A mid-infrared femtosecond laser hair growth device and therapeutic instrument

Abstract

This invention relates to a mid-infrared femtosecond laser hair regrowth device and treatment instrument. The mid-infrared femtosecond laser hair regrowth device includes a regenerative amplification module for generating near-infrared femtosecond laser; a parametric conversion module for receiving the near-infrared femtosecond laser, converting it into mid-infrared laser, and outputting it; an anti-resonant hollow fiber, the input end of which is coupled to receive the mid-infrared femtosecond laser output by the parametric conversion module for transmitting the mid-infrared laser; and a treatment handpiece including a first collimating lens, a scanning galvanometer, and a liquid lens. The first collimating lens is located on the output optical path of the anti-resonant hollow fiber for collimating the mid-infrared laser, the scanning galvanometer is used to control the deflection of the collimated beam, and the liquid lens is used to receive the deflected beam and adjust its focusing state. The mid-infrared femtosecond laser hair regrowth device and treatment instrument can output mid-infrared femtosecond laser with precise wavelength, achieve low-loss flexible laser transmission, and can be adjusted in real time on the working surface.

Description

Technical Field

[0001] This invention belongs to the field of laser technology, and in particular relates to a mid-infrared femtosecond laser hair growth device and treatment instrument. Background Technology

[0002] Hair loss has plagued over 250 million people in China, and laser hair regrowth has become the preferred clinical and home treatment option due to its non-invasive nature and lack of side effects. From a mechanism of action perspective, laser activation requires precise matching to the absorption characteristics of hair follicle stem cells. Hair follicles are located 2-3 mm below the epidermis, and their stem cells contain lipid components (such as ceramides) with a specific resonance absorption peak in the 5-8 μm mid-infrared band. Femtosecond lasers in this band can activate atrophied hair follicles through a dual mechanism of "characteristic absorption photothermal stimulation (precisely raising the hair follicle temperature to 37-40℃, activating hair follicle metabolism) and photobiological regulation (triggering the PI3K / Akt signaling pathway, promoting stem cell proliferation)." Simultaneously, the femtosecond pulse (<300 fs) effectively reduces thermal damage to the tissue because it is shorter than the tissue thermal relaxation time (approximately 1 ms).

[0003] However, current mainstream technologies remain in the visible and near-infrared bands, which have poor band adaptability and limited hair regrowth effects. For example, 630-900nm low-energy laser (LLLT) devices have an effectiveness rate of less than 35% for androgenetic alopecia, and require daily use for 20 minutes for 6 consecutive months to show results; 1550nm near-infrared non-ablative fractional lasers, although penetrating to a depth of 2mm, lack follicle-specific absorption peaks in this band, requiring indirect stimulation of hair follicles through thermal coagulation, which easily leads to scalp crusting (occurrence rate 15%), and the recovery period after a single treatment can be as long as 7 days; 10.6μm CO2 lasers penetrate to a depth of 3mm, but their wavelength is far from the tissue resonance peak. Due to strong water absorption, they are accompanied by significant thermal damage. As for the 5-8μm mid-infrared band, due to limited research, there are no mature hair regrowth devices yet. Only a few laboratories have verified their effectiveness using free-electron lasers, but their clinical application is limited by the size and cost of the equipment.

[0004] Furthermore, existing equipment transmission and scanning schemes have significant limitations, mainly due to rigid transmission schemes and insufficient operational flexibility. For example, existing mid-infrared / near-infrared laser equipment mostly uses light guide arms (containing multiple reflectors) to transmit the beam. Although energy transfer can be achieved, the rigid mechanical structure limits the turning angle and makes the operation relatively rigid.

[0005] At the same time, existing laser handpieces are difficult to use in both focused and large spot scanning modes, resulting in low flexibility in treatment parameters. Summary of the Invention

[0006] In view of this, the present invention provides a mid-infrared femtosecond laser hair regrowth device and treatment instrument, which solves the problems of poor band adaptability, rigid transmission scheme and insufficient flexibility of treatment parameters of existing equipment.

[0007] To achieve the above objectives, in a first aspect, the technical solution of the present invention to solve the technical problem is to provide a mid-infrared femtosecond laser hair generation device, comprising: a regenerative amplification module for generating near-infrared femtosecond laser; a parametric conversion module for receiving near-infrared femtosecond laser, converting it into mid-infrared laser, and outputting it; an anti-resonant hollow fiber, the input end of which is coupled to receive the mid-infrared femtosecond laser output by the parametric conversion module for transmitting the mid-infrared laser; and a treatment handpiece comprising a first collimating lens, a scanning galvanometer, and a liquid lens, wherein the first collimating lens is located on the output optical path of the anti-resonant hollow fiber for collimating the mid-infrared laser, the scanning galvanometer is used to control the deflection of the collimated beam, and the liquid lens is used to receive the deflected beam and adjust its focusing state.

[0008] In one specific embodiment, the regenerative amplification module includes a seed source, a pulse stretcher, a regenerative amplification cavity, a gain crystal, a first beam combiner, and a pump source. The seed source generates a seed pulse. The optical path input of the pulse stretcher receives the seed pulse and performs temporal stretching on it. The optical path input of the regenerative amplification cavity receives the stretched seed pulse. The gain crystal is located on the optical path within the regenerative amplification cavity. The pump source emits pump light. The first beam combiner guides the pump light into the gain crystal. The stretched seed pulse propagates back and forth within the regenerative amplification cavity and passes through the gain crystal multiple times to extract energy from the pump light for amplification.

[0009] In one specific embodiment, the regenerative amplification cavity includes a first polarization beamsplitter, a Faraday rotator, a second polarization beamsplitter, a Pockel cell, a quarter-wave plate, a first end-face mirror, a beam splitter, and a second end-face mirror; wherein, the second polarization beamsplitter, the Pockel cell, the quarter-wave plate, the first end-face mirror, the beam splitter, and the second end-face mirror form a resonant optical path, the gain crystal is located between the beam splitter and the second end-face mirror, and the first polarization beamsplitter and the Faraday rotator are used to separate and output the amplified laser pulse from the resonant optical path.

[0010] In one specific embodiment, the regenerative amplification module further includes a light-shielding baffle located in the optical path direction of the pump light after it is absorbed by the gain crystal and emitted, for absorbing and dissipating residual pump light that has not been absorbed by the gain crystal.

[0011] In one specific embodiment, a grating pair is provided between the regenerative amplification module and the parametric conversion module for pulse compression of the near-infrared femtosecond laser output by the regenerative amplification module.

[0012] In one specific embodiment, the parametric conversion module includes a polarization beam splitting adjustment unit, a YAG crystal, a pre-amplification crystal, a first filter, a second beam combiner, a main amplification crystal, and a second filter. The polarization beam splitting adjustment unit is used to split the near-infrared femtosecond laser output by the regenerative amplification module into a first beam and a second beam with independently adjustable power. The YAG crystal is disposed in the optical path of the first beam to receive the first beam and generate a supercontinuum. The pre-amplification crystal is disposed in the output optical path of the YAG crystal to receive the supercontinuum and perform pre-amplification. The first filter is disposed in the output optical path of the pre-amplification crystal to filter out the remaining pump light after pre-amplification. The second beam combiner is used to combine the beam after passing through the first filter with the second beam. The main amplification crystal receives the beam combined by the second beam combiner and converts and amplifies the beam energy to the mid-infrared band through an optical parametric amplification process. The second filter is disposed in the output optical path of the main amplification crystal to filter out the remaining unabsorbed pump light and output purified mid-infrared femtosecond laser.

[0013] In one specific embodiment, the polarization beam splitting adjustment unit includes a first half-wave plate, a third polarization beam splitter, a second half-wave plate, and a fourth polarization beam splitter. The first half-wave plate is located in the output optical path of the regenerative amplification module. The third polarization beam splitter is located in the output optical path of the first half-wave plate and is used to split the incident light into a first beam and a third beam. The second half-wave plate is located in the optical path of the third beam. The fourth polarization beam splitter is located in the output optical path of the second half-wave plate and is used to split the third beam into a second beam and a fourth beam. The parametric conversion module also includes a reflector and a third beam combiner. The third beam combiner is located between the YAG crystal and the pre-amplified crystal. The reflector is used to reflect the fourth beam to the third beam combiner. The third beam combiner is used to combine the fourth beam and the output beam of the YAG crystal.

[0014] In one specific embodiment, a second collimating lens and a focusing coupling lens are sequentially disposed between the output end of the parametric conversion module and the anti-resonant hollow fiber. The second collimating lens is used to collimate the mid-infrared femtosecond laser output by the parametric conversion module, and the focusing coupling lens is used to focus the collimated parallel laser beam to couple with the anti-resonant hollow fiber.

[0015] In one specific embodiment, the anti-resonant hollow optical fiber includes a central tube, peripheral tubes, and an outer cladding. The number of peripheral tubes is seven, and the seven peripheral tubes surround the central tube, with the line connecting their center points forming a regular hexagon. The outer cladding covers the side of the peripheral tubes away from the central tube.

[0016] Secondly, the present invention provides a therapeutic device, including a mid-infrared femtosecond laser hair regrowth device and a housing, wherein the mid-infrared femtosecond laser hair regrowth device is integrated into the housing.

[0017] Compared with the prior art, the mid-infrared femtosecond laser hair regrowth device and treatment instrument provided by the present invention have the following beneficial effects: By employing an integrated light source scheme based on regenerative amplification and optical parametric conversion, a mid-infrared femtosecond laser with a wavelength precisely covering the 6-9µm range was successfully output. This wavelength band highly matches the specific absorption peak of lipid components within hair follicle stem cells, thus solving the problems of poor targeting and high risk of thermal damage in existing visible / near-infrared laser devices, ensuring high efficiency and safety in treatment from the perspective of its mechanism of action. Secondly, chalcogenide glass antiresonant hollow fiber was selected as the core transmission medium for this mid-infrared band, replacing the traditional bulky and directionally restricted optical guide arm structure. This not only achieves efficient, low-loss, and flexible laser transmission but also greatly improves the operational flexibility of the treatment handpiece and the freedom of equipment layout. Finally, a two-dimensional scanning galvanometer and an electrically controlled liquid lens were integrated into the treatment handpiece, enabling rapid and precise scanning of the output spot position and real-time, stepless adjustment of its size on the working surface. This overcomes the limitations of existing devices with fixed treatment modes and inconvenient parameter adjustments, allowing for personalized and adaptive precise irradiation for different treatment areas and hair follicle conditions, comprehensively improving the treatment effect and efficiency. Attached Figure Description

[0018] Figure 1 This is a schematic diagram of the optical path structure of a mid-infrared femtosecond laser hair regrowth device provided in the first embodiment of the present invention; Figure 2 for Figure 1 Schematic diagram of the optical path structure of the regenerating amplification cavity; Figure 3 for Figure 1 A schematic diagram of the cross-sectional structure of a hollow-core optical fiber with anti-resonance; Figure 4 for Figure 1 Schematic diagram of the optical path structure of the treatment handpiece; Explanation of reference numerals in the attached figures: 1. Regeneration and amplification module; 2. Parametric conversion module; 3. Anti-resonant hollow fiber; 4. Treatment handpiece; 5. Grating pair; 6. Second collimating lens; 7. Focusing coupling lens; 11. Seed source; 12. Pulse stretcher; 13. Regeneration and amplification cavity; 14. Gain crystal; 15. First beam combiner; 16. Pump source; 17. Light-shielding baffle; 21. Polarization beam splitting adjustment unit; 22. YAG crystal; 23. Pre-amplification crystal; 24. First filter; 25. Second beam combiner; 26. Main amplification crystal; 27. Second filter; 28. Reflector ; 29. ​​Third beam combiner; 31. Central tube; 32. Outer tube; 33. Outer cladding; 41. First collimating mirror; 42. Scanning galvanometer; 43. Liquid lens; 131. First polarization beam splitter; 132. Faraday rotator; 133. Second polarization beam splitter; 134. Pockel cell; 135. Quarter-wave plate; 136. First end-face mirror; 137. Beam splitter; 138. Second end-face mirror; 211. First half-wave plate; 212. Third polarization beam splitter; 213. Second half-wave plate; 214. Fourth polarization beam splitter. Detailed Implementation

[0019] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of this application, and not all of the embodiments. Based on the embodiments of this application, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of this application.

[0020] It should be noted that all directional indications in the embodiments of this application are only used to explain the relative positional relationship and movement of each component in a specific posture. If the specific posture changes, the directional indications will also change accordingly.

[0021] Furthermore, the use of terms such as "first" and "second" in this application is for descriptive purposes only and should not be construed as indicating or implying their relative importance or implicitly specifying the number of technical features indicated. Therefore, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. Additionally, the technical solutions of the various embodiments can be combined with each other, but only on the basis of being achievable by those skilled in the art. When the combination of technical solutions is contradictory or impossible to implement, such a combination of technical solutions should be considered non-existent and not within the scope of protection claimed in this application.

[0022] like Figures 1 to 4 As shown, the first embodiment of this application provides a mid-infrared femtosecond laser hair regrowth device, which includes: Regeneration amplification module 1 is used to generate near-infrared femtosecond laser; Parametric conversion module 2 is used to receive near-infrared femtosecond laser, convert it into mid-infrared laser with a wavelength of 6 to 9 μm and output it; Anti-resonant hollow fiber 3, whose input end is coupled to receive the mid-infrared femtosecond laser output from parametric conversion module 2, is used to transmit mid-infrared laser; The treatment handpiece 4 includes a first collimating mirror 41, a scanning galvanometer 42, and a liquid lens 43. The first collimating mirror 41 is located on the output optical path of the anti-resonant hollow fiber 3 and is used to collimate the mid-infrared laser. The scanning galvanometer 42 is used to control the deflection of the collimated beam for two-dimensional scanning. The liquid lens 43 is used to receive the deflected beam and adjust its focusing state to form a treatment spot with adjustable position and size on the working surface.

[0023] Specifically, after the regeneration amplification module 1 generates a high-power near-infrared femtosecond laser, this laser enters the parametric conversion module 2 and is converted into a mid-infrared laser with a wavelength of 6-9 μm. This mid-infrared laser is then flexibly and with low loss transmitted through the anti-resonant hollow fiber 3. After being output from the anti-resonant hollow fiber 3, the mid-infrared laser is first collimated by the first collimating lens 41. The collimated beam is then incident on the scanning galvanometer 42, which is driven by a motor to rotate, thus deflecting the beam direction and enabling flexible movement of the beam on the treatment plane. The deflected beam then enters the liquid lens 43, which performs real-time, non-mechanical focus adjustment of the scanning beam, thereby dynamically forming a treatment spot on the working surface with flexibly controllable position and continuously adjustable size, achieving precise and adaptive irradiation of the scalp hair follicles.

[0024] In this embodiment, the first collimating lens 41 is a ZnSe aspherical lens with a focal length of 50mm (AR@6-9μm>95%), located 50mm from the exit of the anti-resonant hollow fiber 3, and the collimated spot size is approximately 3mm. The scanning galvanometer 42 consists of two orthogonally placed specially coated reflective lenses (HR@6-9μm>95%), each connected by a motor to control the rapid oscillation of the lens at any angle (<10 degrees), enabling flexible movement of the beam on the treatment plane.

[0025] In one embodiment, the regenerative amplification module 1 includes a seed source 11, a pulse stretcher 12, a regenerative amplification cavity 13, a gain crystal 14, a first beam combiner 15, and a pump source 16. The seed source 11 is used to generate a seed pulse. The optical path input of the pulse stretcher 12 receives the seed light pulse and is used to perform time-domain stretching of the seed pulse. The optical path input of the regenerative amplification cavity 13 receives the stretched seed pulse. The gain crystal 14 is located on the optical path within the regenerative amplification cavity 13. The pump source 16 is used to emit pump light. The first beam combiner 15 is used to guide the pump light into the gain crystal 14. The broadened seed pulse propagates back and forth within the regeneration amplification cavity 13 and passes through the gain crystal 14 multiple times to extract energy from the pump light and achieve amplification.

[0026] Specifically, after the seed source 11 outputs the seed pulse, it enters the pulse stretcher 12 for time-domain stretching, and then enters the regeneration amplification cavity 13. The pump light emitted by the pump source 16 is guided into the gain crystal 14 by the first beam combiner 15 to excite the gain crystal 14 to generate gain. The stretched seed pulse propagates back and forth in the regeneration amplification cavity 13, and each round trip is amplified by the gain crystal 14 until it is amplified to a specified size. Then, it is output from the regeneration amplification cavity 13 to the parametric conversion module 2.

[0027] In this embodiment, the seed source 11 generates a seed pulse with a center wavelength of 1030 nm and a pulse width of less than 250 fs. The pulse stretcher 12 is a Martinez stretcher, which stretches the pulse width of the seed pulse to 300 ps to reduce the peak power of the pulse and avoid damage to optical devices. The gain crystal 14 is a Yb:Galgo crystal, and the pump source 16 is a diode pump source.

[0028] In one embodiment, the regenerating amplification cavity 13 includes a first polarization beam splitter 131, a Faraday rotator 132, a second polarization beam splitter 133, a Pockels cell 134, a quarter-wave plate 135, a first end face mirror 136, a beam splitter 137, and a second end face mirror 138. The second polarization beam splitter 133, Pockel cell 134, quarter-wave plate 135, first end face mirror 136, beam splitter 137 and second end face mirror 138 form a resonant optical path. Gain crystal 14 is located between beam splitter 137 and second end face mirror 138. The first polarization beam splitter 131 and Faraday rotator 132 are used to separate and output the amplified laser pulse from the resonant optical path.

[0029] Specifically, the seed pulse is initially p-polarized and first incident on the first polarization beamsplitter 131. Since its p-polarization state matches the transmission polarization condition of the first polarization beamsplitter 131, the pulse is transmitted and enters the Faraday rotator 132. Under the influence of a preset magnetic field, the Faraday rotator 132 rotates its polarization direction by 45 degrees, forming a specific directional polarization state. The rotated pulse is then incident on the second polarization beamsplitter 133. The second polarization beamsplitter 133 exhibits high transmission characteristics for this directional polarization state pulse, allowing it to smoothly transmit into the resonant optical path composed of the second polarization beamsplitter 133, the Pockel cell 134, the quarter-wave plate 135, the first end-face mirror 136, the beam splitter 137, and the second end-face mirror 138.

[0030] After entering the resonant optical path, the pulse first enters the Pockel cell 134. At this time, the Pockel cell 134 is not driven by voltage and is in an unmodulated state, so the pulse polarization state is not changed. The pulse is directly incident on the quarter-wave plate 135. When the pulse passes through the quarter-wave plate 135 for the first time, the polarization state undergoes a 1 / 4-wave conversion (from the directional polarization state after Faraday rotation to s-polarization). Then, it is incident along the optical path to the first end-face reflector 136. The first end-face reflector 136 reflects the pulse perpendicularly according to the optical path design and returns to the quarter-wave plate 135 along the original path. When the pulse passes through the quarter-wave plate 135 for the second time, the polarization state undergoes another 1 / 4-wave conversion (from s-polarization back to the directional polarization state after rotation by the Faraday rotator 132). Then, it is incident along the optical path to the Pockel cell 134. The pulse passes through the unvoltaged Pockel cell 134, and the polarization state remains unchanged. It continues to return along the optical path to the second polarization beam splitter 133. At this time, the pulse polarization state matches the reflection condition of 133 and is directionally reflected by 133 to the beam splitter 137. Beam splitter 137 splits a small portion of the monitoring light (for real-time pulse power feedback), reflecting most of the main pulse along the optical path to gain crystal 14. As the pulse passes through gain crystal 14, it absorbs pump energy from pump source 16, achieving one energy amplification. The amplified pulse then travels along the optical path to second end-face reflector 138, which reflects the pulse back along its original path to second polarization beam splitter 133, thus completing one complete closed-loop cycle. This propagation process is repeated, with the pulse continuously circulating in the resonant optical path. Each time it passes through gain crystal 14, it absorbs pump energy, gradually accumulating and increasing power. The monitoring light from beam splitter 137 feeds back power data to the control system in real time, dynamically tracking whether a preset threshold has been reached.

[0031] When the pulse power is detected to meet the high power requirements of subsequent parametric conversion, a preset driving voltage is immediately applied to the Pockel cell 134, making the Pockel cell 134 equivalent to an additional quarter-wave plate and entering a polarization modulation state. The pulse in the loop passes through the modulated Pockel cell 134 again and is incident on the quarter-wave plate 135, where its polarization state undergoes a specific conversion (from the reflection-adapted polarization state of the loop phase to the transmission-adapted polarization state). After being reflected by the first end-face mirror 136, the pulse passes through the quarter-wave plate 135 and the Pockel cell 134 again (still in the modulation state), and its polarization state is further solidified into a state that can transmit through the second polarization beam splitter 133. It then transmits out from the second polarization beam splitter 133 and is incident on the Faraday rotator 132 along the optical path. The pulse passes through the Faraday rotator 132 a second time, and its polarization state is rotated again by 45° (a cumulative rotation of 90°, from the initial p-polarization to s-polarization), and then is incident on the first polarization beam splitter 131. At this point, the s-polarization state of the pulse does not match the transmission polarization condition of 131, and is reflected by the first polarization beam splitter 131, and is directionally transmitted to the subsequent parametric conversion module to complete the entire regeneration amplification process.

[0032] Understandably, the Faraday rotator 132 ensures that the output optical path and the input seed optical path are spatially separated in this process, achieving effective optical isolation and preventing backlight from damaging the preceding devices.

[0033] In one embodiment, the regenerative amplification module 1 further includes a light-shielding baffle 17 located in the direction of the light path after the pump light is absorbed by the gain crystal 14 and emitted. It is used to absorb and dissipate residual pump light that is not absorbed by the gain crystal 14, as well as stray light that leaks or is scattered from the regenerative amplification cavity 13. This prevents these stray lights from forming unnecessary reflections, scattering, or background interference inside the optical platform or equipment, ensuring a clean optical path for the system, improving the stability and signal-to-noise ratio of the laser output, and enhancing operational safety.

[0034] In one embodiment, a grating pair 5 is provided between the regeneration amplification module 1 and the parametric conversion module 2 for pulse compression of the near-infrared femtosecond laser output by the regeneration amplification module 1.

[0035] Specifically, after regeneration and amplification, the pulse energy has been significantly increased, but it is still stretched in time (on the picosecond scale). The function of the grating is to precisely compensate for the dispersion (mainly group velocity dispersion) introduced by the first-step stretcher, and to compress the amplified long pulse back into an ultrashort femtosecond pulse (restoring it to or close to the width of the seed pulse, such as <300 fs).

[0036] In one embodiment, the parametric conversion module 2 includes a polarization beam splitting adjustment unit 21, a YAG crystal 22, a pre-amplification crystal 23, a first filter 24, a second beam combiner 25, a main amplification crystal 26, and a second filter 27. The polarization beam splitting adjustment unit 21 is used to split the near-infrared femtosecond laser output from the regenerative amplification module 1 into a first beam and a second beam with independently adjustable power. YAG crystal 22 is disposed in the optical path of the first beam to receive the first beam and generate a supercontinuum spectrum; The pre-amplification crystal 23 is placed in the output optical path of the YAG crystal 22 to receive the supercontinuum and perform pre-amplification; The first filter 24 is disposed on the output light path of the pre-amplified crystal 23 to filter out the pump light remaining after pre-amplification; The second beam combiner 25 is used to combine the beam after passing through the first filter 24 with the second beam. The main amplifying crystal 26 receives the beam after it has been combined by the second beam combiner 25, and uses it to convert and amplify the beam energy to the mid-infrared band through an optical parametric amplification process. The second filter 27 is disposed in the output light path of the main amplifying crystal 26 to filter out the remaining pump light that has not been absorbed and output purified mid-infrared femtosecond laser.

[0037] Specifically, the high-power near-infrared femtosecond laser output from the regenerative amplification module 1, after being compressed by the grating pair 5, first enters the polarization beam splitting adjustment unit 21, where it is split into a first beam and a second beam with independently adjustable power. The first beam is guided and focused onto the YAG crystal 22, generating a supercontinuum covering the mid-infrared band through nonlinear effects, serving as the broadband signal source required for subsequent amplification. This supercontinuum, after passing through the pre-amplification crystal 23 and the first filter 24, is spatially combined with a portion of the second beam via the second beam combiner 25 and injected into the main amplification crystal 26. Inside the main amplification crystal, under phase-matching conditions, the pump light and signal light undergo a three-wave mixing nonlinear optical process, efficiently converting and amplifying the energy of the pump light to the mid-infrared band. Finally, the mixed beam emitted from the main amplification crystal 26, containing the mid-infrared target light and residual pump light, is filtered by the second filter 27 to remove the residual pump light, resulting in a purified, high-power mid-infrared femtosecond laser output.

[0038] In this embodiment, both the pre-amplification crystal 23 and the main amplification crystal 26 are LGS crystals. The LGS crystals have a cut angle of θ=90° and φ=51°, and the phase matching type is Type I. The first filter 24 and the second filter 27 are used to filter the 1030nm pump light.

[0039] In one embodiment, the polarization beam splitting adjustment unit 21 includes a first half-wave plate 211, a third polarization beam splitter 212, a second half-wave plate 213, and a fourth polarization beam splitter 214. The first half-wave plate 211 is located in the output optical path of the regeneration amplification module 1, the third polarization beam splitter 212 is located in the output optical path of the first half-wave plate 211, and is used to split the incident light into a first beam and a third beam. The second half-wave plate 213 is located in the optical path of the third beam, and the fourth polarization beam splitter 214 is located in the output optical path of the second half-wave plate 213, and is used to split the third beam into a second beam and a fourth beam. The parametric conversion module 2 also includes a reflector 28 and a third beam combiner 29. The third beam combiner 29 is located between the YAG crystal 22 and the pre-magnification crystal 23. The reflector 28 is used to reflect the fourth beam to the third beam combiner 29, and the third beam combiner 29 is used to combine the fourth beam and the output beam of the YAG crystal 22.

[0040] Specifically, the high-power near-infrared femtosecond laser output by the regenerating amplification module 1 is compressed by the grating pair 5, and first passes through the first half-wave plate 211 and enters the third polarization beam splitter 212. The third polarization beam splitter 212 splits it into a reflected first beam and a transmitted third beam. The first beam enters the YAG crystal 22 to generate a supercontinuum, and after being output from the YAG crystal 22, it enters the third beam combiner 29.

[0041] The third beam then enters the fourth polarization beam splitter 214 through the second half-wave plate 213. The fourth polarization beam splitter 214 splits the third beam into a transmitted second beam and a reflected fourth beam. The second beam is transmitted to the second beam combiner 25.

[0042] The fourth beam is reflected by mirror 28 to the third beam combiner 29, and after being combined with the YAG crystal 22 to form a supercontinuum beam, it enters the pre-amplification crystal 23. After being amplified by the pre-amplification crystal 23 and filtered by the first filter 24, it reaches the second beam combiner 25, and after being combined with the second beam, it enters the main amplification crystal 26.

[0043] In this embodiment, the power of the first beam is 2-3W, the power of the fourth beam is about 4W, the wavelength is 1030nm, and the length of the YAG crystal 22 is 10mm.

[0044] It is understood that there can be multiple reflectors 28, which are used to reflect the fourth beam to the third beam combiner 29, the second beam to the second beam combiner 25, and the output beam of the first filter 24 to the second beam combiner 25, respectively.

[0045] In one embodiment, a second collimating mirror 6 and a focusing coupling mirror 7 are sequentially arranged between the output end of the parametric conversion module 2 and the anti-resonant hollow fiber 3. The second collimating mirror 6 is used to collimate the mid-infrared femtosecond laser output by the parametric conversion module 2, and the focusing coupling mirror 7 is used to focus the collimated parallel laser beam to couple with the anti-resonant hollow fiber 3.

[0046] In this embodiment, the second collimating lens 6 is a zinc selenide lens with a focal length of 150mm. The mid-infrared femtosecond laser output by the parametric conversion module 2 has a divergence of about 15mrad. After being collimated by the second collimating lens 6, a collimated beam with a diameter of about 4mm can be obtained. The beam is then coupled into the anti-resonant hollow fiber 3 using the focusing coupling mirror 7.

[0047] In one embodiment, the anti-resonant hollow fiber 3 includes a central tube 31, an outer tube 32, and an outer cladding layer 33. There are seven outer tubes 32, which surround the central tube 31 and the line connecting their center points forms a regular hexagon. The outer cladding layer 33 covers the side of the outer tubes 32 away from the central tube 31.

[0048] Specifically, the central tube 31, the outer tube 32, and the outer cladding 33 together constitute the main structure of the anti-resonant hollow fiber. Both the central tube 31 and the outer tube 32 are made of As2S3 chalcogenide glass (refractive index n≈2.4). The inner diameter of the central tube 31 is 120μm and the wall thickness is 3.5μm. The two end faces of the anti-resonant hollow fiber 3 are polished (roughness ≤0.1μm, perpendicularity ≤0.5°) and coated with Ge / ZnSe multilayer antireflection coating. The input end face of the anti-resonant hollow fiber 3 is aligned with the output optical path of the focusing coupling mirror 7, and the output end face is seamlessly connected with the input optical path of the first collimating mirror 41 of the handpiece 4.

[0049] Understandably, the hollow structure of hollow optical fiber can suppress nonlinear effects during femtosecond laser transmission, while the chalcogenide glass substrate exhibits low intrinsic loss at 6-9μm. A tightly packed hexagonal structure of "1 central tube 31 + 7 peripheral tubes 32" is employed, using As2S3 chalcogenide glass (refractive index n≈2.4) with excellent light transmittance and anti-resonance compatibility, meeting the core requirements for mid-infrared light transmission.

[0050] In terms of end-face coating design, Ge / ZnSe multilayer antireflection coating technology is used at both ends of the optical fiber to effectively reduce end-face reflection loss, making the single end-face reflection loss ≤0.3dB, while improving end-face transmittance and environmental stability, and avoiding signal attenuation caused by end-face reflection. To ensure the coating effect, the end face needs to be polished to a roughness ≤0.1μm and a perpendicularity ≤0.5° to reduce the impact of coating defects on transmission performance.

[0051] The central tube 31 has an inner diameter of 120μm, effectively improving coupling efficiency and adapting to conventional 100 / 140μm core diameter mid-infrared fiber couplers. When the lateral alignment deviation is ≤±10μm and the angular alignment deviation is ≤±2°, a high coupling efficiency of ≥85% can still be maintained; with a precision alignment platform, the coupling efficiency can be further increased to over 90%. By precisely setting the wall thickness and structural dimensions, the fiber is matched to anti-resonance conditions: when the wall thickness is 3.5μm, 2nt=16.8μm, the m=2nd order resonant wavelength is 8.4μm (covering the 6-9μm mid-to-high end band), and the m=3rd order resonant wavelength is 5.6μm (close to the 6μm lower limit), achieving full coverage of the target band. During transmission, the fundamental mode (LP)... 01 Loss ≤0.8dB / m, while higher order modes (such as LP) 11 LP 21 With a loss ≥15dB / m, high-order modes are effectively suppressed through uniform arrangement of the outer tubes 32 and precise control of the wall thickness. The actual transmission is dominated by the fundamental mode, and the beam quality M²≤1.3.

[0052] In addition, the outer layer is coated with a 20-30μm thick polyimide coating, which improves mechanical strength and environmental adaptability. The bending radius is ≥5cm, which can cope with conventional installation and use scenarios. The key dimensional tolerances are strictly controlled (inner diameter ±1μm, wall thickness ±0.2μm, etc.) to ensure stable anti-resonance characteristics and avoid loss peak shift due to processing deviations.

[0053] In one embodiment, the liquid lens 43 includes a sealed cavity, a conductive liquid, an insulating liquid, two transparent electrodes, and two zinc selenide substrate lenses. The two zinc selenide substrate lenses are respectively sealed and attached to the openings at both ends of the sealed cavity, and the side of the lenses facing the cavity is coated with a transparent conductive film to form a transparent electrode. The sealed cavity is filled with immiscible conductive liquid and insulating liquid, which form a stable liquid-liquid interface inside the cavity. The transparent electrodes are connected to conductive leads extending outside the cavity to receive voltage signals to adjust the radius of curvature of the liquid-liquid interface, thereby achieving continuous adjustment of the focusing focal length to meet the spot size adjustment requirements of 6-9μm mid-infrared lasers.

[0054] Specifically, to correct the consistency and size of the light spot on the treatment plane, the liquid lens 43 adopts a PZT ceramic driven liquid lens, which consists of PZT voltage drive (0-150VDC, response time <1ms), ring PZT ceramic, and filling liquid (perfluoropolyether insulating liquid, such as perfluoroheptane (n-C7F16), FC-75, perfluorooctane, etc.). Specifically, the PZT-driven liquid lens is a cylindrical electrowetting structure with the following positional relationship: the entire structure is based on a cylindrical ZnSe shell (approximately 15mm outer diameter and 8mm length), with 2mm thick light-transmitting windows (inlet / outlet light surfaces) at both ends, and the inner wall of the shell is insulated; the shell encapsulates a dual-liquid system occupying 90% of its volume (with reserved deformation space), the lower layer is a highly transparent ion-conductive liquid connected to the substrate electrode, and the upper layer is a perfluoropolyether insulating liquid, which forms the core optical interface; two annular PZT ceramics (8mm inner diameter, 12mm outer diameter, and 1mm thickness) are symmetrically attached to the outer wall of the middle part of the shell, and the bonding surface is coated with thermally and electrically conductive adhesive. The inner wall of the shell is plated with an annular transparent electrode corresponding to the PZT position. This electrode is electrically connected to the PZT and only contacts the upper insulating liquid, forming a closed driving loop of "PZT-transparent electrode-conductive liquid". The PZT does not directly contact the liquid, but only transmits deformation to the dual-liquid interface through the shell.

[0055] The distance from the liquid lens 43 to the working plane is 100mm. On the working plane, the light spot is adjusted from the focal point to the 8mm tuning core by changing the focal length of the liquid lens driven by the PZT ceramic: In the initial state, the PZT ceramic has no driving voltage, and the lower conductive liquid and the upper insulating liquid inside the liquid lens 43 form a planar interface, with the lens focal length at its maximum value. To achieve focal spot tuning, the entire "voltage-focal length-focal spot size" calibration must be completed in advance to obtain the lens focal length and PZT driving voltage data corresponding to different focal spot sizes (e.g., an 8mm focal spot at a 100mm working distance requires a 60mm lens focal length; this data has been pre-calibrated and stored in the driving system). By controlling the driving voltage, the PZT ceramic undergoes radial contraction deformation due to the piezoelectric effect. This deformation is transmitted to the inner sidewall through the tightly fitted ZnSe shell, causing a uniform concavity in the sidewall and applying lateral pressure to the upper insulating liquid. Since the two liquids are immiscible and have fixed surface tension, the pressure forces the liquid interface to bend. The lens is convex (the degree of curvature is precisely controlled by the pre-calibrated voltage), and the focal length of the lens gradually decreases from 100mm to 60mm. According to the Gaussian optical formula D2=D1×(Lf) / f (D1=3mm, L=100mm, f=60mm), the focal spot size increases synchronously as the focal length decreases. When the focal length is precisely reduced to 60mm, the focal spot at 100mm expands to exactly 8mm. The entire process relies on the precise data of pre-calibration to ensure tuning accuracy. Combined with the environmental isolation measures of constant temperature chamber and shock absorption frame, as well as the fast response characteristics of PZT≤1ms, it can be adapted to the characteristics of femtosecond lasers and achieve stable tuning.

[0056] The second embodiment of the present invention provides a therapeutic device, which includes a mid-infrared femtosecond laser hair growth device and a housing, wherein the mid-infrared femtosecond laser hair growth device is integrated into the housing.

[0057] Understandably, the treatment device integrates the mid-infrared femtosecond laser hair regrowth device as its core functional module into a unified housing, forming a complete integrated medical device. The housing not only provides mechanical support, physical protection, and electromagnetic shielding for the internal precision optical and electronic modules, but also typically integrates a power management system, overall control circuitry, heat dissipation unit, and safety interlocking mechanism, enabling the hair regrowth device to operate stably, reliably, and safely.

[0058] Compared with existing technologies, the mid-infrared femtosecond laser hair regrowth device and treatment instrument provided by this invention successfully outputs mid-infrared femtosecond laser with a wavelength precisely covering the 6-9µm range through an integrated light source scheme based on regenerative amplification and optical parametric conversion. This wavelength band highly matches the specific absorption peak of lipid components in hair follicle stem cells, thus solving the problems of poor targeting and high risk of thermal damage in existing visible / near-infrared laser devices, ensuring high efficiency and safety of treatment from the perspective of the mechanism of action. Secondly, the use of chalcogenide glass antiresonant hollow fiber as the core transmission medium in this mid-infrared band replaces the traditional bulky and directionally restricted optical guide arm structure, which not only achieves efficient, low-loss, and flexible laser transmission, but also greatly improves the operational flexibility of the treatment handpiece and the freedom of equipment layout. Finally, the treatment handpiece integrates a two-dimensional scanning galvanometer and an electrically controlled liquid lens, enabling the output light spot to achieve rapid and precise scanning of position and real-time, stepless adjustment of size on the working surface. This overcomes the limitations of existing equipment, such as fixed treatment modes and inconvenient parameter adjustments, and allows for personalized and adaptive precise irradiation for different treatment areas and hair follicle conditions, comprehensively improving the treatment effect and efficiency.

[0059] The specific embodiments of the present invention described above do not constitute a limitation on the scope of protection of the present invention. Any other corresponding changes and modifications made in accordance with the technical concept of the present invention should be included within the scope of protection of the claims of the present invention.

Claims

1. A mid-infrared femtosecond laser hair regrowth device, characterized in that, include: Regenerative amplification module for generating near-infrared femtosecond lasers; The parametric conversion module is used to receive near-infrared femtosecond laser light, convert it into mid-infrared laser light, and output it. An anti-resonant hollow fiber is used to receive mid-infrared femtosecond laser output from the parametric conversion module at its input end for transmitting mid-infrared laser light. The treatment handpiece includes a first collimating mirror, a scanning galvanometer, and a liquid lens. The first collimating mirror is located on the output optical path of the anti-resonant hollow fiber and is used to collimate the mid-infrared laser. The scanning galvanometer is used to control the deflection of the collimated beam. The liquid lens is used to receive the deflected beam and adjust its focusing state.

2. The mid-infrared femtosecond laser hair regrowth device as described in claim 1, characterized in that: The regenerative amplification module includes a seed source, a pulse stretcher, a regenerative amplification cavity, a gain crystal, a first beam combiner, and a pump source. The seed source is used to generate a seed pulse. The optical path input of the pulse stretcher receives the seed pulse and is used to stretch the seed pulse in the time domain. The optical path input of the regenerative amplification cavity receives the stretched seed pulse. The gain crystal is located on the optical path within the regenerative amplification cavity. The pump source is used to emit pump light. The first beam combiner is used to guide the pump light into the gain crystal. The broadened seed pulse propagates back and forth within the regeneration amplification cavity and passes through the gain crystal multiple times to extract energy from the pump light for amplification.

3. The mid-infrared femtosecond laser hair regrowth device as described in claim 2, characterized in that: The regenerating amplification cavity includes a first polarization beam splitter, a Faraday rotator, a second polarization beam splitter, a Pockels cell, a quarter-wave plate, a first end-face mirror, a beam splitter, and a second end-face mirror. The second polarization beam splitter, the Pockel cell, the quarter-wave plate, the first end-face mirror, the beam splitter, and the second end-face mirror form a resonant optical path. The gain crystal is located between the beam splitter and the second end-face mirror. The first polarization beam splitter and the Faraday rotator are used to separate and output the amplified laser pulse from the resonant optical path.

4. The mid-infrared femtosecond laser hair regrowth device as described in claim 2, characterized in that: The regenerative amplification module also includes a light-shielding baffle located in the direction of the light path after the pump light is absorbed by the gain crystal and emitted, which is used to absorb and dissipate the residual pump light that is not absorbed by the gain crystal.

5. The mid-infrared femtosecond laser hair regrowth device as described in claim 1, characterized in that: A grating pair is provided between the regenerative amplification module and the parametric conversion module for pulse compression of the near-infrared femtosecond laser output by the regenerative amplification module.

6. The mid-infrared femtosecond laser hair regrowth device as described in claim 1, characterized in that: The parametric conversion module includes a polarization beam splitting adjustment unit, a YAG crystal, a pre-amplification crystal, a first filter, a second beam combiner, a main amplification crystal, and a second filter. The polarization beam splitting adjustment unit is used to split the near-infrared femtosecond laser output by the regenerative amplification module into a first beam and a second beam with independently adjustable power. The YAG crystal is disposed in the optical path of the first beam to receive the first beam and generate a supercontinuum spectrum. The pre-amplification crystal is disposed in the output optical path of the YAG crystal and is used to receive the supercontinuum and pre-amplify it; The first filter is disposed in the output light path of the pre-amplified crystal to filter out the pump light remaining after pre-amplification; The second beam combiner is used to combine the light beam after passing through the first filter with the second light beam; The main amplifying crystal receives the beam of light after it has been combined by the second beam combiner, and uses it to convert and amplify the beam energy to the mid-infrared band through an optical parametric amplification process. The second filter is disposed in the output light path of the main amplifying crystal to filter out the remaining pump light that has not been absorbed and output purified mid-infrared femtosecond laser.

7. The mid-infrared femtosecond laser hair regrowth device as described in claim 6, characterized in that: The polarization beam splitting adjustment unit includes a first half-wave plate, a third polarization beam splitter, a second half-wave plate, and a fourth polarization beam splitter. The first half-wave plate is located in the output optical path of the regenerative amplification module. The third polarization beam splitter is located in the output optical path of the first half-wave plate and is used to split the incident light into the first beam and the third beam. The second half-wave plate is located in the optical path of the third beam. The fourth polarization beam splitter is located in the output optical path of the second half-wave plate and is used to split the third beam into the second beam and the fourth beam. The parametric conversion module further includes a reflector and a third beam combiner. The third beam combiner is located between the YAG crystal and the pre-magnification crystal. The reflector is used to reflect the fourth beam to the third beam combiner, and the third beam combiner is used to combine the fourth beam and the output beam of the YAG crystal.

8. The mid-infrared femtosecond laser hair regrowth device as described in claim 1, characterized in that: A second collimating lens and a focusing coupling lens are sequentially arranged between the output end of the parametric conversion module and the anti-resonant hollow fiber. The second collimating lens is used to collimate the mid-infrared femtosecond laser output by the parametric conversion module, and the focusing coupling lens is used to focus the collimated parallel laser beam to couple with the anti-resonant hollow fiber.

9. The mid-infrared femtosecond laser hair regrowth device as described in claim 1, characterized in that: The anti-resonant hollow fiber includes a central tube, peripheral tubes, and an outer cladding. There are seven peripheral tubes, which surround the central tube and the line connecting their centers forms a regular hexagon. The outer cladding covers the side of the peripheral tubes away from the central tube.

10. A therapeutic device, characterized in that, The invention includes the mid-infrared femtosecond laser hair regrowth device and housing as described in any one of claims 1-9, wherein the mid-infrared femtosecond laser hair regrowth device is integrated within the housing.

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