frequency crystal are arranged sequentially along the beam propagation direction; The frequency doubling crystal is used to convert the input infrared light portion into green light; The sum-frequency crystal is used to convert the output light of the frequency doubling crystal into ultraviolet light.

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

4. The large-spot ultraviolet high-power picosecond laser according to claim 3, characterized in that, It 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.

5. 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.

6. The large-spot ultraviolet high-power picosecond laser according to claim 5, characterized in that, It 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 expander system; The second reflector is used to reflect the beam output from the beam expander system into the laser frequency conversion system; The second reflector and the first reflector are configured to move along the direction of incident light propagation of the first reflector.

7. The large-spot ultraviolet high-power picosecond laser according to claim 1, characterized in that, It also includes a third and a fourth reflecting mirror; The third reflector is used to reflect the laser 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 and third reflectors are configured to move along the direction of incident light propagation of the third reflector.

8. 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 disposed on the light-emitting side of the shaper.

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