Dual-wavelength picosecond ultrafast laser skin treatment instrument

Abstract

The application provides a kind of dual-wavelength picosecond ultrafast laser skin treatment instrument, host computer is composed of picosecond laser, light guide system includes light guide arm and treatment handle, the picosecond laser is built into host computer, it includes SESAM passive mode-locked seed laser, regenerative amplifier and beam transmission module;The seed laser adopts the resonant cavity arranged in double Z shape, obtains the stable output mode-locked picosecond laser, is amplified after doubling regenerative amplifier through nonlinear crystal LBO to generate 1064 nm fundamental frequency light and 532 nm frequency-doubled light dual-wavelength output;After expansion system, dichroic mirror group and 532 nm / 1064 nm dual-band beam combiner, the dual-wavelength output spot diameter 0.01-5 mm continuous adjustable is realized.The laser skin treatment instrument of the application is compact in structure, the mode-locked pulse obtained is stable, and the amplified beam quality is high.

Description

Technical Field

[0001] This invention relates to the field of laser medical equipment technology, specifically to a skin treatment device based on dual-wavelength picosecond laser. Background Technology

[0002] Current laser skin treatment technology faces the following key problems:

[0003] 1. The contradiction between thermal damage and treatment efficiency: Conventional Q-switched lasers (nanosecond pulse width) are prone to causing cumulative thermal damage to the epidermis due to their long thermal relaxation time. While some picosecond laser devices have shorter pulse widths, they are still limited by high single-pulse energy, large pulse width, and long action time, resulting in low peak power; poor energy consistency between single pulses leads to greater trauma to the lesion area and poor clinical efficacy.

[0004] 2. Limited beam flexibility: Existing beam transmission systems mostly rely on fixed beam expansion ratios or mechanical apertures to adjust the beam size, which cannot continuously adjust the beam size in real time during treatment. Furthermore, energy loss and mode mismatch are easily introduced when combining two wavelengths.

[0005] 3. Insufficient dual-wavelength coordinated control: Traditional equipment often uses independent lasers to output different wavelengths in a time-division manner, which has problems such as poor timing synchronization and narrow energy ratio adjustment range (usually a fixed ratio), making it difficult to achieve synchronous and precise treatment of deep and superficial tissues.

[0006] In addition, existing technologies also have the following technical bottlenecks:

[0007] 1) Laser source limitations: Traditional medical picosecond lasers have poor stability and short lifespan.

[0008] 2) Energy regulation defects: Traditional medical picosecond lasers are mostly used in low repetition frequency (Hz level) lasers, which lack the ability to independently regulate the energy of dual wavelengths.

[0009] 3) Shortcomings in optical path design: In dual-wavelength scenarios, optical guide arms or fiber optic transmission schemes have problems such as mismatch between reflection and transmission spectra and low damage threshold, which restrict the clinical application of high-energy picosecond lasers. Summary of the Invention

[0010] In view of this, and in order to overcome the shortcomings of the prior art, this invention provides a dual-wavelength picosecond ultrafast laser skin treatment device. This invention innovatively integrates SESAM passive mode-locked seed laser regeneration amplification and dynamic spot transmission technology, breaking through the aforementioned technical bottlenecks in the prior art and solving key technical problems.

[0011] The present invention provides a dual-wavelength picosecond ultrafast laser skin treatment device, the treatment device including a main unit and a light guide system, the main unit including a picosecond laser and a control system, the light guide system including a light guide arm and a treatment handle, the treatment handle being disposed at the free end of the light guide arm and connected to the main unit through the light guide arm;

[0012] The picosecond laser is built into the host unit and includes a SESAM passive mode-locked seed laser, a regenerative amplifier, and a beam transmission module.

[0013] The SESAM passive mode-locked seed laser uses a single-tube semiconductor laser as the pump source and obtains stable output of mode-locked picosecond lasers B and C through a resonant cavity arranged in a double Z-shape.

[0014] The regenerative amplifier is a regenerative amplifier with doubled resonant cavity. The 1064nm fundamental frequency light E output by the mode-locked picosecond laser B through the regenerative amplifier is frequency doubled by the nonlinear crystal LBO, and simultaneously outputs dual wavelengths of 1064nm fundamental frequency light and 532nm frequency doubled light.

[0015] The beam transmission module includes a beam expander, a dichroic mirror group, and a 532 nm / 1064 nm dual-band beam combiner, enabling the dual-wavelength output beam spot diameter to be continuously adjustable from 0.01 to 5 mm.

[0016] One end of the light guide arm is connected to the output end of the dual-band beam combiner, and the other end is provided with a treatment handle. The output laser generated by the dual-band beam combiner is transmitted through the light guide arm and then output through the center of the treatment handle.

[0017] A dynamic focusing scanning galvanometer containing X / Y axis scanning lenses is installed in the end joint of the light guide arm.

[0018] Furthermore, the SESAM passive mode-locked seed laser injects pump light with a power range of 1W-10W, and outputs two mode-locked beams, each with a power range of 0.1W-4W; one of the mode-locked beams is selected to be 70MHz-120MHz, with a single pulse energy of 10-500nJ, which enters the regenerative amplifier for amplification.

[0019] The output light frequency after being amplified by the regenerative amplifier is 50kHz-800kHz, and the single pulse energy is adjustable from 10-300 microjoules.

[0020] The incident light of the regenerative amplifier forms a 180° angle with the amplified output light.

[0021] Furthermore, the treatment handpiece outputs a treatment-use mode-locked picosecond laser ultrashort pulse, a single pulse.

[0022] The average pulse width is 1-15 ps, the energy difference between single pulses at the same transmission frequency is ≤±2%, the peak power of a single pulse is 0.4-240.0 megawatts, and the peak power difference between pulses is ≤±3%.

[0023] Furthermore, the dichroic mirror assembly includes:

[0024] The first dichroic mirror, when incident at 45°, has high reflectivity (R>99.8%) for 1064 nm and high transmittance (T>95%) for 532 nm.

[0025] The second dichroic mirror, when incident at 45°, has high reflectivity (R>99.5%) for 532 nm and high transmittance (T>95%) for 1064 nm.

[0026] The energy ratio of the two wavelengths can be continuously adjusted within the range of 1:1 to 10:1 by rotating the angles of the first and second dichroic mirrors respectively.

[0027] Furthermore, the treatment handpiece has a built-in treatment control module that integrates a skin impedance detection sensor, a pulse energy closed-loop feedback unit, and a multi-wavelength collaborative triggering circuit, supporting dual-wavelength independent or alternating output modes.

[0028] Furthermore, the treatment control module also includes a pulse sequence generation unit and a lesion identification unit;

[0029] The pulse sequence generation unit supports 1064 nm single-wavelength mode, 532 nm single-wavelength mode and dual-wavelength alternating mode, with an adjustable alternation frequency of 1-100 Hz;

[0030] The lesion identification unit automatically matches wavelength selection strategies based on multispectral imaging data, wherein:

[0031] The 1064 nm pulse is preferentially activated in melanin-targeting tissues.

[0032] 532 nm pulses are preferentially activated for hemoglobin-targeting tissues;

[0033] The dual-wavelength alternation mode is used for the treatment of complex lesions.

[0034] Furthermore, the dynamic focusing scanning galvanometer includes a high-speed Galvo scanning head, an adaptive focusing lens group, and a spot shape control unit, wherein: the maximum scanning speed of the high-speed Galvo scanning head is ≥3m / s;

[0035] The adaptive focusing lens group has a focal length adjustment range of 10-150 mm and a response time of <5 ms;

[0036] The spot shape control unit supports dynamic switching between circular, square, and linear spots.

[0037] Furthermore, the control system includes a pulse parameter optimization algorithm module, which calculates the photothermal damage threshold in real time based on Monte Carlo simulation, dynamically adjusts the combination of pulse energy and repetition frequency, and ensures that the thermal relaxation time (TRT) is controlled within the range of 0.1-10 ms.

[0038] Furthermore, each joint of the light guide arm has a built-in position encoder that provides real-time feedback of angular deviations to the control system.

[0039] The system uses an adaptive PID algorithm to compensate for optical path offset in the galvanometer.

[0040] Furthermore, a safety protection unit is provided on the outer surface of the treatment handle, including a contact cooling window, a real-time epidermal temperature monitoring probe, and an automatic pulse over-limit cutoff device. The contact cooling window adopts a modular quick-release design and is electrically connected to the handle body through spring pin contacts. The cooling window has a diameter of 20 mm and a pressure adjustment range of 0.5-2 N / cm². The temperature monitoring probe is arranged in a ring array around the cooling window, containing 8 miniature infrared sensors with a sampling rate of 1 kHz and a spatial resolution of 50 μm.

[0041] The beneficial effects of this invention are as follows:

[0042] 1. The dual-wavelength picosecond ultrafast laser skin treatment device of this invention utilizes a SESAM passive mode-locked seed laser with a double Z-shaped resonant cavity arrangement. This structure is simple and compact, enabling the generation of stable mode-locked pulses. The incident seed light, amplified once by the regenerative amplifier with doubled resonant cavity, passes through the LD-pumped laser crystal module four times, greatly improving amplification efficiency. Furthermore, the resonant cavity has a small geometric volume and high beam quality, making it ideal for the portable, stable, and high beam quality requirements of skin treatment devices.

[0043] 2. This invention achieves high-power synchronous output (single pulse energy 1 μJ-1 mJ) with dual wavelengths (1064 / 532 nm) by using SESAM self-stabilized mode-locked regenerative amplification and LBO crystal cascade frequency doubling.

[0044] 3. The laser skin treatment device of the present invention can ensure that the thermal relaxation time (TRT) is controlled within the range of 0.1-10 ms, taking into account both high energy and high precision treatment requirements.

[0045] 4. This invention is based on uniform high-energy single-pulse operation with a single pulse width of 1-15ps. The energy difference between single pulses is ≤±2%, and the difference in peak power between pulses is ≤±3%. It has stable working performance, high consistency, short action time / low damage, and can effectively solve the problems of safety, consistency and effectiveness of laser skin treatment. The absorption peak of pigment in the lesion area is better than that of traditional methods, the absorption consistency is higher, it can quickly metabolize and reduce recurrence, and it can quickly recover and recover faster after treatment.

[0046] 5. This invention realizes an integrated optical path for beam expansion, color separation, and beam combining, and combined with a dynamic focusing scanning galvanometer, achieves real-time adaptive control of spot size and energy distribution.

[0047] 6. This invention achieves differentiated treatment of the epidermis and dermis by introducing a polarization beam combiner and combining skin impedance feedback data to adjust the wavelength output timing in real time. Data shows that the treatment time is shortened by at least 50%. Attached image description:

[0048] Figure 1 : Schematic diagram of the appearance of the dual-wavelength picosecond ultrafast laser skin treatment device of the present invention

[0049] The components are: 1-Main unit, 2-Light guiding system, 3-Foot switch, 4-Picosecond laser, 5-Power supply, 6-Control system, 7-Cooling system, 8-Light guiding arm, 9-Treatment handpiece;

[0050] Figure 2 : An optical path structure diagram of one embodiment of the laser of the present invention

[0051] Among them: 10-SESAM passive mode-locked seed laser, 101-single-tube semiconductor laser, 102-self-focusing lens, 103-laser crystal, 104-plano-concave mirror a, 105-plano-concave mirror b, 106-plane mirror, 107-output mirror, 108-SESAM saturable absorber mirror.

[0052] 11-Regenerative amplifier; 111-Second polarizer; 112-First quarter-wave plate; 113-Pulse selection switch (1131-Pockmarked cell; 1132-Pockmarked cell high-voltage drive); 114-First 0° total reflection mirror; 115-Third polarizer; 116-Second quarter-wave plate; 117-Pinhole aperture; 118-LD pump laser crystal module; 119-Third quarter-wave plate; 1110-Convex mirror; 1111-Second 0° total reflection mirror; 121-First polarizer; 122-Faraday rotator; 123-Half-wave plate; 13-45° total reflection mirror;

[0053] A - Output light from the mode-locked seed laser resonator; B - Output light from the mode-locked seed laser resonator.

[0054] C - Output light from the mode-locked seed laser resonator cavity; D - Oscillating light within the mode-locked seed laser resonator cavity; E - Amplified output light from the regenerative amplifier.

[0055] Figure 3 One configuration of the beam transmission module of the present invention

[0056] Among them: Lens 1 - First dichroic mirror, Lens 2 - Second dichroic mirror. Detailed Implementation

[0057] The following description, in conjunction with the accompanying drawings and specific embodiments, further explains the present invention of a dual-wavelength picosecond ultrafast laser skin treatment device, but the present invention is not limited to the following embodiments.

[0058] Example 1: A dual-wavelength picosecond ultrafast laser skin treatment device of the present invention

[0059] The present invention discloses a dual-wavelength picosecond ultrafast laser skin treatment device, which consists of a main unit 1, a light guide system 2 and a foot switch 3. The main unit consists of a picosecond laser 4, a power supply 5, a control system 6 and a cooling system 7. The light guide system consists of a light guide arm 8 and a treatment handle 9. The treatment handle 9 is located at the free end of the light guide arm 8 and is connected to the main unit 1 through the light guide arm 8.

[0060] The picosecond laser 4 is built into the host and includes a SESAM passive mode-locked seed laser 10, a regenerative amplifier 11, and a beam transmission module.

[0061] The SESAM passive mode-locked seed laser 10 uses a single-tube semiconductor laser 101 as the pump source, and obtains stable output of mode-locked picosecond lasers B and C through a resonant cavity arranged in a double Z-shape.

[0062] The regenerative amplifier 11 is a regenerative amplifier with doubled resonant cavity, and the mode-locked picosecond laser B...

[0063] The 1064 nm fundamental frequency light E output by the regenerative amplifier 11 is frequency doubled by the nonlinear crystal LBO, and simultaneously outputs dual wavelengths of 1064 nm fundamental frequency light and 532 nm frequency doubled light.

[0064] The beam transmission module includes a beam expander, a dichroic mirror group, and a 532 nm / 1064 nm dual-band beam combiner, enabling the dual-wavelength output beam spot diameter to be continuously adjustable from 0.1 to 5 mm.

[0065] One end of the light guide arm 8 is connected to the output end of the dual-band beam combiner, and the other end is provided with a treatment handle 9. The output laser generated by the dual-band beam combiner is transmitted through the light guide arm 8 and then output through the center of the treatment handle 9.

[0066] A dynamic focusing scanning galvanometer containing X / Y axis scanning lenses is installed in the end joint of the light guide arm.

[0067] Example 2: Optical path structure of the SESAM passive mode-locked seed laser and regenerative amplifier of the present invention

[0068] The self-focusing lens 102 of the SESAM passive mode-locked seed laser 10 is placed between the single-tube semiconductor laser 101 and the laser crystal 103; a plano-concave mirror a104 is placed on the other side of the laser crystal 103, and the light path passes through the center of the laser crystal and enters the focal point of the plano-concave mirror a104 before incident; a plane mirror 106 is placed at the focal point of the light path after reflection by the plano-concave mirror a104, and the angle between the incident light and the reflected light of the plano-concave mirror a104 is in the range of 0 to 10°; the light path, after passing through the laser crystal, the plano-concave mirror a104, and the plane mirror 106, forms a positive Z-shaped structure; symmetrically, the output mirror 107, the plano-concave mirror b105, and the SESAM saturable absorber mirror 108 form an inverse Z-shaped structure. The structure is as follows: the plane mirror 106 and the output mirror 107 are arranged horizontally, the output mirror 107 is placed on the horizontal line reflected by the plane mirror 106 in the light path, the plane mirror 106 is located at the focal point before the incident light from the plane-concave mirror b105, and the SESAM saturable absorber mirror 108 is located at the focal point after the incident light from the plane-concave mirror b105. The angle between the incident light and the reflected light from the plane-concave mirror b105 is in the range of 0 to 10°. The refracted light from the plane-concave mirror b105 is horizontally incident on the surface of the SESAM saturable absorber mirror 108. The positive Z-shaped structure and the negative Z-shaped structure together constitute a double Z-shaped symmetrical arrangement structure of the resonant cavity.

[0069] A, B, and C are the output beams of the mode-locked seed laser resonator; D is the oscillating beam within the mode-locked seed laser resonator. The pump beam power injected into the mode-locked seed laser is 1W-10W, and the output beams B and C each have a power of 0.1W-4W. One of the mode-locked beams, B, is selected to be 70MHz-120MHz, with a single pulse energy of 10-500nJ, and is injected into the regenerative amplifier 12 for amplification.

[0070] The mode-locked seed light B is mode-matched with the injected regenerative amplifier 12 regenerative resonant cavity to obtain the required amplification.

[0071] The regenerative resonant amplification cavity includes a second polarizer 111, a first quarter-wave plate 112, a first 0° total reflection mirror 114, a pulse selection switch 113, a second 0° total reflection mirror 1111, a third polarizer 115, a second quarter-wave plate 116, a pinhole aperture 117, an LD pump laser crystal module 118, a third quarter-wave plate 119, and a convex mirror 1110;

[0072] The incident mode-locked seed light B is introduced into the regenerative resonant amplification cavity through an optical isolator (composed of a first polarizer 121, a Faraday rotator 122, and a half-wave plate 123) for resonant amplification. Its depolarization is compensated by the third quarter-wave plate 119, and the convex mirror 1110 compensates for the thermal lensing effect. The pinhole aperture 117 filters out higher-order modes of the amplified light, ensuring the beam quality of the incident seed amplified light. The third polarizer 115, the second quarter-wave plate 116, the convex mirror 1110, and the second 0° total reflection mirror 1111 achieve optical path lengthening of the incident seed light within the regenerative resonant amplification cavity. Controlled by the pulse selection switch 113, the amplified seed light is exported from the regenerative resonant amplification cavity. After total internal reflection by the 45° total reflection mirror 13, the regenerated amplified light E is output from the outlet.

[0073] The frequency of the regenerated amplified light E is 50kHz-80kHz, and the single pulse energy is adjustable from 10 to 300 microjoules; the mode-locked light B forms a 180° angle with the regenerated amplified light E.

[0074] The cavity length of the regenerative amplifier 11 with doubled resonant cavity is an integer multiple of the cavity length 10 corresponding to the spacing of the incident mode-locked picosecond laser seed pulses, where the multiple is the number of regenerated and amplified outputs of the selected mode-locked seed pulses after passing through the regenerative resonant amplifier cavity.

[0075] Example 3: LBO frequency multiplication structure of the present invention:

[0076] The LBO frequency doubling structure of this invention includes an LBO crystal and a temperature control device. The LBO crystal has dimensions of 4×4×15 mm³, a cutting angle of θ=32°, and φ=0°. It has Class I phase matching: 1064 nm→532 nm. The crystal is placed in an aluminum heat sink, and the temperature is controlled at 35±0.1℃ by TEC to ensure phase matching. The LBO frequency doubling conversion efficiency is: when the input 1064 nm optical power is 2 W, the output 532 nm power is 0.8 W (conversion efficiency 40%), and the total power of the two wavelengths is 2.8 W.

[0077] Example 4: Structure of the beam transmission module of the present invention:

[0078] It includes a beam expander system, a dichroic mirror group, and a 532 nm / 1064 nm dual-band beam combiner.

[0079] like Figure 3 As shown, a Galilean beam expander with a beam expansion ratio of 1:5 is used to pre-expand and collimate the mixed wavelength laser source. After the beam passes through the energy ratio adjustment module, it passes through the beam shaping and beam combining output module. The 532 nm / 1064 nm beams pass through variable magnification beam expanders to continuously adjust the output spot diameter, achieving a continuously adjustable output spot diameter of 0.1-5 mm.

[0080] The dichroic mirror assembly includes a first dichroic mirror (lens 1) mounted on a rotating stage 1 and a second dichroic mirror (lens 2) mounted on a rotating stage 2: The first dichroic mirror has high reflectivity (R>99.8%) for 1064 nm and high transmittance (T>95%) for 532 nm when incident at 45°; the second dichroic mirror has high reflectivity (R>99.5%) for 532 nm and high transmittance (T>95%) for 1064 nm when incident at 45°; the lenses are mounted on the rotating stage (angular resolution 0.01°), and the dynamic adjustment of the dual-wavelength energy ratio is achieved by changing the incident angle of the lenses through the rotation of the rotating stage.

[0081] The dynamic adjustment mechanism of the dual-wavelength energy ratio is as follows:

[0082] Variable 1 (P1064-path1): The 1064nm energy from path 1 that ultimately participates in beam combining (controlled by the reflectivity of the first dichroic mirror at 1064nm).

[0083] Variable 2 (P532-path2): The 532nm energy from path 2 that ultimately participates in the beam combining (controlled by the transmittance of the first dichroic mirror to 532nm and the reflectance of the second dichroic mirror to 532nm).

[0084] The final beam output ratio (1064nm:532nm) = P1064-path1:P532-path2.

[0085] When a 1:1 output is required, P1064-path1=P532-path2;

[0086] By reducing the incident angle of the first dichroic mirror, its reflectivity at 1064nm is reduced, thereby decreasing P1064-path1. At the same time, this angle change will also affect P532-path2, but through precise adjustment, a balance point can be found to make the two equal.

[0087] When a 10:1 output is required, P1064-path1=10×P532-path2;

[0088] By increasing the incident angle of the first dichroic mirror, its reflectivity at 1064nm is maximized, thereby...

[0089] P1064-path1 is close to its maximum value; at the same time, this angle will change the transmittance of the first dichroic mirror to 532nm and may reduce the reflectance of the second dichroic mirror to 532nm, thereby reducing P532-path2; with one increase and one decrease, a high ratio of 10:1 can be easily achieved.

[0090] Dual-band beam combiner: Polarization beam combiner (PBC) is combined with wavelength beam combiner. The 1064 nm light is rotated and polarized by a λ / 2 waveplate and then orthogonally polarized and combined with the 532 nm light. The total loss of the dual wavelengths is <5%, and the divergence angle of the output beam is <0.5 mrad.

[0091] Verification of light spot control:

[0092] Minimum spot size:

[0093] The system operates in beam-shrinking mode. The beam is first pre-processed by a 5x beam expander and collimator, then reduced in diameter by an adjustable beam expander, and finally focused using the last lens assembly of the beam expander (equivalent focal length f=50mm), achieving a minimum spot diameter of approximately 0.1 mm. Power density >100 GW / cm²;

[0094] Maximum beam size: The system can directly output a collimated beam of 5 mm. After beam shaping, a flat-top distribution with a uniformity of >90% is obtained.

[0095] Switching speed: Response time for changes in spot diameter <100 ms (stepper motor drives lens displacement).

[0096] The beam transmission module of this invention features an integrated design of beam expander-color separator-beam combiner, which combines the ability to flexibly switch between high energy density (0.1 mm spot size) and large effective area (5 mm spot size).

[0097] Example 5: Internal and external surface structures of the treatment handle of the present invention:

[0098] The treatment handpiece has a built-in treatment control module that integrates a skin impedance detection sensor, a pulse energy closed-loop feedback unit, and a multi-wavelength collaborative triggering circuit, supporting dual-wavelength independent or alternating output modes.

[0099] The treatment control module also includes a pulse sequence generation unit and a lesion identification unit;

[0100] The pulse sequence generation unit supports 1064 nm single-wavelength mode, 532 nm single-wavelength mode, and dual-wavelength mode.

[0101] Wavelength alternation mode, with an adjustable alternation frequency of 1-100 Hz;

[0102] The lesion identification unit automatically matches wavelength selection strategies based on multispectral imaging data, wherein:

[0103] The 1064 nm pulse is preferentially activated in melanin-targeting tissues.

[0104] 532 nm pulses are preferentially activated for hemoglobin-targeting tissues;

[0105] The dual-wavelength alternation mode is used for the treatment of complex lesions.

[0106] The invention provides a safety protection unit on the outer surface of the treatment handle, comprising a contact cooling window, a real-time skin temperature monitoring probe, and an automatic pulse over-limit cutoff device. The contact cooling window adopts a modular quick-release design and is electrically connected to the handle body via spring pin contacts. The cooling window has a diameter of 20 mm and a pressure adjustment range of 0.5-2 N / cm². The temperature monitoring probe is arranged in a ring array around the cooling window, containing 8 miniature infrared sensors with a sampling rate of 1 kHz and a spatial resolution of 50 μm.

[0107] Example 6: The structure of the light guide arm of the present invention:

[0108] The end joint of the light guide arm of this invention is equipped with a dynamic focusing scanning galvanometer and a field lens containing X / Y axis scanning lenses. The dynamic focusing scanning galvanometer includes a high-speed Galvo scanning head, an adaptive focusing lens group, and a spot shape control unit. The high-speed Galvo scanning head has a maximum scanning speed of ≥2 m / s; the adaptive focusing lens group has a focal length adjustment range of 10-150 mm and a response time of <5 ms; and the spot shape control unit supports dynamic switching between circular, square, and linear spot shapes.

[0109] The field lens is an F-θ field lens, a telecentric field lens, or a 3D field lens, with a focal length of 30-500mm.

[0110] Each joint of the light guide arm has a built-in position encoder that provides real-time feedback on angle deviations to the control system. The galvanometer compensates for optical path offsets using an adaptive PID algorithm.

[0111] Example 7: Pulse Parameter Optimization Algorithm Module in the Control System of the Present Invention

[0112] The pulse parameter optimization algorithm module calculates the photothermal damage threshold in real time based on Monte Carlo simulation, and dynamically adjusts the combination of pulse energy and repetition frequency to ensure that the thermal relaxation time (TRT) is controlled within the range of 0.1-10 ms.

[0113] Example 8: Experimental verification data of the whole machine of the dual-wavelength picosecond ultrafast laser skin treatment device of the present invention:

[0114] Spectral characteristics of the therapeutic mode-locked picosecond laser ultrashort pulse output from the center of the treatment handpiece: 1064 nm linewidth <0.1 nm, 532 nm linewidth <0.05 nm (measured by a grating spectrometer).

[0115] Long-term stability: After 8 hours of continuous operation, the power fluctuation is <±1.5% (PID control pump current).

[0116] The average pulse width is 1-15 ps, the energy difference between pulses at the same transmission frequency is ≤±2%, the peak power of a single pulse is 0.4-240.0 megawatts, and the peak power difference between pulses is ≤±3%.

[0117] The ultrafast laser skin treatment device of this invention achieves stable dual-wavelength output (power fluctuation <1.5%) through SESAM self-stabilized mode-locking regenerative amplification and LBO crystal cascade frequency doubling, adapting to the multi-level needs of skin treatment.

[0118] The above embodiments are only used to illustrate the technical solutions of the present invention and not to limit it. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art can still make modifications or equivalent substitutions to the specific implementation of the present invention. Any modifications or equivalent substitutions that do not depart from the spirit and scope of the present invention are within the protection scope of the claims of the present invention pending approval.

Claims

1. A dual-wavelength picosecond ultrafast laser skin treatment device, the device comprising a main unit (1) and a light guiding system (2), the main unit comprising a picosecond laser (4) and a control system (6), the light guiding system comprising a light guiding arm (8) and a treatment handle (9), the treatment handle (9) being disposed at the free end of the light guiding arm (8) and connected to the main unit (1) via the light guiding arm (8), characterized in that, The picosecond laser (4) is built into the host (1), and includes a SESAM passive mode-locked seed laser (10), a regenerative amplifier (11) and a beam transmission module; The SESAM passive mode-locked seed laser (10) uses a single-tube semiconductor laser (101) as the pump source and obtains a stable output of mode-locked picosecond laser through a resonant cavity arranged in a double Z-shape; the SESAM passive mode-locked seed laser (10) injects pump light with a power range of 1W-10W and outputs two mode-locked lights, each with a power range of 0.1W-4W; one of the mode-locked lights is selected to be 70MHz-120MHz, with a single pulse energy of 10-500nJ, which enters the regenerative amplifier for amplification; The regenerative amplifier (11) is a regenerative amplifier with a doubled resonant cavity. The mode-locked picosecond laser entering the regenerative amplifier is resonated and amplified once in the regenerative resonant amplification cavity, and then passes through the LD pump laser crystal module four times. The 1064nm fundamental frequency light output by the mode-locked picosecond laser through the regenerative amplifier is frequency doubled by the nonlinear crystal LBO, and simultaneously outputs dual wavelengths of 1064nm fundamental frequency light and 532nm frequency doubled light. The beam transmission module includes a beam expander system, a dichroic mirror group and a 532nm / 1064nm dual-band beam combiner, which realizes that the diameter of the dual-wavelength output beam spot is continuously adjustable from 0.01 to 5 mm. One end of the light guide arm (8) is connected to the output end of the dual-band beam combiner, and the other end is provided with a treatment handle (9). The dual-band beam combiner generates an output laser that is transmitted through the light guide arm (8) and then output through the center of the treatment handle (9). A dynamic focusing scanning galvanometer containing X / Y axis scanning lenses is installed in the end joint of the light guide arm (8).

2. The dual-wavelength picosecond ultrafast laser skin treatment device according to claim 1, characterized in that, The output light frequency amplified by the regenerative amplifier is 50kHz-800kHz, and the single pulse energy is adjustable from 10-300 microjoules; the incident light of the regenerative amplifier and the amplified output light form a 180° angle.

3. The dual-wavelength picosecond ultrafast laser skin treatment device according to claim 1, characterized in that, The treatment handpiece (9) outputs a treatment mode-locked picosecond laser ultrashort pulse with an average pulse width of 1-15 ps, an energy difference between pulses at the same emission frequency of ≤±2%, a peak power of 0.4-240.0 megawatts, and a peak power difference between pulses of ≤±3%.

4. The dual-wavelength picosecond ultrafast laser skin treatment device according to claim 1, characterized in that... , The dichroic mirror assembly comprises: a first dichroic mirror, which, at a 45° incident angle, exhibits high reflectivity (R>99.8%) at 1064 nm and high transmittance (T>95%) at 532 nm; and a second dichroic mirror, which, at a 45° incident angle, exhibits high reflectivity (R>99.5%) at 532 nm and high transmittance (T>95%) at 1064 nm. The energy ratio of the two wavelengths can be continuously adjusted within the range of 1:1 to 10:1 by rotating the angles of the first and second dichroic mirrors respectively.

5. The dual-wavelength picosecond ultrafast laser skin treatment device according to claim 1, characterized in that, The treatment handle (9) has a built-in treatment control module that integrates a skin impedance detection sensor, a pulse energy closed-loop feedback unit, and a multi-wavelength collaborative triggering circuit, supporting dual-wavelength independent or alternating output modes.

6. The dual-wavelength picosecond ultrafast laser skin treatment device according to claim 5, characterized in that, The treatment control module also includes a pulse sequence generation unit and a lesion identification unit; the pulse sequence generation unit supports a 1064 nm single-wavelength mode, a 532 nm single-wavelength mode, and a dual-wavelength alternating mode, with an alternation frequency adjustable from 1 to 100 Hz; the lesion identification unit automatically matches wavelength selection strategies based on multispectral imaging data, wherein: 1064 nm pulses are preferentially activated for melanin target tissues; 532 nm pulses are preferentially activated for hemoglobin target tissues; and the dual-wavelength alternating mode is used for the treatment of complex lesions.

7. The dual-wavelength picosecond ultrafast laser skin treatment device according to claim 1, characterized in that, The dynamic focusing scanning galvanometer includes a high-speed Galvo scanning head, an adaptive focusing lens group, and a spot shape control unit. The high-speed Galvo scanning head has a maximum scanning speed of ≥3m / s; the adaptive focusing lens group has a focal length adjustment range of 10-150mm and a response time of <5ms; and the spot shape control unit supports dynamic switching between circular, square, and linear spot shapes.

8. The dual-wavelength picosecond ultrafast laser skin treatment device according to any one of claims 1-7, characterized in that, The control system (6) includes a pulse parameter optimization algorithm module, which calculates the photothermal damage threshold in real time based on Monte Carlo simulation, dynamically adjusts the combination of pulse energy and repetition frequency, and ensures that the thermal relaxation time (TRT) is controlled within the range of 0.1-10 ms.

9. The dual-wavelength picosecond ultrafast laser skin treatment device according to claim 1, characterized in that, Each joint of the light guide arm (8) has a built-in position encoder that provides real-time feedback of angle deviation to the control system (6). The galvanometer compensates for optical path offset through an adaptive PID algorithm.

10. The dual-wavelength picosecond ultrafast laser skin treatment device according to claim 1, characterized in that, The outer surface of the treatment handle (9) is provided with a safety protection unit, which includes a contact cooling window, a real-time epidermal temperature monitoring probe and an automatic pulse over-limit cut-off device. The contact cooling window adopts a modular quick-release design and is electrically connected to the handle body through spring pin contacts. The cooling window has a diameter of 20 mm and a pressure adjustment range of 0.5-2 N / cm². The temperature monitoring probe is arranged in a ring array around the cooling window, containing 8 miniature infrared sensors with a sampling rate of 1 kHz and a spatial resolution of 50 μm.

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