High-beam-quality 193nm ultraviolet laser generating device

Abstract

The invention discloses a high-beam-quality 193nm ultraviolet laser generating device, and relates to the technical field of laser electronics. The device comprises a 1064nm picosecond pumping laser source and a 2053nm picosecond laser source which are used for generating pumping laser; the frequency doubling crystal, the frequency quadruplicating crystal, the 213nm sum frequency crystal and the 193nm sum frequency crystal are used for nonlinear frequency conversion; the temperature control device is used for controlling the temperature of the crystal; the dichroic mirror is used for separating the laser; the cylindrical mirror is used for beam shaping; and a lens for focusing the light beam. According to the device, a 1064nm light source is used for performing quadruplicated frequency to obtain 213nm laser, and the obtained 213nm laser and 2053nm laser are input into a nonlinear frequency conversion module to obtain 193nm laser. The device ensures high power of laser output, has good stability and excellent light beam quality, is simple in structure, and is suitable for the fields of photoetching, spectroscopy, medicine and the like.

Description

Technical Field

[0001] The present invention relates to the field of laser electronics technology, and in particular, to a 193 nm ultraviolet laser generating device with high beam quality. Background Art

[0002] 193 nm ultraviolet lasers have extensive applications in the fields of lithography, spectroscopy, medicine, etc. For example, 193 nm lasers as ArF oscillators and amplifiers have been successfully used in lithography. However, the low coherence of ArF excimer lasers limits their wider applications. Compared with excimer lasers, 193 nm deep ultraviolet light sources obtained based on nonlinear frequency conversion of solid-state lasers have the advantages of high beam quality, high repetition rate, high coherence, etc., longer lifespan, and lower maintenance costs. They have been used in semiconductor detection, fiber grating inscription, etc., and have great market prospects and development potential.

[0003] Currently, the generation of 193 nm lasers relies on the cascaded sum-frequency process of nonlinear optical crystals (such as LBO, KBBF). The growth technology of deep ultraviolet crystals is complex. For example, the layered structure of KBBF crystals makes it difficult to process them into practical devices, and it is necessary to rely on prism coupling technology to achieve deep ultraviolet output, which increases the technical complexity and cost. The conversion efficiency of LBO crystals is relatively low, and the low efficiency limits the improvement of output power. The walk-off angle of BBO crystals is relatively large, making it difficult to ensure beam quality and efficiency. At the same time, the crystal is easily affected by thermal effects and optical damage at high power, and it is difficult to meet the industrial requirements for 193 nm lasers with high beam quality and high efficiency. In addition, in the design of optical systems, existing lasers often do not configure focusing lenses, and the balance relationship between the Rayleigh length and the crystal length is not fully considered when applying the relevant theories of crystal optics, resulting in problems such as low conversion efficiency, difficulty in meeting the high-precision processing requirements of beam quality, and difficulty in power improvement during actual experiments and applications. Summary of the Invention

[0004] The technical problem to be solved by the present invention is how to provide a 193 nm ultraviolet laser generating device that can improve beam quality, has high efficiency, and strong stability.

[0005] To solve the above technical problem, the technical solution adopted by the present invention is: A 193 nm ultraviolet laser generating device with high beam quality, characterized by comprising: A first picosecond laser source and a second picosecond laser source. After the laser emitted by the first picosecond laser source passes through a beam splitting prism, one beam of 1064 nm infrared laser pulses enters a second harmonic generation crystal LBO through a first near-infrared reflecting mirror to generate 532 nm green laser pulses. After passing through a first dichroic mirror, the 532 nm green laser pulses are reflected into a fourth harmonic generation laser generating module, and the 1064 nm infrared laser pulses directly pass through the first dichroic mirror; the 532 nm green laser pulses reflected by the first dichroic mirror are focused by a first focusing lens in the fourth harmonic generation module and enter a fourth harmonic generation crystal CLBO. The fourth harmonic generation crystal CLBO is fixed in a first temperature control device, and the spot size and beam quality of the light beam are controlled by a first cylindrical mirror and a second focusing lens. After being focused by the second focusing lens, 266 nm ultraviolet laser pulses are generated. Both the 532 nm green laser pulses and the 266 nm ultraviolet laser pulses are incident on a second dichroic mirror; Another beam of 1064 nm infrared laser pulses generated after passing through the beam splitting prism enters a first half-wave plate and then enters a first optical delay line. Subsequently, after passing through a second near-infrared reflecting mirror, a third near-infrared reflecting mirror and a third focusing lens, the 1064 nm laser pulses are incident on the second dichroic mirror; The 1064 nm infrared laser pulses and the 266 nm deep ultraviolet laser pulses are combined by the second dichroic mirror and enter a first sum frequency crystal CLBO fixed in a second temperature control device to generate 213 nm ultraviolet laser pulses. The 213 nm ultraviolet laser pulses pass through a second cylindrical mirror and a fourth focusing lens and then enter a third dichroic mirror and enter a second sum frequency module. Among them, the 266 nm ultraviolet laser pulses and the 1064 nm infrared laser pulses pass through the third dichroic mirror and are output; The 2053 nm infrared laser pulses emitted by the second picosecond laser source are controlled in power by a second half-wave plate and a first polarization beam splitter. After passing through a second optical delay line, a fifth focusing lens and a 2053 nm reflecting mirror, they enter the second sum frequency module; The 2053 nm infrared laser pulses and the 213 nm ultraviolet laser pulses are combined by the third dichroic mirror and then enter a second sum frequency crystal CLBO fixed in a third temperature control device to generate 193 nm ultraviolet laser pulses. The 193 nm ultraviolet laser pulses pass through a third cylindrical mirror and then are incident on a fourth dichroic mirror and are separated from the 213 nm ultraviolet laser pulses and the 2053 nm infrared laser pulses and output.

[0006] The beneficial effects of adopting the above technical solution are as follows: The device described in this application uses a 1064nm laser that can output high energy as the fundamental frequency pulse, which can ensure the power density required for nonlinear conversion and obtain a high-power 193nm laser pulse. By taking advantage of the small walk-off of the CLBO crystal, the second harmonic generation device, the first sum frequency device, and the second sum frequency device use CLBO crystals to ensure the beam quality and high conversion efficiency of 193nm, and cylindrical lenses are used to optimize the beam quality of each stage of nonlinear frequency conversion. In addition, the device has an all-solid-state structure, which is more stable and easier to maintain. Brief Description of the Drawings

[0007] The present invention will be further described in detail below with reference to the drawings and specific embodiments.

[0008] Figure 1 is a schematic block diagram of the device according to an embodiment of the present invention; Wherein: 1. First picosecond laser source; 2. Second picosecond laser source; 3. Beam splitting prism; 4. First near-infrared reflector; 5. Second harmonic generation crystal LBO; 6. First dichroic mirror; 7. First focusing lens; 8. Fourth harmonic generation crystal CLBO; 9. First temperature control device; 10. First cylindrical mirror; 11. Second focusing lens; 12. First half-wave plate; 13. First delay line; 14. Second near-infrared reflector; 15. Third near-infrared reflector; 16. Third focusing lens; 17. Second dichroic mirror; 18. Second temperature control device; 19. First sum frequency crystal CLBO; 20. Second cylindrical mirror; 21. Fourth focusing lens; 22. Second half-wave plate; 23. First polarization beam splitter; 24. Second delay line; 25. Fifth focusing lens; 26. 2053nm reflector; 27. Third dichroic mirror; 28. Third temperature control device; 29. Second sum frequency crystal CLBO; 30. Third cylindrical mirror; 31. Fourth dichroic mirror. Detailed Embodiments

[0009] The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

[0010] Many specific details are set forth in the following description in order to provide a thorough understanding of the present invention, but the present invention may be practiced in other ways different from those described herein. Those skilled in the art may make similar extensions without departing from the connotation of the present invention, so the present invention is not limited by the specific embodiments disclosed below.

[0011] As Figure 1As shown in the figure, an embodiment of the present invention discloses a 193nm ultraviolet laser generating device with high beam quality, which includes a first picosecond laser source 1 and a second picosecond laser source 2. In this application, the first picosecond laser source 1 and the second picosecond laser source 2 are respectively a 1064nm picosecond laser source 1 and a 2053nm picosecond laser source 2. Further, the 1064nm picosecond laser source 1 is a pulsed laser oscillator or a pulsed laser amplifier with a neodymium-doped yttrium aluminum garnet (Nd:YAG) crystal or a neodymium-doped yttrium orthovanadate (Nd:YVO4) crystal as the gain medium, with a central wavelength of 1064nm and a repetition frequency of 81.9MHz. The central wavelength of the 2053nm picosecond laser source 2 is 2053nm, and the repetition frequency is 81.9MHz.

[0012] As Figure 1 shown, in the device of the present application, the laser emitted by the first picosecond laser source 1 passes through a beam splitting prism 3 (where the beam splitting prism 3 is used to split the input laser into two beams), and one of the 1064nm infrared laser pulses is incident on a second harmonic generation crystal LBO 5 through a first near-infrared mirror 4 to generate a 532nm green laser pulse; among them, the first near-infrared mirror 4 is coated with a 1064nm high-reflection film, and the second harmonic generation crystal LBO 5 is an LBO crystal that can perform second harmonic conversion on 1064nm laser, and both light-passing surfaces of the crystal are coated with 1064nm and 532nm anti-reflection films; after passing through a first dichroic mirror 6, the 532nm green laser pulse is reflected into a fourth harmonic generation laser generation module, while the 1064nm infrared laser pulse directly passes through the first dichroic mirror 6 (the coating characteristics of the first dichroic mirror 6 are high reflection for 532nm laser and high transmission for 1064nm).

[0013] As Figure 1As shown, the 532 nm green laser pulse reflected by the first dichroic mirror 6 is focused by the first focusing lens 7 and injected into the frequency quadrupling crystal CLBO 8 in the frequency quadrupling module. Among them, the first focusing lens 7 is coated with an antireflection film for 532 nm and an antireflection film for 266 nm. The frequency quadrupling crystal CLBO 8 is fixed in the first temperature control device 9, and the spot size and beam quality of the light beam are controlled by the first cylindrical lens 10 and the second focusing lens 11. Among them, the first temperature control device 9 can control the temperature to be maintained at 145 °C and achieve temperature adjustment of ±0.1 °C. The frequency quadrupling crystal CLBO 8 is a crystal CLBO that can double the frequency of the 532 nm laser. The low walk-off angle of the CLBO crystal reduces beam distortion, and at the same time, the high damage threshold supports high-power output. Both light-passing surfaces of the crystal are coated with antireflection films for 532 nm and 266 nm. The second focusing lens 11 is coated with an antireflection film for 532 nm and an antireflection film for 266 nm. The first cylindrical lens 10 is coated with antireflection films for 1064 nm, 532 nm, 266 nm, and 213 nm, and is used to improve the beam quality of the 213 nm ultraviolet laser pulse. After being focused by the second focusing lens 11, a 266 nm ultraviolet laser pulse is generated. The second focusing lens 11 is coated with an antireflection film for 532 nm and an antireflection film for 266 nm. The 532 nm green laser pulse and the 266 nm ultraviolet laser pulse are both incident on the second dichroic mirror 17.

[0014] As Figure 1 shown, another 1064 nm infrared laser pulse generated after passing through the beam splitting prism 3 enters the first half-wave plate 12, then passes through the second near-infrared reflecting mirror 14, the third near-infrared reflecting mirror 15, and the third focusing lens 16, and then the 1064 nm laser pulse is incident on the second dichroic mirror 17. Among them, the first half-wave plate 12 is a half-wave plate for 1064 nm and is coated with an antireflection film for 1064 nm. The first delay device 13 is any device that can delay the 1064 nm laser pulse and is used to make the 1064 nm laser pulse coincide with the 266 nm laser pulse in the time domain. The second near-infrared reflecting mirror 14 and the third near-infrared reflecting mirror 15 are coated with a high-reflection film for 1064 nm. The third focusing lens 16 is coated with an antireflection film for 1064 nm and is used to change the spot size of the light beam incident on the first sum-frequency crystal CLBO 19.

[0015] As Figure 1As shown, the 1064 nm infrared laser pulse and the 266 nm deep ultraviolet laser pulse are combined by the second dichroic mirror 17 and enter the first sum-frequency crystal CLBO 19 fixed in the second temperature control device 18 to generate a 213 nm ultraviolet laser pulse; wherein, the coating characteristics of the second dichroic mirror 17 are highly reflective to 266 nm laser, highly transmissive to 1064 nm and 532 nm, and are used for combining the 266 nm and 1064 nm lasers; the temperature control device 18 can control the temperature to remain at 150 °C and achieve temperature adjustment of ±0.1 °C; the first sum-frequency crystal CLBO 19 is a crystal CLBO capable of sum-frequency, and antireflection films of 1064 nm, 266 nm and 213 nm are coated on both light-transmitting surfaces of the crystal. As Figure 1 shown, the 213 nm ultraviolet laser pulse passes through the second cylindrical mirror 20 and the fourth focusing lens 21 and then enters the second sum-frequency module through the third dichroic mirror 27, wherein the 266 nm ultraviolet laser pulse and the 1064 nm infrared laser pulse pass through the third dichroic mirror 27 and are output; wherein, the fourth focusing lens 21 is coated with antireflection films of 1064 nm, 266 nm and 213 nm and is used to control the spot size of the 213 nm laser incident on the second sum-frequency crystal CLBO 29; the coating characteristics of the third dichroic mirror 27 are highly reflective to 213 nm laser, highly transmissive to 1064 nm, 266 nm and 2053 nm, and are used for combining the 213 nm and 2053 nm lasers. As Figure 1 shown, the 2053 nm infrared laser pulse emitted by the second picosecond laser source 2 passes through the second half-wave plate 22 and the first polarization beam splitter 23 to control the power of the 2053 nm infrared laser pulse, and then enters the second sum-frequency module after passing through the second delay line 24, the fifth focusing lens 25 and the 2053 nm mirror 26; wherein, the second half-wave plate 22 is a 1 / 2 wave plate of 2053 nm and is coated with an antireflection film of 2053 nm; the second delay line 24 is any device capable of delaying the 1064 nm laser pulse and is used to make the 1064 nm laser pulse and the 266 nm laser pulse coincide in time domain; the fifth focusing lens 25 is coated with an antireflection film of 2053 nm and is used to control the spot size of the 2053 nm laser incident on the second sum-frequency crystal 29; the 2053 nm mirror 26 is coated with a high-reflection film of 2053 nm.

[0016] As Figure 1As shown, the 2053nm infrared laser pulse and the 213nm ultraviolet laser pulse are combined by the third dichroic mirror 27 and then enter the second sum-frequency crystal CLBO 29 fixed in the third temperature control device 28 to generate a 193nm ultraviolet laser pulse. Among them, the third temperature control device 28 can control the temperature to be maintained at 150°C and achieve temperature adjustment of ±0.1°C to prevent the CLBO crystal from deliquescing. The second sum-frequency crystal CLBO 29 is a crystal CLBO capable of sum-frequency, and antireflection films of 2053nm, 213nm, and 193nm are coated on both light-transmitting surfaces of the crystal. The 193nm ultraviolet laser pulse passes through the third cylindrical mirror 30 and then is incident on the fourth dichroic mirror 31 and separated from the 213nm ultraviolet laser pulse and the 2053nm infrared laser pulse for output. Among them, the third cylindrical mirror 30 is coated with antireflection films of 193nm, 213nm, and 2053nm to improve the beam quality of the ultraviolet laser pulse. The coating characteristics of the fourth dichroic mirror 31 are high reflectivity for 193nm laser, high transmittance for 193nm and 2053nm, and it is used to separate the 193nm ultraviolet laser.

[0017] In this application, the temperature control device used for the crystal adopts the method of heating with heating sheets. The heating sheets are evenly placed to make the crystal heat evenly, reducing the influence of uneven heat conduction on the spot of the signal light. The temperature control device is placed on a two-dimensional electric displacement stage to adjust the orientation of the beam incident on the crystal to achieve automatic point change, so as to extend the service life of the laser and reduce the maintenance cost. The first sum-frequency device and the second sum-frequency device control the focal spot on the sum-frequency crystal through a separated focusing design, making the Rayleigh distances of the two beams match, reducing the influence of walk-off, and obtaining a higher output power.

[0018] In addition, in this application, the first sum-frequency crystal is a CLBO crystal, the cutting method is vertical cutting, and the size is about 5×5×10mm 3 , θ = 68.3 ∘ , and antireflection films of 1064nm, 266nm, and 213nm are coated on the crystal end face, and the transmittance is greater than 95%. The second sum-frequency crystal is a CLBO crystal, θ = 52 ∘ , and the size is about 5×5×20mm 3 , the cutting method is vertical cutting, and antireflection films of 2053nm, 213nm, and 193nm are coated on the crystal end face, and the transmittance is greater than 95%. The first frequency-doubling crystal is an LBO crystal, θ = 0 ∘ , and the size is about 5×5×20mm 3 , and antireflection films of 1064nm and 532nm are coated, and the transmittance is greater than 95%. The second frequency-doubling crystal is a CLBO crystal, θ = 61.3 ∘ , and the size is about 5×5×10mm 3, coated with antireflection films at 532 nm and 266 nm, with a transmittance greater than 95%. The beam splitting ratio of the beam splitting prism is selectable, and the material of the mirror can be selected as CaF2 to avoid lens damage at high power.

[0019] The device described in this application uses a 1064 nm laser that can output high energy as the fundamental frequency pulse, which can ensure the power density required for nonlinear conversion and obtain a high-power 193 nm laser pulse. Utilizing the advantage of small walk-off of the CLBO crystal, the second harmonic generation device, the first sum frequency generation device, and the second sum frequency generation device use CLBO crystals to ensure the beam quality and high conversion efficiency of 193 nm, and a separated focusing design is adopted to improve the output efficiency. The device has an all-solid-state structure, making the system more stable and easier to maintain.

Claims

1. A high beam quality 193nm ultraviolet laser generating device, characterized in that include: A first picosecond laser source (1) and a second picosecond laser source (2), after the laser emitted by the first picosecond laser source (1) passes through a beam splitter prism (3), a beam of 1064nm infrared laser pulses passes through a first near-infrared reflector (4) and is injected into a frequency doubling crystal LBO (5) to generate a 532nm green laser pulse, which passes through a first dichroic mirror (6), and the 532nm green laser pulse is reflected to a frequency quadrupling laser generating module, and the 1064nm infrared laser pulse directly passes through the first dichroic mirror (6); A 532nm green laser pulse is focused by a first focusing lens (7) in a quadruple frequency module and is injected into a quadruple frequency crystal CLBO (8). The quadruple frequency crystal CLBO (8) is fixed in a first temperature control device (9). The spot size and beam quality of the light beam are controlled by a first cylindrical mirror (10) and a second focusing lens (11). After being focused by the second focusing lens (11), a 266nm ultraviolet laser pulse is generated. Both the 532nm green laser pulse and the 266 ultraviolet laser pulse are injected into a second dichroic mirror (17). Another beam of 1064 nm infrared laser pulses generated after passing through the beam splitter prism (3) enters the first delay device (13) through the first half-wave plate (12), and then passes through the second near-infrared reflector (14), the third near-infrared reflector (15) and the third focusing lens (16) before the 1064 nm laser pulses are incident on the second dichroic mirror (17); The 1064nm infrared laser pulse and the 266nm deep ultraviolet laser pulse are combined through the second dichroic mirror (17) and enter the first sum frequency crystal CLBO (19) fixed in the second temperature control device (18) to generate a 213nm ultraviolet laser pulse. The 213nm ultraviolet laser pulse passes through the second cylindrical mirror (20) and the fourth focusing lens (21) and then passes through the third dichroic mirror (27) to enter the second sum frequency module, wherein the 266nm ultraviolet laser pulse and the 1064nm infrared laser pulse are output through the third dichroic mirror (27); The 2053nm infrared laser pulse emitted by the second picosecond laser source (2) passes through a second half-wave plate (22) and a first polarization beam splitter (23) to control the power of the 2053nm infrared laser pulse, and enters a second sum frequency module after passing through a second delay device (24), a fifth focusing lens (25) and a 2053nm reflector (26); The 2053nm infrared laser pulse and the 213nm ultraviolet laser pulse are combined by a third dichroic mirror (27) and then injected into a second sum frequency crystal CLBO (29) fixed in a third temperature control device (28) to generate a 193nm ultraviolet laser pulse. The 193nm ultraviolet laser pulse passes through a third cylindrical mirror (30) and then injected into a fourth dichroic mirror (31) to be separated from the 213nm ultraviolet laser pulse and the 2053nm infrared laser pulse and then output.

2. The high beam quality 193nm ultraviolet laser generating device according to claim 1, characterized in that: The first picosecond laser source (1) and the second picosecond laser source (2) are respectively a 1064 nm picosecond laser source (1) and a 2053 nm picosecond laser source (2).

3. The high beam quality 193nm ultraviolet laser generating device as claimed in claim 2, characterized in that: The 1064nm picosecond laser source (1) is a pulse laser oscillator or a pulse laser amplifier using a neodymium-doped yttrium aluminum garnet (Nd:YAG) crystal or a neodymium-doped yttrium vanadate (Nd:YVO4) crystal as a gain medium, and has a repetition frequency of 81.9MHz.

4. The high beam quality 193nm ultraviolet laser generating device as claimed in claim 2, characterized in that: The central wavelength of the 2053 nm picosecond laser source (2) is 2053 nm, and the repetition frequency is 81.9 MHz.

5. The high beam quality 193 nm ultraviolet laser generating device according to claim 1, characterized in that: The first delay device (13) and the second delay device (24) are any device capable of delaying a 1064nm infrared laser pulse, and are used to make the time domain of the 1064nm infrared laser pulse coincide with the time domain of the 266nm deep ultraviolet laser pulse.

6. The high beam quality 193 nm ultraviolet laser generating device according to claim 1, characterized in that: The first half-wave plate (12) is a half-wave plate for 1064nm infrared laser pulses and is coated with a 1064nm anti-reflection film; the second half-wave plate (23) is a half-wave plate for 2053nm infrared laser pulses and is coated with a 2053nm anti-reflection film; the first near-infrared reflector (4), the second near-infrared reflector (14) and the third near-infrared reflector (15) are coated with a 1064nm infrared laser pulse high-reflection film; and the 2053nm reflector (26) is coated with a 2053nm infrared laser pulse high-reflection film.

7. The high beam quality 193nm ultraviolet laser generating device according to claim 1, characterized in that: The double frequency crystal LBO (5) is an LBO crystal capable of double frequency conversion of a 1064nm infrared laser pulse, and the two light-transmitting surfaces of the crystal are coated with 1064nm and 532nm anti-reflection films; the quadruple frequency crystal CLBO (8) is a crystal CLBO capable of double frequency conversion of a 532nm laser, and the two light-transmitting surfaces of the crystal are coated with 532nm and 266nm anti-reflection films; the first sum frequency crystal CLBO (19) is a crystal CLBO capable of sum frequency conversion, and the two light-transmitting surfaces of the crystal are coated with 1064nm, 266nm and 213nm anti-reflection films; the second sum frequency crystal CLBO (29) is a crystal CLBO capable of sum frequency conversion, and the two light-transmitting surfaces of the crystal are coated with 2053nm, 213nm and 193nm anti-reflection films.

8. The high beam quality 193nm ultraviolet laser generating device according to claim 1, characterized in that: The first temperature control device (9) controls the temperature to be maintained at 145°C and can adjust the temperature by ±0.1°C; the second temperature control device (18) controls the temperature to be maintained at 150°C and can adjust the temperature by ±0.1°C; the third temperature control device (28) controls the temperature to be maintained at 150°C and can adjust the temperature by ±0.1°C.

9. The high beam quality 193nm ultraviolet laser generating device according to claim 1, characterized in that: The coating characteristics of the first dichroic mirror (6) are high reflection for 532nm laser and high transmittance for 1064nm laser; the coating characteristics of the second dichroic mirror (17) are high reflection for 266nm laser and high transmittance for 1064nm laser and 532nm laser, and are used for beam combining of 266nm and 1064nm lasers; the coating characteristics of the third dichroic mirror (27) are high reflection for 213nm laser and high transmittance for 1064nm laser, 266nm laser and 2053nm laser, and are used for beam combining of 213nm laser and 2053nm laser; the coating characteristics of the fourth dichroic mirror (31) are high reflection for 193nm laser and high transmittance for 193nm laser and 2053nm laser, and are used for separating 193nm ultraviolet laser.

10. The high beam quality 193nm ultraviolet laser generating device according to claim 1, characterized in that: The first focusing lens (7) and the second focusing lens (11) are coated with 532nm and 266nm anti-reflection films; the third focusing lens (16) is coated with a 1064nm anti-reflection film, which is used to change the size of the light spot incident on the first sum frequency crystal CLBO (19); the fourth focusing lens (21) is coated with 1064nm, 266nm and 213nm anti-reflection films, which is used to control the size of the light spot of the 213nm laser incident on the second sum frequency crystal (11); the fifth focusing lens (25) is coated with a 1064nm, 266nm and 213nm anti-reflection films, which is used to control the size of the light spot of the 213nm laser incident on the second sum frequency crystal (11); The first cylindrical mirror (10) and the second cylindrical mirror (20) are coated with 1064nm, 532nm, 266nm and 213nm anti-reflection films, which are used to improve the beam quality of the 213nm ultraviolet laser pulse; and the third cylindrical mirror (30) is coated with 193nm, 213nm and 2053nm anti-reflection films, which are used to improve the beam quality of the ultraviolet laser pulse.

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