Wavelength measuring device applied to low-repetition-frequency Er: YAG laser therapeutic instrument

Abstract

The utility model relates to a wavelength measuring device applied to a low repetition frequency Er: YAG laser therapeutic instrument, which comprises an incident collimating lens, a laser beam compressor, a convergent lens, a frequency doubling crystal, a crystal adjusting device, an emergent collimating lens, a dichroscope, an emergent convergent lens and a spectrograph, an incident convergent lens is arranged on the right side of the laser beam compressor, a frequency doubling crystal is arranged on the right side of the incident convergent lens and fixed to a crystal adjusting device, an emergent collimating lens is arranged on the right side of the frequency doubling crystal, a dichroic mirror is arranged on the right side of the emergent collimating lens, and an emergent convergent lens is arranged in the reflection direction of the dichroic mirror. And a spectrograph is arranged behind the emergent convergent lens. According to the device, through the second harmonic effect of the frequency doubling crystal, the wavelength of the fundamental frequency Er laser is halved, the wavelength response range of a spectrograph is reached, and wavelength measurement of the low repetition frequency Er: YAG laser therapeutic instrument is achieved.

Description

Technical Field

[0001] The utility model belongs to a laser wavelength measuring device, in particular to a laser wavelength measuring device applied to a low repetition rate Er:YAG therapeutic apparatus. Background Art

[0002] Er:YAG laser therapy device is a solid-state laser doped with yttrium aluminum garnet (Y3Al5O 12 Er:YAG laser therapy device is a medical device with Er:YAG as the light source. The laser therapy device outputs a mid-infrared laser with a wavelength of 2.94μm, which is just near the absorption peak of water (3μm). This wavelength is easily absorbed by water and water-rich human tissues, and has a shallow penetration depth in biological cell tissues, and will not cause burning damage. It has significant biomedical effects. In addition, Er:YAG laser therapy device lasers generally have low repetition frequency and low energy, and are widely used in ophthalmology, dentistry, dermatology and other medical treatments. In order to ensure the safety and effectiveness of medical devices and protect human health and life safety. my country has formulated the "Medical Device Supervision and Management Regulations" and the "Medical Device Registration and Filing Management Measures" which clearly stipulate that medical devices that apply for registration or filing should be inspected in accordance with product technical requirements. Therefore, before clinical application of Er:YAG laser therapy devices, they must be inspected by provincial and above medical device inspection agencies in accordance with their product technical requirements. At present, the national standards for laser medical products mainly include: GB / T 7247.1 Safety of laser products Part 1: Equipment classification and requirements, GB 9706.222 Medical electrical equipment Part 2-22: Special requirements for basic safety and basic performance of laser equipment for surgery, plastic surgery, treatment and diagnosis, GB / T 7247.13 Safety of laser products Part 12: Classification and measurement of laser products, etc. For Er:YAG laser therapeutic devices, they must also be inspected according to the medical industry standard YY 1301-2016 Laser therapeutic equipment Erbium laser therapeutic device. These standards clearly define the basic parameters of laser medical equipment, including: therapeutic laser wavelength, mode, spot size, energy density, maximum pulse power, etc. Among them, laser wavelength is the most basic parameter of laser medical equipment. The wavelength directly affects the penetration depth of laser in the skin, and then affects the scope of application and treatment effect of laser treatment. It is also the basis for determining laser hazard assessment and safety classification, and is one of the parameters that must be measured for all laser medical equipment registration applications and product quality inspections.

[0003] At present, the instruments for measuring laser wavelength mainly include Fabry-Perot interferometer, Fizeau interferometer wavelength meter and Michelson interferometer. Fabry-Perot interferometer is a method of relay measurement using multiple standard tools with different thicknesses. However, this method has high requirements for the thickness calibration of each standard tool in the relay measurement, and a reference beam needs to be introduced into the measurement system, which makes the system more complicated. The patent "A laser wavelength measurement device and method" (publication number CN113607290B) constructs two sets of Fabry-Perot interferometers to coordinate with each other, forms a main and auxiliary measurement interference signal, and calculates the laser wavelength through the principle of optical vernier modulation. The Fizeau interferometer wavelength meter is made of two fused quartz plates and a wedge-shaped spacer glued together. By fixing the wedge angle and spacing on the inner surface of the interference cavity, the initial phase and the width of the interference fringe are measured to obtain the wavelength to be measured. However, due to changes in temperature, air refractive index or wedge-shaped spacer during actual use, a reference light source also needs to be introduced. The patent "Fizeau interferometer wavelength meter and optical device for measuring lasers" (publication number CN114459618B) forms a dense interference fringe image and a sparse interference fringe image by passing two parts of the parallel light beam through a flat plate and then a wedge plate structure, and analyzes the dense interference fringe image data and the sparse interference fringe image data to obtain the wavelength of the incident laser. The Michelson interferometer measures the wavelength by comparing the number of interference fringes of the reference light and the test light, and can only measure the wavelength of a continuous laser. These measurement methods all require the introduction of a standard reference light source, and have high requirements for the light source, which is not conducive to system integration.

[0004] Analysis shows that most of the above-mentioned laser wavelength measurement methods and patents use the interference method, but the interference method requires continuous laser output or repeated pulse output. The laser wavelength output by the low-repetition-rate Er:YAG laser therapy device is in the mid-infrared region, and when the low-repetition-rate single pulse is output, the coherence condition cannot be achieved, so the measurement instrument based on the coherence method has no relevant signal response. The method of directly measuring the laser wavelength through a spectrometer has certain requirements on the applicable wavelength range of the spectrometer. The measurement range of commonly used spectrometers is in the near-infrared region, and it has no response to mid-infrared lasers or has a slow scanning speed. Summary of the invention

[0005] In view of the above problems existing in the prior art, the utility model provides a wavelength measuring device applied to a low repetition rate Er:YAG laser therapeutic apparatus, the purpose of which is to halve the wavelength of the fundamental frequency Er laser through the second harmonic effect of the frequency doubling crystal, thereby measuring the wavelength of the frequency doubling light through a spectrometer to obtain the actual wavelength of the fundamental frequency Er laser, and has the advantages of simple measurement method and fast operation.

[0006] The utility model adopts a technical solution: a wavelength measurement device applied to a low-repetition-rate Er:YAG laser therapeutic apparatus, comprising an incident collimating lens (1), a laser beam reducer (2), a converging lens (3), a frequency doubling crystal (4), a crystal adjustment device (5), an output collimating lens (6), a dichroic mirror (7), an output converging lens (8), and a spectrometer (9). The invention relates to a laser beam reducer (2) having an incident collimating lens (1) arranged at a distance of 5.95 mm from the right side of the laser output window, an incident converging lens (3) arranged at the right side of the laser beam reducer (2), a frequency doubling crystal (4) arranged within the focal length on the right side of the incident converging lens (3), the frequency doubling crystal (4) being fixed on a crystal adjusting device (5), an exit collimating lens (6) arranged at a distance of 5.95 mm from the right side of the frequency doubling crystal (4), a dichroic mirror (7) arranged at the right side of the exit collimating lens (6), the angle between the dichroic mirror (7) and the exit collimating lens (6) being 45°, an exit converging lens (8) arranged in the direction of reflection of the dichroic mirror (7), and a spectrometer (9) being placed at the focus of the exit converging lens (8).

[0007] The incident collimating lens (1) and the output collimating lens (6) are 1 μm-3 μm mid-infrared laser collimating lenses with a diameter of 8 mm and an effective focal length of 5.95 mm.

[0008] The focal length of the incident converging lens (3) is 100 mm.

[0009] The laser beam reducer (2) is a manual laser beam reducer, with an applicable wavelength of 250nm-12μm, a maximum input light spot of 7mm, and an adjustable reduction ratio.

[0010] The focal length of the exit converging lens (8) is 75 mm.

[0011] The spectral response range of the spectrometer (9) is 950nm-1650nm.

[0012] The beneficial effects of the utility model are as follows:

[0013] 1. The optical element combination of incident collimating lens, laser beam reducer and incident converging lens can make the fundamental frequency Er lasers of different low repetition rate Er:YAG laser therapeutic devices enter the frequency doubling crystal under the same conditions.

[0014] 2. By setting the frequency doubling crystal adjustment device, the position of the frequency doubling crystal can be fine-tuned so that the frequency doubling crystal can achieve a better phase matching condition, thereby obtaining a better frequency doubling efficiency and realizing a controllable frequency doubling process.

[0015] 3. By setting a dichroic mirror and an output collimating lens, it can be achieved that only the frequency-doubled light beam is collimated and incident on the output converging lens. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 This is a schematic diagram of the device structure provided by the utility model.

[0017] Figure 2 This is a light path diagram of the device provided by the utility model.

[0018] In the figure: 1. Incident collimating lens; 2. Laser beam reducer; 3. Incident converging lens; 4. Frequency doubling crystal; 5. Crystal adjustment device; 6. Exit collimating lens; 7. Dichroic mirror; 8. Exit converging lens; 9. Spectrometer. DETAILED DESCRIPTION

[0019] The following is a detailed description of the structure and working principle of the utility model:

[0020] Figure 1-Figure 2 The utility model comprises an incident collimating lens 1, a laser beam reducer 2, an incident converging lens 3, a frequency doubling crystal 4, a crystal adjusting device 5, an exit collimating lens 6, a dichroic mirror 7, an exit converging lens 8, and a spectrometer 9; the incident collimating lens 1 has an applicable wavelength of 1 μm-3 μm, a diameter of 8 mm, and an effective focal length of 5.95 mm; the laser beam reducer 2 is located on the right side of the incident collimating lens 1, has an applicable wavelength of 250 nm-12 μm, an input spot of up to 7 mm, and an adjustable reduction ratio; the incident converging lens 3 is located on the right side of the laser beam reducer 2, and has a focal length of 100 mm; the frequency doubling crystal 4 It is located on the right side of the incident converging lens 3 and fixed on the crystal adjustment device 5; the exit collimating lens 6 is located on the right side of the frequency doubling crystal 4, with an applicable wavelength of 1μm-3μm, a diameter of 8mm, and an effective focal length of 5.95mm; the dichroic mirror 7 is located on the right side of the exit collimating lens 6, and the angle between the dichroic mirror 7 and the exit collimating lens 6 is 45°; the exit converging lens 8 is located in the reflection direction of the dichroic mirror 7, and its focal length is 75mm; the spectrometer 9 is located at the focal position of the exit converging lens 8, and its spectral range is 950nm-1650nm; wherein the optical elements are all perpendicular to the optical axis, and their geometric centers are all on the optical axis.

[0021] The measurement process of the utility model is as follows: at a distance of 5.95mm from the left side of the incident collimating lens 1, the fundamental frequency Er laser emitted by the low repetition rate Er:YAG laser therapy device is aligned with the center of the incident collimating lens 1. After being collimated by the incident collimating lens 1, the collimated fundamental frequency Er laser passes through the laser beam reducer 2 to further reduce the diameter of the laser beam. The fundamental frequency Er laser after beam reduction passes through the incident converging lens 3 to converge the fundamental frequency Er laser, thereby increasing the power density of the fundamental frequency light and optimizing the converging conditions of the incident frequency doubling crystal. A frequency doubling crystal 4 is placed within the focal length on the right side of the incident converging lens 3, so that the fundamental frequency Er laser generates a second harmonic effect in the frequency doubling crystal 4 to obtain frequency doubling light. The frequency doubling crystal 4 is fixed on the crystal On the adjustment device 5, the crystal adjustment device 5 is adjusted to fine-tune the phase matching angle between the incident laser and the frequency doubling crystal, thereby improving the crystal frequency doubling efficiency. An output collimating lens 6 is arranged 5.95 mm to the right of the frequency doubling crystal 4 to collimate the divergent light beam emitted by the frequency doubling crystal 4. A dichroic mirror 7 is arranged to the right of the output collimating lens 6. The angle between the dichroic mirror 7 and the output collimating lens 6 is 45°. The baseband Er light and the frequency doubling light are separated by the dichroic mirror 7. An output converging lens 8 is arranged in the reflection direction of the frequency doubling light. A spectrometer 9 is placed at the focus of the output converging lens 8 so that the frequency doubling laser enters the spectrometer 9 to obtain the frequency doubling laser wavelength, thereby obtaining the baseband Er laser wavelength.

Claims

1. A wavelength measurement device for low repetition rate Er:YAG laser therapeutic apparatus, comprising an incident collimating lens (1), a laser beam reducer (2), a converging lens (3), a frequency doubling crystal (4), a crystal adjustment device (5), an output collimating lens (6), a dichroic mirror (7), an output converging lens (8), and a spectrometer (9); wherein: An incident collimating lens (1) is arranged in the laser incident direction, a laser beam reducer (2) is arranged on the right side of the incident collimating lens (1), an incident converging lens (3) is arranged on the right side of the laser beam reducer (2), a frequency doubling crystal (4) is placed on the right side of the incident converging lens (3), and the frequency doubling crystal (4) is fixed on a crystal adjustment device (5); the invention is characterized in that an exit collimating lens (6) is arranged on the right side of the frequency doubling crystal (4), a dichroic mirror (7) is arranged on the right side of the exit collimating lens (6), the angle between the dichroic mirror (7) and the exit collimating lens (6) is 45 degrees, an exit converging lens (8) is arranged in the reflection direction of the dichroic mirror (7), and a spectrometer (9) is placed behind the exit converging lens (8).

2. The wavelength measuring device for low repetition rate Er:YAG laser therapeutic apparatus according to claim 1, characterized in that: The incident collimating lens (1) and the output collimating lens (6) are 1 μm-3 μm mid-infrared laser collimating lenses with a diameter of 8 mm and an effective focal length of 5.95 mm.

3. The wavelength measuring device for low repetition rate Er:YAG laser therapeutic apparatus according to claim 1, characterized in that: The focal length of the incident converging lens (3) is 100 mm.

4. The wavelength measuring device for low repetition rate Er:YAG laser therapeutic apparatus according to claim 1, characterized in that: The laser beam reducer (2) is applicable to a wavelength of 250nm-12μm, has a maximum input light spot size of 7mm, and an adjustable reduction ratio.

5. The wavelength measurement device for low repetition rate Er:YAG laser therapeutic apparatus according to claim 1, characterized in that: The focal length of the exit converging lens (8) is 75 mm.

6. The wavelength measuring device for low repetition rate Er:YAG laser therapeutic apparatus according to claim 1, characterized in that: The spectral response range of the spectrometer (9) is 950nm-1650nm.

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