A nanosecond pulse train laser

Abstract

The utility model provides a kind of nanosecond pulse train laser, including the pump source, pump coupling component and the resonant cavity being constituted by 0 ° reflector and cavity mirror as two end surfaces that are sequentially arranged along optical path, the resonant cavity is sequentially included laser crystal, first acoustooptic modulator and second acoustooptic modulator from 0 ° reflector side. The utility model is provided with first acoustooptic modulator and second acoustooptic modulator in resonant cavity, first acoustooptic modulator is modulated to generate periodic pulse fundamental light, then second acoustooptic modulator is modulated, and periodic pulse train fundamental light is generated in each pulse, nanosecond pulse train laser output is realized, and the quality and precision of laser processing can be greatly improved with simple structure. In addition, frequency-doubling crystal can also be used to frequency-double pulse train fundamental light to form pulse train frequency-doubled light, further improving the application range of the nanosecond pulse train laser.

Description

Technical Field

[0001] This utility model belongs to the field of laser technology, specifically relating to a nanosecond pulse train laser. Background Technology

[0002] Traditional single-pulse laser processing may result in rough edges and an excessively large heat-affected zone, leading to a decline in component performance. However, research shows that laser pulse train mode has higher removal efficiency, better processing quality and precision when applied to laser processing. By adjusting the number of pulses, pulse interval and energy distribution, the amount of material removed and the heat input of the processing area can be precisely controlled, thus effectively solving these technical problems of traditional single-pulse laser processing. However, the nanosecond lasers generated in the existing technology are all single-pulse outputs. Utility Model Content

[0003] The purpose of this invention is to provide a nanosecond pulse train laser, which can at least solve some of the defects existing in the prior art.

[0004] To achieve the above objectives, the present invention adopts the following technical solution:

[0005] A nanosecond pulse train laser includes a pump source, a pump coupling assembly, and a resonant cavity formed by a 0° mirror and a cavity mirror as two end faces arranged sequentially along the optical path. The resonant cavity includes a laser crystal, a first acousto-optic modulator, and a second acousto-optic modulator, starting from the 0° mirror side.

[0006] Furthermore, a frequency doubling crystal is also provided inside the resonant cavity, and the frequency doubling crystal is located between the second acousto-optic modulator and the cavity mirror.

[0007] Furthermore, a dichroic mirror is provided between the frequency doubling crystal and the second acousto-optic modulator. The periodic pulse train fundamental frequency light generated by the second acousto-optic modulator is reflected by the dichroic mirror to the frequency doubling crystal to generate a pulse train frequency-doubled light. The pulse train frequency-doubled light is then transmitted out of the resonant cavity through the dichroic mirror.

[0008] Furthermore, the frequency doubling crystal is an LBO crystal, and its operating temperature is 50°C.

[0009] Furthermore, a polarizer and a 45° reflector are also provided between the second acousto-optic modulator and the cavity mirror.

[0010] Furthermore, the pump source is an optical fiber coupled output semiconductor laser with an output wavelength of 808nm or 878.8nm.

[0011] Furthermore, the pump coupling assembly includes a first pump lens and a second pump lens arranged sequentially along the optical path. Both the first pump lens and the second pump lens are plano-convex lenses coated with double-sided anti-reflective coatings, and the focal length ratio of the first pump lens and the second pump lens is 1:2-1:4.

[0012] Furthermore, the laser crystal is an Nd:YAG crystal or an Nd:YVO4 crystal, with a crystal length of 10-30 mm and a neodymium particle doping concentration of 0.3-0.5% at.

[0013] Compared with the prior art, the beneficial effects of this utility model are as follows:

[0014] The nanosecond pulse train laser provided by this invention achieves nanosecond pulse train laser output by incorporating a first acousto-optic modulator and a second acousto-optic modulator within the resonant cavity. The first acousto-optic modulator first modulates and generates periodic pulsed fundamental frequency light, and then the second acousto-optic modulator modulates it again, generating a periodic pulse train of fundamental frequency light within each pulse. This simple structure significantly improves the quality and precision of laser processing. Furthermore, a frequency-doubling crystal can be used to double the pulse train fundamental frequency light to form a frequency-doubled pulse train, further expanding the application range of this nanosecond pulse train laser.

[0015] The present invention will be further described in detail below with reference to the accompanying drawings. Attached Figure Description

[0016] Figure 1 This is a schematic diagram of the structure of the nanosecond pulse train laser of this utility model.

[0017] Explanation of reference numerals in the attached figures: 1. Pump source; 2. First pump lens; 3. Second pump lens; 4. 0° mirror; 5. Laser crystal; 6. First acousto-optic modulator; 7. Second acousto-optic modulator; 8. Polarizer; 9. 45° mirror; 10. Dichroic mirror; 11. Frequency doubling crystal; 12. Cavity mirror. Detailed Implementation

[0018] The technical solutions of the present utility model will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are only some embodiments of the present utility model, and not all embodiments. Based on the embodiments of the present utility model, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present utility model.

[0019] In the description of this utility model, it should be understood that the terms "center", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this utility model and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this utility model.

[0020] In the description of this utility model, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation", "connection" and "joining" should be interpreted broadly. For example, they can refer to fixed connections, detachable connections, abutting connections, or integral connections. Those skilled in the art can understand the specific meaning of the above terms in this utility model according to the specific circumstances.

[0021] The terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature; in the description of this utility model, unless otherwise stated, "a plurality of" means two or more.

[0022] like Figure 1 As shown, this embodiment provides a nanosecond pulse train laser, including a pump source 1, a pump coupling assembly, and a resonant cavity formed by a 0° reflector 4 and a cavity mirror 12 as two end faces arranged sequentially along the optical path. Starting from the 0° reflector 4 side, the resonant cavity sequentially includes a laser crystal 5, a first acousto-optic modulator 6, and a second acousto-optic modulator 7. In this embodiment, the pump coupling assembly is used to collimate and focus the pump light emitted from the pump source 1 onto the end face of the laser crystal 5, thereby achieving mode matching with the fundamental frequency oscillation light within the resonant cavity; the first acousto-optic modulator 6 is used to generate periodic pulses, and the second acousto-optic modulator 7 is used to generate a periodic pulse train within each pulse.

[0023] Specifically, the pump source 1 is a fiber-coupled semiconductor laser with a beam product of 0.2 × 220 mm·mrad or 0.1 × 220 mm·mrad, an output wavelength of 808 nm / 878.8 nm, and a maximum output pulse power of 150 W. The laser crystal 5 is an Nd:YAG crystal or an Nd:YVO4 crystal with a crystal length of 10-30 mm and a neodymium doping concentration of 0.3-0.5% at.

[0024] In some embodiments, the pump coupling assembly includes a first pump lens 2 and a second pump lens 3 arranged sequentially along the optical path. The first pump lens 2 and the second pump lens 3 are both plano-convex lenses coated with double-sided anti-reflective coatings, and the focal length ratio of the first pump lens 2 and the second pump lens 3 is 1:2-1:4.

[0025] The working principle of the nanosecond pulse train laser in this embodiment is as follows: The pump light emitted from the pump source 1 is collimated and focused into the laser crystal 5 through the first pump lens 2 and the second pump lens 3 for pumping, and laser oscillation is generated in the resonant cavity composed of the 0° reflector 4 and the cavity mirror 12. The oscillating light (i.e., the fundamental frequency oscillation light) is modulated by the first acousto-optic modulator 6 to generate periodic pulse fundamental frequency light. This periodic pulse fundamental frequency light is then modulated by the second acousto-optic modulator 7 to generate periodic pulse train fundamental frequency light in each pulse, thereby realizing the nanosecond pulse train output. By optimizing parameters such as pump light spot, duty cycle, and pump intensity, the number of pulses in the nanosecond pulse train output can be adjusted.

[0026] In an optimized configuration, a polarizer 8 and a 45° reflector 9 are also provided between the second acousto-optic modulator 7 and the cavity mirror 12. The 45° reflector 9 can be used to change the direction of light transmission, thereby shortening the length of the resonant cavity.

[0027] In an optional embodiment, a frequency-doubling crystal 11 can be disposed within the resonant cavity. The frequency-doubling crystal 11 is located between the second acousto-optic modulator 7 and the cavity mirror 12. It doubles the frequency of the generated periodic pulse train fundamental frequency light to form pulse train frequency-doubled light. For example, doubling the frequency of the infrared pulse train fundamental frequency light can generate a green pulse train laser for output, expanding the application range of this nanosecond pulse train laser. The frequency-doubling crystal 11 can be, but is not limited to, an LBO crystal, and the operating temperature of an LBO crystal is 50°C.

[0028] Furthermore, a dichroic mirror 10 is disposed between the frequency doubling crystal 11 and the second acousto-optic modulator 7. The periodic pulse train fundamental frequency light generated by the second acousto-optic modulator 7 is reflected by the dichroic mirror 10 to the frequency doubling crystal 11 to generate a pulse train frequency-doubled light, which is then transmitted out of the resonant cavity through the dichroic mirror 10. In some embodiments, the dichroic mirror 10 can be arranged at a 45° angle, corresponding to the 45° reflector 9. The horizontally incident periodic pulse train fundamental frequency light is reflected by the 45° reflector 9 to the 45° dichroic mirror 10, and after reflection by the 45° dichroic mirror 10, it is horizontally incident into the frequency doubling crystal 11.

[0029] In this embodiment, the 0° reflector 4, the 45° reflector 9, the 45° dichroic mirror 10, and the cavity mirror 12 constitute a resonant cavity to generate fundamental frequency oscillation light. When it is necessary to output fundamental frequency light, the cavity mirror 12 can be set as an output mirror with a certain transmittance for the corresponding wavelength fundamental frequency light. When it is necessary to output frequency-doubled light, the cavity mirror 12 can be set as a dual-wavelength 0° total reflection mirror, so that the frequency-doubled light after being frequency-doubled by the frequency-doubled crystal 11 is totally reflected by the cavity mirror 12 and then led out of the resonant cavity by the dichroic mirror 10.

[0030] The generation process of nanosecond green light pulse trains is illustrated below with a specific embodiment. Pump source 1 has an output wavelength of 808nm, an fiber core diameter of 400µm, a numerical aperture of 0.22, and a maximum output power of 150W. The first pump lens 2 and the second pump lens 3 are plano-convex lenses with double-sided 808nm anti-reflection coatings, with focal lengths of F20mm and F50mm respectively. The first pump lens 2 is positioned 20mm to the right of pump source 1, and the second pump lens 3 is positioned 10mm to the right of the first pump lens 2. The laser crystal 5 is an Nd:YVO4 crystal. Its dimensions are 4×4×30mm, with a neodymium particle doping concentration of 3%at; the frequency doubling crystal 11 is a type of LBO crystal with an operating temperature of 50°C; behind the second pump lens 3, the following components are placed in sequence: a 0° reflector 4, a laser crystal 5, a first acousto-optic modulator 6, a second acousto-optic modulator 7, a polarizer 8, a 45° reflector 9, a 45° dichroic mirror 10, the frequency doubling crystal 11, and a dual-wavelength 0° reflector (i.e., cavity mirror 12), with interphase distances of 20mm, 30mm, 50mm, 50mm, 40mm, 30mm, 20mm, and 10mm, respectively. Its working process is as follows:

[0031] First stage pumping stage: Continuous radio frequency signals are applied to the first acousto-optic modulator 6 and the second acousto-optic modulator 7, and the pump source 1 is turned on to pump the Nd:YVO4 laser crystal 5, completing the storage of fundamental frequency light energy in the Nd:YVO4 laser crystal 5.

[0032] The second stage generates periodic pulsed laser: The first TTL trigger signal (the first TTL trigger signal has a frequency of 1K and a duty cycle of 0.5) is applied separately to the first acousto-optic modulator 6, so that the pump laser generates periodic pulsed fundamental frequency light with a frequency of 1K, a pulse interval of 1000us, a pulse width of 500us, and a single pulse energy of 50mJ.

[0033] The third stage generates pulsed laser beams: while the first TTL trigger signal is applied to the first acousto-optic modulator 6, a second TTL trigger signal is applied to the second acousto-optic modulator 7 within each optical pulse cycle (the second TTL trigger signal has a frequency of 10 Hz and a duty cycle of 0.025), and the pump light is increased to make the laser generate periodic pulsed laser beams with a period of 1K and a pulse width of 10 ns, which are then frequency-doubled by the frequency-doubling crystal 11; wherein, each pulse beam is spaced 500 μs apart, each pulse beam consists of 10 sub-pulses, each sub-pulse is spaced 50 μs apart, the pulse width is 10 ns, and the single pulse energy is 2 mJ, thus generating nanosecond green light pulse beams.

[0034] The above examples are merely illustrative of this utility model and do not constitute a limitation on the scope of protection of this utility model. All designs that are the same as or similar to this utility model are within the scope of protection of this utility model.

Claims

1. A nanosecond pulse train laser, characterized in that: It includes a pump source, a pump coupling assembly, and a resonant cavity formed by a 0° reflector and a cavity mirror as two end faces arranged sequentially along the optical path. Starting from the 0° reflector side, the resonant cavity includes a laser crystal, a first acousto-optic modulator, and a second acousto-optic modulator in sequence.

2. The nanosecond pulse train laser as described in claim 1, characterized in that: The resonant cavity is also equipped with a frequency doubling crystal, which is located between the second acousto-optic modulator and the cavity mirror.

3. The nanosecond pulse train laser as described in claim 2, characterized in that: A dichroic mirror is provided between the frequency doubling crystal and the second acousto-optic modulator. The periodic pulse train fundamental frequency light generated by the second acousto-optic modulator is reflected by the dichroic mirror to the frequency doubling crystal to generate a pulse train frequency-doubled light. The pulse train frequency-doubled light is then transmitted out of the resonant cavity through the dichroic mirror.

4. The nanosecond pulse train laser as described in claim 2, characterized in that: The frequency doubling crystal is an LBO crystal, and its operating temperature is 50°C.

5. The nanosecond pulse train laser as described in any one of claims 1-4, characterized in that: A polarizer and a 45° reflector are also provided between the second acousto-optic modulator and the cavity mirror.

6. The nanosecond pulse train laser as described in claim 1, characterized in that: The pump source is an optical fiber coupled semiconductor laser with an output wavelength of 808nm or 878.8nm.

7. The nanosecond pulse train laser as described in claim 1, characterized in that: The pump coupling assembly includes a first pump lens and a second pump lens arranged sequentially along the optical path. Both the first pump lens and the second pump lens are plano-convex lenses coated with double-sided anti-reflective coatings, and the focal length ratio of the first pump lens and the second pump lens is 1:2-1:

4.

8. The nanosecond pulse train laser as described in claim 1, characterized in that: The laser crystal is an Nd:YAG crystal or an Nd:YVO4 crystal, with a crystal length of 10-30 mm and a neodymium particle doping concentration of 0.3-0.5% at.

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