Nanosecond blue light laser

Abstract

The utility model provides a nanosecond blue light laser. Comprising a first reflecting lens, a quarter-wave plate, a first Q-switching module, a first side pump module, an optical rotation sheet, a second side pump module, a second Q-switching module, a polarizing film, a second reflecting lens, a third reflecting lens, a half-wave plate, a fourth reflecting lens, a beam expanding lens, a first plano-convex lens, a frequency doubling crystal, a color separation lens and a second plano-convex lens which are arranged in sequence. According to the nanosecond blue light laser, a resonant cavity with a novel structure is used, and high-efficiency nanosecond polarized light output with the wavelength of 946 nm is achieved. The LBO frequency doubling crystal is utilized, nanosecond laser with the wavelength of 946 nm is subjected to frequency doubling to form nanosecond blue light with the wavelength of 473 nm, the nanosecond blue light is output, the light beam quality is good, and the power is high.

Description

Technical Field

[0001] The present application relates to the field of laser technology, and in particular to a nanosecond blue laser. Background Art

[0002] At present, blue light is widely used in many fields. For example, in industrial processing applications, according to actual needs, the cleaning of highly reflective materials such as copper and aluminum requires blue light lasers with higher power and higher peak power, and a simpler and more reliable light source. Specific application scenarios may include cutting and welding of highly reflective materials, laser underwater communications, ocean exploration, high-density optical storage, laser display, spectral analysis, bioengineering and laser medical treatment.

[0003] However, the existing blue light output method is to directly output by semiconductor diodes, or to pump solid laser working materials with semiconductor diodes to generate near-infrared fundamental frequency light, and convert the near-infrared laser into visible light wavelength output through nonlinear crystal frequency doubling. Therefore, the current existing technology has the following disadvantages: first, the direct output of semiconductor diodes is continuous light, with low peak power and poor beam quality; second, semiconductor diodes pump laser working materials to generate near-infrared fundamental frequency light, and the blue light power obtained by frequency doubling is low.

[0004] Therefore, there is an urgent need for a blue light laser with high beam quality and high-power output through frequency doubling. Utility Model Content

[0005] The present application provides a nanosecond blue light laser to solve the technical problems of poor beam quality and low power of frequency-doubled output blue light generated in existing blue light lasers.

[0006] The nanosecond blue laser provided by the present application includes: a first reflector, a quarter wave plate, a first Q-switching module, a first side pump module, a polarizer, a second side pump module, a second Q-switching module, a polarizer, a second reflector, a third reflector, a half wave plate, a fourth reflector, a beam expander, a first plano-convex lens, a frequency doubling crystal, a color separation lens and a second plano-convex lens, which are arranged in sequence; wherein the first side pump module, the polarizer and the second side pump module are configured to generate laser light; the first side pump module and the second side pump module are symmetrical about the polarizer, and the first Q-switching module and the second Q-switching module are symmetrical about the polarizer; the third reflector is tilted and configured to adjust the emission direction of the laser light; the third reflector and the fourth reflector are symmetrical about the half wave plate; the reflectivities of the first reflector, the third reflector and the fourth reflector are all greater than the reflectivity of the second reflector.

[0007] In some feasible implementations, the first Q-switching module and the second Q-switching module are both acousto-optic Q-switching modules, the distance between the first Q-switching module and the first side pump module, and the distance between the second Q-switching module and the second side pump module are both 3-6 mm, the first Q-switching module and the second Q-switching module are both coated with a high-transmittance film, and the transmittance of the first Q-switching module and the second Q-switching module are both greater than 99.9%.

[0008] In some feasible implementations, the first reflective mirror is a resonant cavity mirror, and the reflectivity of the first reflective mirror to the laser with a wavelength of 946nm is greater than 99.9%, and the transmittance to the laser with a wavelength of 1064-1320nm is greater than 90.0%; the transmittance of the second reflective mirror to the laser with a wavelength of 946nm is 10%, and the transmittance to the laser with a wavelength of 1064-1320nm is greater than 90%; the third reflective mirror is set at an angle of 45° toward the direction of the second reflective mirror, and the reflectivity of the third reflective mirror to the laser with a wavelength of 946nm is greater than 99.9%; the reflectivity of the fourth reflective mirror to the laser with a wavelength of 946nm is greater than 99.9%.

[0009] In some feasible implementations, the first side pump module and the second side pump module both include a semiconductor diode and a Nd:YAG crystal, the semiconductor diode is configured to generate pump light, and the Nd:YAG crystal is configured to generate a laser with a wavelength of 946 nm under the action of the pump light; wherein the crystal end face transmittance of the first side pump module and the second side pump module are both greater than 99.9%.

[0010] In some feasible implementations, the quarter wave plate is configured to adjust the polarization mode of the resonant cavity, and the transmittance of the quarter wave plate to the laser with a wavelength of 946nm is greater than 99.9%; the half wave plate is configured to adjust the polarization direction of the laser, and the transmittance of the half wave plate to the laser with a wavelength of 946nm is greater than 99.9%; wherein the extension direction of the half wave plate is perpendicular to the extension direction of the quarter wave plate.

[0011] In some possible implementations, the optical rotator is configured to compensate for the thermal birefringence effect of the Nd:YAG crystal, and the transmittance of the optical rotator to the laser with a wavelength of 946 nm is greater than 99.9%.

[0012] In some feasible implementations, the first plano-convex lens is configured to focus a laser with a wavelength of 946nm and inject it into a frequency doubling crystal, and the transmittance of the first plano-convex lens to the laser with a wavelength of 946nm is greater than 99.9%; the frequency doubling crystal is configured to frequency double the laser with a wavelength of 946nm to a laser with a wavelength of 473nm, and both ends of the frequency doubling crystal are coated, and the transmittance to the laser with a wavelength of 946nm is greater than 99.9%, and the transmittance to the laser with a wavelength of 473nm is greater than 99.9%; the second plano-convex lens is configured to collimate the laser with a wavelength of 473nm, and the transmittance of the second plano-convex lens to the laser with a wavelength of 473nm is greater than 99.9%.

[0013] In some feasible implementations, the polarizer is a Brewster polarizer, the polarization ratio of the polarizer is 1000:1, and the transmittance of the polarizer to laser light with a wavelength of 946 nm is greater than 99.9%.

[0014] In some possible implementations, the beam expander is configured to collimate a laser with a wavelength of 946 nm, and the transmittance of the beam expander to the laser with a wavelength of 946 nm is greater than 99.9%.

[0015] In some feasible implementations, the dichroic mirror is configured to separate laser light with a wavelength of 946 nm and laser light with a wavelength of 473 nm, the dichroic mirror is parallel to the fourth reflective lens, the reflectivity of the dichroic mirror to the laser light with a wavelength of 946 nm is greater than 99.9%, and the transmittance of the dichroic mirror to the laser light with a wavelength of 473 nm is greater than 99.9%.

[0016] The nanosecond blue laser provided by the present application uses a resonant cavity of a new structure to achieve high-efficiency nanosecond polarized light output with a wavelength of 946nm. Using LBO frequency-doubling crystals, the nanosecond laser with a wavelength of 946nm is frequency-doubled to a nanosecond blue light output with a wavelength of 473nm, and the beam quality is good and the power is high. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] In order to more clearly illustrate the technical solution of the present application, the drawings required for use in the embodiments are briefly introduced below. Obviously, for ordinary technicians in this field, other drawings can be obtained based on these drawings without any creative work.

[0018] Figure 1 It is a schematic diagram of the structure of a nanosecond blue laser provided in an embodiment of the present application.

[0019] Graphic marking:

[0020] 100-nanosecond blue laser; 1-first reflective lens; 2-quarter wave plate; 3-first Q-switching module; 4-first side pump module; 5-optical rotator; 6-second side pump module; 7-second Q-switching module; 8-polarizer; 9-second reflective lens; 10-third reflective lens; 11-half wave plate; 12-fourth reflective lens; 13-beam expander; 14-first plano-convex lens; 15-frequency doubling crystal; 16-color separation lens; 17-second plano-convex lens. DETAILED DESCRIPTION

[0021] The technical solutions in the embodiments of the present application will be described clearly below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are part of the embodiments of the present application, rather than all of the embodiments. Based on the embodiments of the present application, other embodiments obtained by ordinary technicians in this field without making creative work all belong to the protection scope of the present application.

[0022] In the following, the terms "first", "second", etc. are used for descriptive purposes only and are not to be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Thus, a feature defined as "first", "second", etc. may explicitly or implicitly include one or more of the features. In the description of this application, unless otherwise specified, "plurality" means two or more.

[0023] In addition, in the present application, directional terms such as "upper", "lower", "inner" and "outer" are defined relative to the orientation of the components schematically placed in the drawings. It should be understood that these directional terms are relative concepts. They are used for relative description and clarification, and they can change accordingly according to the changes in the orientation of the components placed in the drawings.

[0024] To facilitate the technical solution of the application, some concepts involved in the application are first explained below.

[0025] Laser gain crystal: In order to form a stable laser during laser operation, there must be luminous particles that can form a population inversion. They can be molecules, atoms or ions. Some of these particles can exist independently, while others exist in certain materials. The material that replaces the ions in the material and provides a storage place for the activated particles is called the matrix. The matrix and the activated particles are collectively called the laser working material, and in solid-state lasers they are called laser gain crystals.

[0026] Quasi-three-level structure: During the operation of the laser, the working material needs to have a metastable structure, that is, a suitable energy level system. The energy level system must first have a laser upper energy level and a laser lower energy level; in addition, some other energy levels related to the generation of lasers are required. Common laser working materials are composed of atomic systems with a metastable three-level structure or a four-level structure. The three-level structure consists of a pumping energy level, a laser upper energy level, and a laser lower energy level. In the three-level structure, the laser lower energy level is the ground state energy level, and laser emission is generated by the transition from the laser upper energy level to the laser lower energy level; the four-level structure consists of a pumping energy level, a laser upper energy level, a laser lower energy level, and a ground state energy level. Since the laser lower energy level in the four-level energy level is not the same energy level as the ground state energy level, the required excitation energy is less than the three-level structure. The quasi-three-level energy level is between the three-level energy level and the four-level energy level. In the laser working material, the doped ions are affected by the crystal field of the matrix material, and the laser upper energy level and the ground state energy level are split to form multiple sub-energy levels around the main energy level. Laser emission is generated by the transition of the laser upper energy level to these sub-energy levels, so it is called a quasi-three-level structure.

[0027] Polarized light: refers to a light wave whose vibration direction of the light vector remains unchanged or has a certain regular change. According to its properties, it can be divided into plane polarized light (linear polarized light), circular polarized light, elliptically polarized light, and partially polarized light. In the embodiments of the present application, there are linear polarized light and circular polarized light. The vibration direction of linear polarized light is a straight line during propagation. According to the difference in the vibration direction being perpendicular to the plane of propagation direction, it can be divided into P polarized light and S polarized light. If the electric vector of a light wave changes regularly over time, that is, the trajectory of the end of the electric vector is circular or elliptical on a plane perpendicular to the propagation direction, it is called circularly polarized light or elliptically polarized light.

[0028] Q-switching: Through artificial control of the laser operation state, the laser energy that is generally output as continuous or pulsed is emitted in the form of pulses in a very short time, so that the output can obtain a peak power output that is several orders of magnitude higher than that of continuous operation. In the artificial control of the laser operation state, the quality factor of the laser resonant cavity, that is, the Q value, is mainly controlled to obtain a pulse output with high peak power. The meaning of the Q value is the ratio of the total energy stored in the laser resonant cavity to the energy lost per unit time in the cavity. Therefore, Q-switching refers to adjusting the size of the Q value, and the common Q-switching method in the laser resonant cavity is to adjust the loss of the resonant cavity, and artificially control the size of the loss to change the Q value of the resonant cavity. The Q-switching process is generally completed in two stages. In the first stage, the loss of the resonant cavity is increased, so that the loss in the cavity is higher than the gain, the Q value is low, and it is difficult to start the laser. In order to start the laser, the inversion density of the upper energy level particle number of the laser will continue to increase. In the second stage, when the inversion density of the upper energy level particle number reaches the maximum, the loss of the resonant cavity is suddenly reduced, so that the Q value increases, and the stimulated emission in the resonant cavity quickly consumes the stored inversion particle number of the upper energy level, generating a laser giant pulse.

[0029] Laser frequency doubling: After a laser beam passes through a nonlinear optical crystal or nonlinear optical material, the frequency of the output laser beam doubles due to the nonlinear effect. This process is called frequency doubling.

[0030] Principle of blue laser emission: Establish a quasi-three-level laser operation system, use a laser with a wavelength of 808nm as a pump beam, pump the particles to the pumping energy level, and then the particles transition from the pumping energy level to the laser upper energy level through non-radiative transition, forming a particle number inversion between the laser upper energy level and the ground state energy level, and the laser upper energy level stimulates radiation to the ground state energy level to form a laser output with a wavelength of 946nm. By adjusting the Q value in the resonant cavity, the laser with a wavelength of 946nm is emitted in the form of nanosecond pulses. After the output nanosecond laser with a wavelength of 946nm is shaped and expanded, it is incident into the LBO frequency doubling crystal through a plano-convex lens. At this time, the laser with a wavelength of 946nm is called the fundamental frequency light. The fundamental frequency light is incident on the LBO frequency doubling crystal to achieve good phase matching conditions. At this time, under the action of nonlinear effects, the laser with a wavelength of 946nm transfers energy to the blue laser with a wavelength of 473nm. This process is called frequency doubling, and finally forms a blue laser output with a wavelength of 473nm.

[0031] The main implementation methods of Blu-ray:

[0032] First, semiconductor diodes directly emit blue light lasers: This method has a simple blue light structure, and emits blue light with a wavelength of 473nm under electrical excitation by growing a semiconductor PN junction structure. Its advantages are simple structure, high efficiency, and the ability to generate high-power blue light through beam combining. Its disadvantages are that the laser is continuous light, with low peak power, and poor beam quality after beam combining.

[0033] Second, near-infrared semiconductor diodes emit lasers that are directly frequency-doubled or frequency-added to produce blue light: a near-infrared semiconductor generates a laser with a wavelength of 946nm, and then a frequency-doubling crystal is used to output blue light with a wavelength of 473nm. This method has high requirements on the power and beam quality of the fundamental frequency light emitted by the semiconductor diode, and is difficult to achieve.

[0034] Third, use semiconductor diode lasers to pump solid laser working materials and use nonlinear crystals to achieve frequency doubling: This method has relatively mature technical accumulation. A nanosecond pulse laser with a wavelength of 946nm is generated through a resonant cavity, and then a nonlinear crystal is used to double the wavelength of the 946nm nanosecond laser to a nanosecond laser output with a wavelength of 473nm.

[0035] Thus, the existing blue light output method has the following disadvantages: First, the semiconductor diode directly outputs continuous light, with low peak power and poor beam quality. Second, the semiconductor diode pumps the laser working material to produce near-infrared fundamental frequency light, and the blue light power obtained by frequency doubling is low.

[0036] To solve the above technical problems, the present application provides a nanosecond blue laser. The nanosecond blue laser mainly includes two components, the first part is a resonant cavity that emits fundamental frequency light with a wavelength of 946nm, and the second part is a frequency doubling module that doubles the fundamental frequency light with a wavelength of 946nm to blue light with a wavelength of 473nm.

[0037] Figure 1 It is a schematic diagram of the structure of the nanosecond blue laser provided in the embodiment of the present application.

[0038] See also Figure 1 The nanosecond blue laser 100 specifically includes a first reflector 1, a quarter wave plate 2, a first Q-switching module 3, a first side pump module 4, a polarizer 5, a second side pump module 6, a second Q-switching module 7, a polarizer 8, a second reflector 9, a third reflector 10, a half wave plate 11, a fourth reflector 12, a beam expander 13, a first plano-convex lens 14, a frequency doubling crystal 15, a color separation lens 16, and a second plano-convex lens 17, which are arranged in sequence. The first side pump module 4, the polarizer 5, and the second side pump module 6 are configured to generate laser light. The reflectivity of the first reflector 1, the third reflector 10, and the fourth reflector 12 are all greater than the reflectivity of the second reflector 9.

[0039] The first reflective mirror 1 is used as a resonant cavity mirror to emit laser light with a wavelength of 946nm generated by stimulated radiation in the resonant cavity, so that it passes through the laser working material again to increase the number of photons with a wavelength of 946nm generated by stimulated radiation. The first reflective mirror 1 is a full reflective mirror with a coating on it, and the high reflectivity R of the laser light with a wavelength of 946nm is greater than 99.9%, and the high transmittance T of the laser light with a wavelength of 1064-1320nm is greater than 90%.

[0040] The quarter wave plate 2 is used to adjust the polarization mode of polarized light in the resonant cavity. The film is coated on it, and the high transmittance T of the laser with a wavelength of 946nm is greater than 99.9%.

[0041] The first Q-switching module 3 and the second Q-switching module 7 are symmetrical about the optical rotator 5, and both can be acousto-optic Q-switching modules. The first Q-switching module 3 and the second Q-switching module 7 are both used to adjust the Q value in the resonant cavity to form nanosecond pulses. In order to improve the shutdown efficiency of the Q-switching module, the distance between the first Q-switching module 3 and the first side pump module 4, and the distance between the second Q-switching module 7 and the second side pump module 6 are as close as possible. The first Q-switching module 3 and the second Q-switching module 7 are coated, and the high transmittance T of the laser with a wavelength of 946nm is greater than 99.9%. Among them, the first Q-switching module 3 and the second Q-switching module 7 are placed orthogonally.

[0042] In some feasible implementations, the distance between the first Q-switching module 3 and the first side pump module 4, and the distance between the second Q-switching module 7 and the second side pump module 6 may all be 3-6 mm.

[0043] For example, the distance may be one of 3 mm, 4 mm, 5 mm or 6 mm. Of course, it may also be other values ​​not shown in the range of 3-6 mm.

[0044] Preferably, the distance is 5 mm, and the distances between the first Q-switching module 3 and the first side pump module 4 , and the distances between the second Q-switching module 7 and the second side pump module 6 are equal.

[0045] The first side pump module 4 and the second side pump module 6 are symmetrical about the optical rotator 5, and semiconductor diodes and Nd:YAG crystals are installed inside the first side pump module 4 and the second side pump module 6. The semiconductor diode is used to generate pump light, and the Nd:YAG crystal is a laser working material, which generates a laser with a wavelength of 946nm under the action of the pump light. The working wavelength of the semiconductor diode is 808nm, the doping concentration of the Nd:YAG crystal is 1.0at%, and the crystal end face is coated. The high transmittance T of the laser with a wavelength of 946nm is greater than 99.9%, and the cooling temperature of the first side pump module 4 and the second side pump module 6 is 10°C.

[0046] The optical rotator 5 is used to compensate for the thermal birefringence effect of the Nd:YAG crystal. The optical rotator 5 is coated with a high transmittance of T>99.9% for lasers with a wavelength of 946 nm.

[0047] Polarizer 8 is a Brewster polarizer, which is used as a polarizer in the resonant cavity, has high transmittance for P polarized light and high reflection for S polarized light, and a polarization ratio of 1000:1. It is coated with a high transmittance T>99.9% for laser with a wavelength of 946nm. The tilt angle of polarizer 8 is the Brewster angle.

[0048] The second reflective lens 9 is a partial reflective lens, which serves as a cavity mirror of the resonant cavity, and is used to reflect the laser with a wavelength of 946nm generated by stimulated radiation in the resonant cavity, so that it passes through the laser working material again, increasing the number of photons with a wavelength of 946nm generated by stimulated radiation, and allowing part of the laser with a wavelength of 946nm to pass through, forming laser emission. The second reflective lens 9 is coated with a film, and the partial transmittance T of the laser with a wavelength of 946nm is 10%, the reflectance is 90%, and the high transmittance T of the laser with a wavelength of 1064-1320nm is>90%.

[0049] The third reflector 10 is used to change the emission direction of the laser with a wavelength of 946nm. The third reflector 10 is coated and the third reflector 10 is inclined at an angle of 45° toward the second reflector 9. The high reflectivity R of the laser with a wavelength of 946nm at 45° incidence is greater than 99.9%.

[0050] The half wave plate 11 is used to adjust the polarization direction of the laser output light with a wavelength of 946nm to match the crystal axis of the frequency doubling crystal 15. The half wave plate 11 is coated to make the high transmittance T of the laser with a wavelength of 946nm greater than 99.9%.

[0051] The fourth reflective lens 12 and the third reflective lens 10 are symmetrically arranged with respect to the half wave plate 11, and are used to change the propagation direction of the laser with a wavelength of 946 nm, and the high reflectivity R of the laser with a wavelength of 946 nm is greater than 99.9%.

[0052] Specifically, the extension direction of the half wave plate 11 is perpendicular to the extension direction of the quarter wave plate 2. Figure 1 , the quarter wave plate 2 is arranged vertically, and the half wave plate 11 is arranged horizontally, so that the emission direction of the laser can be changed by the inclined third reflector 10, the half wave plate 11 and the fourth reflector 12. In other words, before reaching the third reflector 10, the laser is emitted from the direction of the second reflector 9 along the polarizer 8, and after passing through the third reflector 10, the half wave plate 11 and the fourth reflector 12, the emission direction is changed, and it is emitted from the direction of the beam expander 13 to the first plano-convex lens 14, that is, the direction of the second reflector 9 to the polarizer 8. In this way, the purpose of setting each lens is to reasonably plan the internal space of the nanosecond blue laser 100 to avoid waste and redundancy of the installation space.

[0053] It can be understood that in the nanosecond blue laser, the first reflective lens 1, the third reflective lens 10 and the fourth reflective lens 12 are coated on one side, and the remaining lenses are coated on both sides. Among them, the first reflective lens 1 is coated on the side facing the quarter wave plate 2, and the third reflective lens 10 and the fourth reflective lens 12 are coated on the side facing the half wave plate 11.

[0054] The beam expander 13 is used to collimate the laser with a wavelength of 946nm, expand the spot area, and improve the frequency doubling efficiency and stability. The lens coating of the beam expander 13 makes the high transmittance T of the laser with a wavelength of 946nm greater than 99.9%.

[0055] The first plano-convex lens 14 is used to focus the laser with a wavelength of 946 nm into the frequency doubling crystal 15. The first plano-convex lens 14 is coated to make the high transmittance T of the laser with a wavelength of 946 nm greater than 99.9%.

[0056] The frequency doubling crystal 15 is used to double the wavelength of 946nm laser to output a wavelength of 473nm laser. Both ends of the crystal are coated with a high transmittance T>99.9% for the wavelength of 946nm laser and a high transmittance T>99.9% for the wavelength of 473nm laser.

[0057] The dichroic lens 16 is used to separate the laser with a wavelength of 946nm and the laser with a wavelength of 473nm passing through the frequency doubling crystal 15. Both ends of the dichroic lens 16 are coated, and the dichroic lens 16 is parallel to the fourth reflective lens 12. In other words, the dichroic lens 16 is tilted 45° toward the direction of the frequency doubling crystal 15, and the high reflectivity R of the laser with a wavelength of 946nm is greater than 99.9% and the high transmittance T of the laser with a wavelength of 473nm is greater than 99.9% at an incident angle of 45°.

[0058] The second plano-convex lens 17 is used to collimate the laser light with a wavelength of 473 nm. The second plano-convex lens 17 is coated with a high transmittance T of the laser light with a wavelength of 473 nm>99.9%.

[0059] Specifically, copper and other metals have a high reflectivity in the near-infrared band, which affects the application of lasers on them such as cleaning and welding. Therefore, it is necessary to use short-wavelength lasers such as blue light. Currently, blue light lasers generally use semiconductor diodes to directly emit coupled optical fibers for output. Semiconductor diodes output blue light as continuous light. When high peak power blue light is required for cleaning and other operations, continuous light is limited because it cannot reach the peak power required for the removal threshold.

[0060] The nanosecond blue laser 100 provided in the embodiment of the present application uses semiconductor side pumping to generate nanosecond laser with a wavelength of 946nm, and uses a resonant cavity with a new structure to achieve high-efficiency nanosecond polarized light output with a wavelength of 946nm. The LBO frequency doubling crystal 15 is used to frequency-double the nanosecond laser with a wavelength of 946nm to output nanosecond blue light with a wavelength of 473nm. In other words, the nanosecond blue laser 100 provided in the embodiment of the present application can simultaneously output nanosecond laser with a high-efficiency polarized wavelength of 946nm and nanosecond blue light with a wavelength of 473nm with high peak power, and the beam quality is good.

[0061] It should be noted that those skilled in the art will easily think of other embodiments of the present application after considering the specification and practicing the application disclosed herein. The present application is intended to cover any modification, use or adaptation of the present application, which follows the general principles of the present application and includes common knowledge or customary technical means in the art that are not disclosed in the present application. The specification and examples are only regarded as exemplary, and the true scope of the present application is indicated by the claims.

[0062] It should be understood that the present application is not limited to the precise structures that have been described above and shown in the drawings, and that various modifications and changes may be made without departing from the scope thereof. The scope of the present application is limited only by the appended claims.

Claims

1. A nanosecond blue laser, characterized in that: include: A first reflective lens, a quarter wave plate, a first Q-switching module, a first side pump module, an optical rotator, a second side pump module, a second Q-switching module, a polarizer, a second reflective lens, a third reflective lens, a half wave plate, a fourth reflective lens, a beam expander, a first plano-convex lens, a frequency doubling crystal, a color separation lens, and a second plano-convex lens are sequentially arranged; Among them, the first side pump module, the optical rotator and the second side pump module are configured to generate laser; the first side pump module and the second side pump module are symmetrical about the optical rotator, and the first Q-switching module and the second Q-switching module are symmetrical about the optical rotator; the third reflector is tilted and configured to adjust the emission direction of the laser; the third reflector and the fourth reflector are symmetrical about the half wave plate; the reflectivities of the first reflector, the third reflector and the fourth reflector are all greater than the reflectivity of the second reflector.

2. The nanosecond blue laser according to claim 1, characterized in that: The first Q-switching module and the second Q-switching module are both acousto-optic Q-switching modules, the distance between the first Q-switching module and the first side pump module, and the distance between the second Q-switching module and the second side pump module are both 3-6 mm, the first Q-switching module and the second Q-switching module are both coated with high-transmittance films, and the transmittance of the first Q-switching module and the second Q-switching module are both greater than 99.9%.

3. The nanosecond blue laser according to claim 1, characterized in that: The first reflective lens is a resonant cavity mirror, and the reflectivity of the first reflective lens to the laser with a wavelength of 946nm is greater than 99.9%, and the transmittance to the laser with a wavelength of 1064-1320nm is greater than 90.0%; The transmittance of the second reflective lens to the laser with a wavelength of 946 nm is 10%, and the transmittance to the laser with a wavelength of 1064-1320 nm is greater than 90%; The third reflective lens is arranged to be inclined at 45° toward the direction of the second reflective lens, and the reflectivity of the third reflective lens to the laser with a wavelength of 946 nm is greater than 99.9%; The reflectivity of the fourth reflective lens to laser light with a wavelength of 946 nm is greater than 99.9%.

4. The nanosecond blue laser according to claim 1, characterized in that: The first side pump module and the second side pump module both include a semiconductor diode and a Nd:YAG crystal, the semiconductor diode is configured to generate pump light, and the Nd:YAG crystal is configured to generate a laser with a wavelength of 946 nm under the action of the pump light; wherein the crystal end face transmittance of the first side pump module and the second side pump module is both greater than 99.9%.

5. The nanosecond blue laser according to claim 1, characterized in that: The quarter wave plate is configured to adjust the polarization mode of the resonant cavity, and the transmittance of the quarter wave plate to the laser with a wavelength of 946nm is greater than 99.9%; The half wave plate is configured to adjust the polarization direction of the laser, and the transmittance of the half wave plate to the laser with a wavelength of 946nm is greater than 99.9%; wherein the extension direction of the half wave plate is perpendicular to the extension direction of the quarter wave plate.

6. The nanosecond blue laser according to claim 4, characterized in that: The optical rotator is configured to compensate for the thermal birefringence effect of the Nd:YAG crystal, and the transmittance of the optical rotator to the laser with a wavelength of 946 nm is greater than 99.9%.

7. The nanosecond blue laser according to claim 1, characterized in that: The first plano-convex lens is configured to focus the laser with a wavelength of 946 nm and inject it into the frequency doubling crystal, and the transmittance of the first plano-convex lens to the laser with a wavelength of 946 nm is greater than 99.9%; The frequency doubling crystal is configured to double the wavelength of a laser with a wavelength of 946 nm to a laser with a wavelength of 473 nm. Both ends of the frequency doubling crystal are coated with a film, and the transmittance of the laser with a wavelength of 946 nm is greater than 99.9%, and the transmittance of the laser with a wavelength of 473 nm is greater than 99.9%; The second plano-convex lens is configured to collimate laser light with a wavelength of 473 nm, and the transmittance of the second plano-convex lens to the laser light with a wavelength of 473 nm is greater than 99.9%.

8. The nanosecond blue laser according to claim 1, characterized in that: The polarizer is a Brewster polarizer, the polarization ratio of the polarizer is 1000:1, and the transmittance of the polarizer to laser with a wavelength of 946nm is greater than 99.9%.

9. The nanosecond blue laser according to claim 1, characterized in that: The beam expander is configured to collimate a laser with a wavelength of 946 nm, and the transmittance of the beam expander to the laser with a wavelength of 946 nm is greater than 99.9%.

10. The nanosecond blue laser according to claim 1, characterized in that: The dichroic mirror is configured to separate laser light with a wavelength of 946 nm and laser light with a wavelength of 473 nm. The dichroic mirror is parallel to the fourth reflective lens. The reflectivity of the dichroic mirror to the laser light with a wavelength of 946 nm is greater than 99.9%, and the transmittance of the dichroic mirror to the laser light with a wavelength of 473 nm is greater than 99.9%.

Images