Side pumping seed amplification pulse laser

Abstract

The utility model provides a side pumping seed amplification pulse laser, which comprises a first seed source and a second seed source which are oppositely arranged, and a reflecting mirror capable of rotating by 45 degrees between the two seed sources, the first 45-degree reflecting mirror, the filter, the spatial isolator, the plano-concave lens, the 45-degree horizontal polarizing film, the first traveling wave amplifier, the half-wave plate, the second 45-degree reflecting mirror, the third 45-degree reflecting mirror, the second traveling wave amplifier and the fourth 45-degree reflecting mirror are sequentially arranged on a seed light propagation path. Wherein the reflector capable of rotating by 45 degrees can rotate by 45 degrees clockwise or clockwise and is used for switching different seed light to enter a subsequent light path; the first traveling wave amplifier, the second traveling wave amplifier, the half-wave plate and the plurality of 45-degree reflectors form an annular traveling wave amplifier, and compared with a linear traveling wave amplifier, seed light can be amplified for multiple times. The pulse laser provided by the utility model not only greatly improves the energy storage utilization rate of each amplifier, but also can output large-energy flat-topped light beams with nanosecond-level and subnanosecond-level pulse widths, and can meet the treatment requirements of various hyperpigmentation lesions.

Description

Technical Field

[0001] The utility model relates to the technical field of pulse lasers, in particular to a side-pumped seed amplified pulse laser. Background Art

[0002] Short pulse high energy pulse laser is a laser technology with important applications in the field of medical cosmetology. This laser is currently mainly generated by Q-switching in an optical resonant cavity. Common short pulse high energy pulse lasers include ruby ​​Q-switched lasers, alexandrite Q-switched lasers, NdYAG Q-switched lasers, etc. Among them, NdYAG Q-switched lasers are the most widely used, such as in the treatment of superficial pigmented lesions such as freckles and coffee spots, and superficial vascular proliferative lesions such as port wine stains and spider nevi. It has achieved good results, but it is less effective in the treatment of deep pigmented proliferative lesions. For example, when used to remove various colored tattoos, the Q-switched laser cannot completely destroy the pigment tissue deep in the skin in one irradiation because the pulse width is not short enough. The tattoo at the same location needs to be irradiated multiple times to be completely removed. The Q-switched laser outputs a multi-mode Gaussian beam, and the spot energy distribution is uneven, the center energy is high, and the edge energy is low. When irradiated, hot spots will be generated on the patient's skin, which will increase the risk of burns to the patient's skin. Utility Model Content

[0003] The purpose of the utility model is to provide a side-pumped seed amplified pulse laser, which can output high-energy flat-top beams with nanosecond and sub-nanosecond pulse widths, and can meet the treatment needs of various pigmented hyperplastic lesions. The specific technical solution is as follows:

[0004] A side-pumped seed amplified pulse laser, comprising a first seed source and a second seed source arranged opposite to each other, a rotatable 45° reflector between the first seed source and the second seed source, and a first 45° reflector, a filter, a spatial isolator, a plano-concave lens, and a ring-shaped traveling wave amplifier arranged in sequence in the propagation direction of the seed light;

[0005] The annular traveling wave amplifier comprises a 45° horizontal polarizer after the plano-concave lens, a first traveling wave amplifier after the 45° horizontal polarizer, a half wave plate, a second 45° reflector, a second traveling wave amplifier parallel to the first traveling wave amplifier, and a third 45° reflector and a fourth 45° reflector at both ends of the second traveling wave amplifier;

[0006] The second 45° reflector can vertically reflect the seed light passing through the half wave plate to the third 45° reflector, the third 45° reflector can vertically reflect the seed light to the second traveling wave amplifier, and the fourth 45° reflector can vertically reflect the seed light passing through the second traveling wave amplifier to the 45° horizontal polarizer, thereby forming a ring-shaped light beam loop.

[0007] Furthermore, it also includes a first beam expander in front of the output end of the first seed source and a second beam expander in front of the output end of the second seed source.

[0008] Furthermore, the first traveling wave amplifier includes a first gain medium between the 45° horizontal polarizer and the half wave plate and a first pump source located on the side of the first gain medium, and the second traveling wave amplifier includes a second gain medium between the third 45° reflector and the fourth 45° reflector and a second pump source located on the side of the second gain medium.

[0009] Furthermore, the first gain medium and the second gain medium are both Nd:YAG crystal rods, the diameter of the crystal rods is 7-8 mm, the length is 80-100 mm, the end face angle is 0.3°-0.5°, and the doping concentration is 0.3 at%-0.5 at%.

[0010] Furthermore, the first pump source and the second pump source are both pulse water-cooled xenon lamps, the inner diameter of the pulse water-cooled xenon lamp is 5-7 mm, and the arc length ranges from 80-100 mm.

[0011] Furthermore, the 45° rotatable reflector is mounted on a metal servo whose rotation angle is controlled by PWM via a metal plate, and the metal servo can drive the 45° rotatable reflector to rotate 45° clockwise or counterclockwise around the servo rotation axis.

[0012] Furthermore, both the first beam expander and the second beam expander are Galilean telescopes, and the Galilean telescopes include a concave lens and a convex lens, and the distance between the concave lens and the convex lens is 65 to 75 mm.

[0013] Furthermore, the first seed source is a nanosecond seed source, the second seed source is a sub-nanosecond seed source, and both the nanosecond seed source and the sub-nanosecond seed source are passively Q-switched lasers.

[0014] Furthermore, the central wavelength of the passive Q-switched laser output is 1064nm, the diameter of the light spot at the light outlet is 0.9-1.0mm, and the beam quality is less than 1.3mm.

[0015] Furthermore, the filter includes a first polarizer, a second polarizer and a spatially variable wave plate, wherein the first polarizer and the second polarizer are located on both sides of the spatially variable wave plate, and the spatially variable wave plate is a half-wave plate whose optical axis rotates radially.

[0016] The utility model provides a side-pumped seed amplified pulse laser, which has the following beneficial effects:

[0017] The utility model provides a side-pumped seed amplified pulse laser, which is a ring-shaped traveling wave amplifier composed of two traveling wave amplifiers. Compared with a linear traveling wave amplifier, the seed light can be amplified multiple times, thereby improving the energy storage utilization rate of each amplifier. At the same time, the laser can output high-energy flat-top beams with nanosecond and sub-nanosecond pulse widths, which can meet the treatment needs of various pigmented hyperplastic lesions. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 It is a schematic diagram of a side-pumped seed amplified pulse laser provided by the utility model.

[0019] Explanation of the reference numerals: 1-nanosecond seed; 5-subnanosecond seed; 2, 4-beam expander; 3-rotatable 45° reflector; 6, 18, 19, 23-45° reflector; 7, 9-polarizer; 8-spatially variable wave plate; 10-filter; 11-spatial isolator; 12-plano-concave lens; 13-45° horizontal polarizer; 16-first traveling wave amplifier; 17-half wave plate; 14, 21-pulsed water-cooled xenon lamp; 15, 20-Nd:YAG crystal rod; 22-second traveling wave amplifier. DETAILED DESCRIPTION

[0020] The following will be combined with the accompanying drawings provided by the utility model to clearly and completely describe the technical solutions in the embodiments of the utility model. According to the following description, the advantages and features of the utility model will be clearer. It should be noted that the drawings are all in a very simplified form and are not in precise proportions, which are only used to conveniently and clearly assist in explaining the purpose of the embodiments of the utility model.

[0021] In the description of the present invention, terms such as "upper", "lower", "left", "right", "front", "back", "center", "horizontal", "vertical", "top", "bottom", "inside" and "outside" and other orientations or positional relationships are based on the orientations or positional relationships shown in the accompanying drawings and are only for the convenience of description and simplification of operation, and do not indicate or imply that the referred device or element must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present invention.

[0022] Example:

[0023] This embodiment provides a side-pumped seed amplified pulse laser, see Figure 1As shown, the laser includes a first seed source 1 and a second seed source 5 arranged opposite to each other, a first beam expander 2 in front of the output end of the first seed source 1 and a second beam expander 4 in front of the output end of the second seed source 5, and a rotatable 45° reflector 3 between the two beam expanders, and also includes a first 45° reflector 6, a filter 10, a spatial isolator 11, a plano-concave lens 12, a 45° horizontal polarizer 13, a first traveling wave amplifier 16, a half wave plate 17, a second 45° reflector 18, a third 45° reflector 19, a second traveling wave amplifier 22 and a fourth 45° reflector 23 arranged in sequence in the propagation direction of the seed light. Among them, the rotatable 45° reflector 3 can be rotated 45° clockwise or clockwise to switch different seed lights into the subsequent optical path; the 45° horizontal polarizer 13, the first traveling wave amplifier 16, the half wave plate 17, the second 45° reflector 18, the third 45° reflector 19, the second traveling wave amplifier 22 and the fourth 45° reflector 23 form a ring traveling wave amplifier. Compared with the linear traveling wave amplifier, the seed light can be amplified multiple times, which greatly improves the energy storage utilization rate of each amplifier, and the laser can output high-energy flat-top beams with nanosecond and sub-nanosecond pulse widths, which can meet the treatment needs of various pigmented hyperplastic lesions.

[0024] The pulse laser is described in detail below.

[0025] As a specific embodiment of the first seed source 1 and the second seed source 5, the first seed source 1 and the second seed source 5 are arranged opposite to each other, and the first and second beam expanders 2 and 4 are respectively provided in front of the output ends of the first and second seed sources 1 and 5, and the rotatable 45° reflector 3 is located between the first and second beam expanders 2 and 4. The rotatable 45° reflector 3 is installed on a metal servo whose rotation angle is controlled by PWM through a metal disk, and the rotatable 45° reflector 3 can rotate around the servo rotation axis, and the rotation angle is -45° to 45°, and the 45° reflector 3 can be driven to rotate by rotating the servo rotation axis to switch different seed sources. A first 45° reflector 6 is provided on the optical path of the reflected light beam of the rotatable 45° reflector 3 to reflect the seed light into the subsequent optical path.

[0026] Optionally, the first seed source 1 is a nanosecond seed source, and the second seed source 5 is a sub-nanosecond seed source. Both the nanosecond seed source and the sub-nanosecond seed source are passively Q-switched microchip lasers. The central wavelength output by the passively Q-switched microchip laser is 1064nm, the light outlet spot diameter is 0.9-1.0mm, and the beam quality is <1.3mm; the laser pulse width of the nanosecond seed source is 1-2ns, and the laser pulse width of the sub-nanosecond seed source is 300-400ps.

[0027] Optionally, the beam expander 2 and the beam expander 4 are Galilean telescopes, each including an output concave lens and an output convex lens, and the distance between the two lenses is 65 to 75 mm.

[0028] As a specific implementation of the filter 10, the filter 10 is behind the first 45° reflector 6. The filter 10 includes a first polarizer 7, a second polarizer 9, and a spatially variable wave plate 8. The first polarizer 7 and the second polarizer 9 are located on both sides of the spatially variable wave plate 8. The spatially variable wave plate 8 is a half wave plate whose optical axis rotates radially. The filter 10 is a spatially variable transmission filter that can convert a Gaussian beam into a flat-top beam.

[0029] As a specific implementation of the spatial isolator 11, the spatial isolator 11 is after the filter 10. The spatial isolator 11 only allows polarized light to be input from its forward direction and blocks the input in the opposite direction. Forward horizontal polarized light is input and horizontal polarized light is output, and reverse horizontal polarized light is input and horizontal polarized light is converted into vertical polarized light and not output.

[0030] As a specific implementation of the plano-concave lens 12, the plano-concave lens 12 is behind the space isolator, the plano-concave lens 12 is placed vertically, and its focal length can be 1 m.

[0031] As a specific embodiment of the ring traveling wave amplifier, the 45° horizontal polarizer 13 is behind the plano-concave lens, the first traveling wave amplifier 16 includes a first gain medium 15 after the horizontal polarizer 13 and a first pump source 14 located on the side of the first gain medium 15, and the first gain medium 15 is followed by a half wave plate 17 and a second 45° reflector 18 in sequence, and the inclination direction of the second 45° reflector 18 is opposite to that of the 45° horizontal polarizer 13; the second traveling wave amplifier 22 includes a second gain medium 20 parallel to the first gain medium 14 and a second pump source 21 located on the side of the second gain medium 20, and a third 45° reflector 19 and a fourth 45° reflector 23 are respectively arranged at both ends of the second gain medium 20. The second 45° reflector 18 and the third 45° reflector 19 are located at the same end of the two gain media, and the distance from the second 45° reflector 18 to the first gain medium 14 is equal to the distance from the third 45° reflector 19 to the second gain medium 20, and the inclination directions of the two reflectors are opposite, so the second 45° reflector 18 can reflect the seed light passing through the first gain medium 14 to the surface of the third 45° reflector 19, and the third 45° reflector 19 can reflect the seed light into the second gain medium 20. The fourth 45° reflector 23 and the 45° horizontal polarizer 13 are located at the other end of the two gain media, and the distance from the fourth 45° reflector 23 to the second gain medium 20 is equal to the distance from the 45° horizontal polarizer 13 to the first gain medium 14, and the inclination directions of the fourth 45° reflector 23 and the third 45° reflector 19 are opposite, so the fourth 45° reflector 23 can reflect the seed light passing through the second gain medium 20 to the 45° horizontal polarizer 13. The above-mentioned ring traveling wave amplifier can make the seed light pass through the gain medium multiple times to be amplified.

[0032] Optionally, the first gain medium 14 and the second gain medium 20 are both Nd:YAG crystal rods, the diameter of the crystal rods is 7-8 mm, the length is 80-100 mm, the end face angle is 0.3°-0.5°, and the doping concentration is 0.3at%-0.5at%.

[0033] Optionally, the first pump source 15 and the second pump source 21 are both pulse water-cooled xenon lamps, the inner diameter of the pulse water-cooled xenon lamp is 5-7 mm, and the arc length ranges from 80-100 mm.

[0034] The working process and principle of a side-pumped seed amplified pulse laser of this embodiment are described in detail below in conjunction with specific data values.

[0035] Among them, the nanosecond seed light and sub-nanosecond seed light are horizontally polarized 1064nm Gaussian laser beams, with an output frequency of 1-10Hz and a maximum single pulse energy of 300uJ; the nanosecond seed light has an exit spot diameter of 0.9mm, a pulse width of 1.5ns, and a beam quality of 1.25; the sub-nanosecond seed light has an exit spot diameter of 1mm, a pulse width of 350ps, and a beam quality of 1.2. Beam expanders 2 and 4 both have 6-fold beam expansion. The inner diameter of the pulsed water-cooled xenon lamp in the first traveling wave amplifier 16 and the second traveling wave amplifier 22 is 5mm, the arc length is 80mm, and it is ignited by a pulse voltage source. The maximum output power of the pulse power supply is 10Hz and 400W. The diameter of the Nd:YAG crystal rod is 8 mm, the length is 80 mm, and the doping concentration is 0.5 at.%. The end face cutting angle of the Nd:YAG crystal rod in the first traveling wave amplifier 16 is 0.3°, and the end face cutting angle of the Nd:YAG crystal rod in the second traveling wave amplifier 22 is 0.5°. The first traveling wave amplifier 16 and the first traveling wave amplifier 22 respectively use Nd:YAG crystal rods with different end face cutting angles to avoid the generation of self-laser.

[0036] After the nanosecond seed light or sub-nanosecond seed light is expanded by the beam expander 2 or the beam expander 4, the spot becomes larger and has a diameter of about 6 mm. The rotatable 45° reflector 3 is driven by the metal servo to rotate 45° clockwise or counterclockwise around the servo rotation axis. When the lens is rotated 45° clockwise or counterclockwise, the nanosecond seed light or sub-nanosecond seed light is reflected by the rotatable 45° reflector 3, and then reflected by the first 45° reflector 6, and then passes through the filter 10, the spatial isolator 11, and the plano-concave lens 12 in sequence. The seed light begins to enter the ring traveling wave amplifier, and is first converted into a horizontally polarized flat-top laser beam with a divergence angle of about 5 mrad by a 45° horizontal polarizer 13, amplified for the first time by the first traveling wave amplifier 16, and the polarization state is rotated 90° to become vertical polarization by the half wave plate 17, and is reflected by the second 45° reflector 18 and the third 45° reflector 19, amplified for the second time by the second traveling wave amplifier 22, and reflected back to the 45° horizontal polarizer by the fourth 45° reflector 23; the vertically polarized flat-top laser beam at this time The light beam is reflected by the 45° horizontal polarizer 13, and is amplified for the third time by the first traveling wave amplifier 16. The polarization state is rotated 90° to become horizontal polarization by the half wave plate 17, and is reflected by the second 45° reflector 18 and the third 45° reflector 19. It is amplified for the fourth time by the second traveling wave amplifier 22. After being reflected by the fourth 45° reflector 23, the horizontally polarized flat-top laser beam finally passes through the 45° horizontal polarizer 13, and outputs a 500mJ pulse laser with a pulse width of 1.5ns or 350ps. In the above process, the output energy after the first stage amplification is about 5mJ, the output energy after the second stage amplification is about 40mJ, and the output energy after the third stage amplification is about 150mJ, and the maximum laser output frequency is 10Hz.

[0037] The utility model proposes a side-pumped seed amplified pulse laser, which is a ring-shaped traveling wave amplifier system composed of two traveling wave amplifiers. Compared with a linear traveling wave amplifier system in which the seed can only be amplified once in each amplifier, in the ring-shaped traveling wave amplifier the seed is amplified twice in each amplifier, which greatly improves the energy storage utilization rate of each amplifier.

[0038] Those skilled in the art should understand that the present invention can be implemented in many other specific forms without departing from the spirit and scope of the present invention. Based on the embodiments of the present invention, any changes and modifications made by ordinary technicians in the field of the present invention according to the above disclosure are within the scope of protection of the claims.

Claims

1. A side-pumped seed amplified pulse laser, characterized in that: It includes a first seed source and a second seed source arranged opposite to each other, a rotatable 45° reflector between the first seed source and the second seed source, and also includes a first 45° reflector, a filter, a spatial isolator, a plano-concave lens, and a ring-shaped traveling wave amplifier arranged in sequence in the propagation direction of the seed light; The annular traveling wave amplifier comprises a 45° horizontal polarizer after the plano-concave lens, a first traveling wave amplifier after the 45° horizontal polarizer, a half wave plate, a second 45° reflector, a second traveling wave amplifier parallel to the first traveling wave amplifier, and a third 45° reflector and a fourth 45° reflector at both ends of the second traveling wave amplifier; The second 45° reflector can vertically reflect the seed light passing through the half wave plate to the third 45° reflector, the third 45° reflector can vertically reflect the seed light to the second traveling wave amplifier, and the fourth 45° reflector can vertically reflect the seed light passing through the second traveling wave amplifier to the 45° horizontal polarizer, thereby forming a ring-shaped light beam loop.

2. The side-pumped seed amplified pulse laser according to claim 1, characterized in that: It also includes a first beam expander in front of the output end of the first seed source and a second beam expander in front of the output end of the second seed source.

3. The side-pumped seed amplified pulse laser according to claim 2, characterized in that: The first traveling wave amplifier includes a first gain medium between the 45° horizontal polarizer and the half wave plate and a first pump source located on the side of the first gain medium, and the second traveling wave amplifier includes a second gain medium between the third 45° reflector and the fourth 45° reflector and a second pump source located on the side of the second gain medium.

4. The side-pumped seed amplified pulse laser according to claim 3, characterized in that: The first gain medium and the second gain medium are both Nd:YAG crystal rods, the diameter of the crystal rods is 7-8 mm, the length is 80-100 mm, the end face angle is 0.3°-0.5°, and the doping concentration is 0.3 at%-0.5 at%.

5. The side-pumped seed amplified pulse laser according to claim 4, characterized in that: The first pump source and the second pump source are both pulse water-cooled xenon lamps, the inner diameter of the pulse water-cooled xenon lamp is 5-7 mm, and the arc length ranges from 80-100 mm.

6. The side-pumped seed amplified pulse laser according to any one of claims 1 to 5, characterized in that: The 45° rotatable reflector is mounted on a metal servo whose rotation angle is controlled by PWM through a metal plate. The metal servo can drive the 45° rotatable reflector to rotate 45° clockwise or counterclockwise around the servo rotation axis.

7. The side-pumped seed amplified pulse laser according to claim 2, characterized in that: The first beam expander and the second beam expander are both Galilean telescopes. The Galilean telescopes include a concave lens and a convex lens. The distance between the concave lens and the convex lens is 65-75 mm.

8. The side-pumped seed amplified pulse laser according to claim 6, characterized in that: The first seed source is a nanosecond seed source, and the second seed source is a sub-nanosecond seed source. Both the nanosecond seed source and the sub-nanosecond seed source are passively Q-switched lasers.

9. The side-pumped seed amplified pulse laser according to claim 8, characterized in that: The central wavelength output by the passive Q-switched laser is 1064nm, the diameter of the light spot at the light outlet is 0.9-1.0mm, and the beam quality is less than 1.3mm.

10. The side-pumped seed amplified pulse laser according to claim 6, characterized in that: The filter comprises a first polarizer, a second polarizer and a spatially variable wave plate, wherein the first polarizer and the second polarizer are located on both sides of the spatially variable wave plate, and the spatially variable wave plate is a half-wave plate with an optical axis rotated radially.

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