Tunable laser for plaque ablation and plaque ablation system
By designing a tunable laser and combining photochemical reaction and nonlinear optical frequency conversion technology, the laser band switching of different patch components can be realized, which solves the problem that existing lasers cannot be tunable and improves the efficiency and effect of patch erosion.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- HORIMED TECH CO LTD
- Filing Date
- 2022-08-12
- Publication Date
- 2026-05-29
AI Technical Summary
Existing plaque ablation lasers are mostly single-frequency output, which cannot be tuned and cannot be adapted to the characteristics of different plaque components, resulting in low ablation efficiency.
A tunable laser was designed, combining laser photochemical reaction, photothermal effect and nonlinear optical frequency conversion technology. Through a primary frequency doubling unit and a tunable laser conversion unit, the laser band switching of different patch components can be realized. The tunable laser is formed by using a resonant cavity and a nonlinear crystal.
It improved the clinical efficacy of plaque ablation, enhanced the ability to eliminate different plaque components, reduced thermal damage to surrounding tissues, and improved ablation efficiency.
Smart Images
Figure CN115189215B_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of plaque removal technology, and more particularly to a tunable laser and plaque removal system for plaque removal. Background Technology
[0002] High-energy pulsed lasers transmitted via fiber optics are widely used for the ablation of biological tissues. In this ablation process, ultraviolet light energy is absorbed by biological tissues and organic compounds, rather than burning or cutting the tissue. Furthermore, ultraviolet lasers possess sufficient energy to break the molecular bonds of the tissue, effectively decomposing it in a tightly controlled manner through ablation. The intense absorption of laser energy causes a rapid increase in local temperature and generates powerful mechanical forces, resulting in photoacoustic and photothermal ablation. Therefore, ultraviolet lasers are suitable for eliminating plaque-like tissues, removing fine layers from the tissue surface without damaging surrounding tissues.
[0003] Chromophores in biological tissues can absorb photon energy, thereby undergoing photochemical reactions that lead to tissue dissociation. Different chromophores correspond to different absorption wavelengths, so tunable lasers play an important role in improving ablation efficiency and ablation effects.
[0004] Tunable solid-state lasers can maintain nanosecond-level pulse widths and high peak power while achieving wavelength tuning, which helps reduce thermal damage to surrounding tissues and enhances the ability to eliminate calcified plaques. In recent years, the development of ultraviolet optical fibers and advancements in coupling methods have greatly facilitated the transmission of high-energy tunable solid-state lasers in optical fibers. However, most existing plaque ablation lasers are single-frequency output lasers without tuning capabilities, and existing tunable lasers, due to differences in application fields and significant variations in resonant cavity structures, are unsuitable for plaque ablation work. Therefore, this study investigates a tunable laser for plaque ablation. Summary of the Invention
[0005] Therefore, the purpose of this invention is to provide a tunable laser for plaque ablation, which can take advantage of the different absorption spectra of different plaque components and the different photon energies of different wavelengths of laser. By combining laser photochemical reaction, photothermal effect and nonlinear optical frequency conversion technology, a new type of tunable laser has been developed. Different laser bands can be switched according to different plaque components, which further improves the clinical effect.
[0006] To achieve the above objectives, the present invention provides a tunable laser for patch ablation, comprising a primary frequency doubling unit and a tunable laser conversion unit.
[0007] The primary frequency doubling unit is used to perform primary frequency doubling on the original laser emitted by the pump source;
[0008] The tunable laser conversion unit utilizes the laser after initial frequency doubling to form laser oscillation in the resonant cavity, and obtains the final output tunable laser through frequency doubling and frequency reduction.
[0009] More preferably, the tunable laser conversion unit includes a second beam splitter, a second collimating component, a tunable module, a third collimating component, a third frequency-doubled crystal, a second sum-frequency crystal, and a tunable output reflector; the second beam splitter transmits the frequency-doubled laser formed after the pump source has undergone initial frequency doubling, the tunable module uses the frequency-doubled laser to form laser oscillation, the third collimating component focuses the laser oscillation onto the third frequency-doubled crystal, and the laser, after being frequency-doubled again, is sum-frequency-doubled and then used by the tunable output reflector to obtain the final output tunable laser.
[0010] More preferably, the resonant cavity in the tunable laser conversion unit includes two plane mirrors and a nonlinear crystal disposed between the plane mirrors. The nonlinear crystal is a BBO crystal used to generate 750-1050 nm signal light, and its two ends are coated with 532 nm and 750-1050 nm anti-reflection protective films.
[0011] More preferably, the resonant cavity in the tunable laser conversion unit consists of two plane mirrors and a laser crystal disposed between the plane mirrors. The laser crystal is irradiated with laser light, causing it to transition and generate an excitation laser that oscillates between the two plane mirrors.
[0012] More preferably, the laser crystal is a titanium sapphire crystal used to generate a 750-1050 nm tunable laser; the laser crystal is placed at Brewster angle relative to the pump laser on a copper heat sink controlled by a semiconductor cooler, the temperature of the semiconductor cooler is set to 17 degrees Celsius, and both ends are coated with 532 nm and 750-1050 nm anti-reflection protective films.
[0013] More preferably, the resonant cavity further includes a prism disposed between two plane mirrors, the prism being used to limit the starting wavelength.
[0014] Further preferably, it also includes a multi-channel single-frequency laser conversion unit, which is used to perform secondary frequency doubling or summing of the laser after the initial frequency doubling to output multiple single-frequency lasers of different bands.
[0015] More preferably, each of the multiple single-frequency laser conversion units includes a first beam splitter, a first collimation component, a first frequency doubling or summing crystal, and a single-frequency output reflector arranged along the same optical axis. The frequency doubling or summing crystal is coated with anti-reflection protective films of different wavelengths at both ends of the crystal, depending on the output wavelength.
[0016] More preferably, the single-frequency laser conversion unit includes a beam splitter, a collimation component, a second frequency-doubling crystal, and a single-frequency output mirror. The two ends of the second frequency-doubling crystal are coated with anti-reflection protective films of different wavelengths. After the laser is initially frequency-doubled by the beam splitter and the collimation component, the 532nm laser after the initial frequency doubling is frequency-doubled again by the second frequency-doubling crystal to output a single-frequency laser with a wavelength of 266nm.
[0017] More preferably, the single-frequency laser conversion unit includes a beam splitter, a collimation component, a second sum-frequency crystal, and a single-frequency output mirror. After the laser is initially frequency-doubled by the beam splitter and collimation component, it is frequency-summed using the second sum-frequency crystal. The second sum-frequency crystal is coated with anti-reflection protective films of different wavelengths at both ends, and outputs a single-frequency laser with a wavelength of 355nm.
[0018] More preferably, the system also includes a homogenization unit for homogenizing the output laser spot, and the homogenized spot is used to erode plaques in the blood vessels.
[0019] More preferably, the homogenization unit includes a beam homogenizer, a first homogenizing convex lens, a first multimode fiber, a second homogenizing convex lens, and a second multimode fiber;
[0020] The beam homogenizer is used to homogenize the beam spot of the output single-frequency laser or tunable laser. The first homogenizing convex lens is used to focus the homogenized beam spot onto the core of the first multimode fiber for output. The second homogenizing convex lens refocuses the output laser and couples it to the second multimode fiber. The laser that can finally ablate the spot is then output using the second multimode fiber.
[0021] The present invention also provides a patch removal system, which includes the above-mentioned tunable laser, a patch recognition module, and a removal module;
[0022] The plaque recognition module is used to identify the composition of the plaques;
[0023] The tunable laser is used to adjust the wavelength and energy of the emitted laser according to the identified patch composition.
[0024] The ablation module is used to receive tunable lasers of the corresponding wavelength band and perform precise ablation treatment on the lesion tissue according to the laser energy of the corresponding wavelength band.
[0025] More preferably, the patch recognition module adjusts the wavelength of the emitted laser according to the recognized patch type using the following method:
[0026] When the plaque is a calcified plaque, adjust the output of the tunable laser module to 355 nm laser.
[0027] When the plaque is a lipid plaque, adjust the output of the tunable laser module to 266nm laser.
[0028] When the patch is a fibrous patch or a mixed-component patch, the output of the tunable laser module is adjusted to a first tunable laser or a second tunable band laser; the first tunable laser is a 250-350 nm laser; the second tunable band laser is a 265-350 nm laser.
[0029] The tunable laser and patch ablation system disclosed in this application have at least the following advantages compared to the prior art:
[0030] 1. Taking advantage of the different absorption spectra of different plaque components, the photothermal effect of laser is combined with nonlinear optical frequency conversion technology. A resonant cavity is used to form a tunable laser. Different laser bands can be selected according to different plaque components, which further improves the clinical effect.
[0031] 2. The resonant cavity can generate laser oscillation through various means such as the transition characteristics of the laser crystal or the use of antireflection coatings of nonlinear crystals, which improves the versatility of laser applications. Furthermore, by using prisms to limit the starting wavelength, the laser band can be selected, thereby improving the erosion efficiency and effect.
[0032] 3. The tunable laser of this application can achieve the purpose of ablation for different lesions using a single type of conduit, without the need to change the conduit midway, thus improving the ablation efficiency. Attached Figure Description
[0033] Figure 1 This is a schematic diagram of the tunable laser for plaque removal according to the present invention.
[0034] Figure 2 This is a structural diagram of an adjustable resonator in one embodiment of the present invention.
[0035] Figure 3 This is a structural diagram of an adjustable resonator in another embodiment of the present invention.
[0036] Figure 4 This is a structural diagram of an adjustable resonator in another embodiment of the present invention.
[0037] Figure 5 This is a schematic diagram of the homogenization unit structure in the tunable laser of the present invention.
[0038] Figure 6 This is a structural diagram of a plaque removal system.
[0039] In the picture:
[0040] 1. Pump source; 2. Single-frequency output mirror; 3. Tunable output mirror; B1. First frequency-doubled crystal; 4. Beam splitter; B2. Second frequency-doubled crystal; B3. Third frequency-doubled crystal; H1. First sum-frequency crystal; H2. Second sum-frequency crystal; ZH. Collimation component; 13. First plane mirror; 14. Nonlinear crystal; 15. Second plane mirror; M. Prism. Detailed Implementation
[0041] The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.
[0042] As shown in Figure 1, one embodiment of the present invention provides a tunable laser for patch erosion, which includes a primary frequency doubling unit and a tunable laser conversion unit.
[0043] The primary frequency doubling unit is used to perform primary frequency doubling on the original laser emitted by the pump source;
[0044] The tunable laser conversion unit utilizes the laser oscillation generated in the resonant cavity after initial frequency doubling to obtain the final output tunable laser for plaque ablation through frequency doubling and re-frequency conversion. A in the figure represents the resonant cavity.
[0045] Based on a high-energy 1064 nm pulsed laser, high-energy 266 nm, 355 nm, and 250-350 nm tunable laser outputs are achieved by combining various nonlinear frequency conversion techniques with tunable laser technology. When the primary frequency doubling unit is working, pump source 1 emits pump light, which is collimated and focused into the first frequency doubling crystal B1 by collimation component ZH.
[0046] like Figure 2-3 As shown, it also includes at least one branch of a single-frequency laser conversion unit, which is used to perform secondary frequency doubling or summing of the laser after the initial frequency doubling to output multiple single-frequency lasers of different bands.
[0047] Each single-frequency laser conversion unit in the multi-channel single-frequency laser conversion unit includes a beam splitter, a collimation component, a frequency doubling or summing crystal, and a single-frequency output mirror arranged along the same optical axis. Depending on the output wavelength, the frequency doubling or summing crystal has anti-reflection protective films of different wavelengths coated at both ends of the crystal.
[0048] In one embodiment of this application, the single-frequency laser conversion unit has two paths: one outputting 266nm laser and the other outputting 355nm laser. Specifically, the 532nm laser, after being frequency-doubled by the frequency-doubling crystal B1, passes through three beam splitters 4 and is transmitted to one tunable laser conversion unit, one single-frequency laser conversion unit outputting 266nm laser, and one single-frequency laser conversion unit outputting 355nm laser, respectively.
[0049] In the single-frequency laser conversion unit that outputs 266nm laser light, the 532nm laser light is focused into the second frequency-doubled crystal B2 after being collimated by the collimation component, and the resulting 266nm frequency-doubled light is transmitted and output through the single-frequency output reflector 2.
[0050] In the single-frequency laser conversion unit that outputs 355nm laser light, the 532nm laser light is focused into the second sum-frequency crystal H2 after being collimated by the collimation component ZH, and then sums with the remaining 1064nm light to produce 355nm light. The 355nm sum-frequency light is transmitted and output through the single-frequency output reflector 2.
[0051] like Figure 2 As shown, in one embodiment of this application, the resonant cavity in the tunable laser conversion unit includes two plane mirrors, a first plane mirror 13 and a second plane mirror 15, and a nonlinear crystal 14 disposed between the plane mirrors. The nonlinear crystal is a BBO crystal used to generate 750-1050 nm signal light, and its two ends are coated with 532 nm and 750-1050 nm anti-reflection protective films.
[0052] In this embodiment, the 532 nm frequency-doubled light is focused onto the nonlinear crystal 14 by the collimating component ZH. The nonlinear crystal 14 forms an optical parametric oscillation in the resonant cavity composed of the first plane mirror 13 and the second plane mirror 15. The remaining 532 nm frequency-doubled light is reflected and output by the beam splitter 4. The 750-1050 nm signal light is focused onto the third frequency-doubled crystal B3 by the collimating component ZH to generate 375-525 nm frequency-doubled light. The 375-525 nm frequency-doubled light and the 750-1050 nm signal light are passed through the first sum-frequency crystal H1 to generate 250-350 nm sum-frequency light. The 250-350 nm sum-frequency light is transmitted and output through the tunable output reflector 3.
[0053] The first frequency doubling crystal B1 is an LBO crystal used to double the frequency of 1064 nm to 532 nm, and its front and back surfaces are coated with antireflection films of 1064 nm and 532 nm.
[0054] The second frequency doubling crystal B2 is a BBO crystal used to double the frequency of 532 nm to 266 nm, and both ends are coated with anti-reflection protective films of 532 nm and 266 nm.
[0055] The nonlinear crystal 14 is a BBO crystal used to generate 750-1050 nm signal light, with 532 nm and 750-1050 nm anti-reflection protective films coated at both ends.
[0056] The third frequency doubling crystal B3 is a BBO crystal used to double the frequency of 750-1050 nm signal light to 375-525 nm. Both ends are coated with anti-reflection protective films of 750-1050 nm and 375-525 nm.
[0057] The first sum-frequency crystal H1 is a BBO crystal, used to sum and frequency 750-1050 nm and 375-525 nm to generate 250-350 nm. Both ends are coated with anti-reflection protective films of 750-1050 nm, 375-525 nm and 250-350 nm.
[0058] The second sum-frequency crystal H2 is an LBO crystal used to sum and frequency 532 nm and 1064 nm to generate 355 nm. Both ends are coated with anti-reflection protective films of 532 nm, 1064 nm and 355 nm.
[0059] like Figure 3 As shown, in another embodiment of the present invention, unlike the embodiments described above, the primary frequency doubling unit includes a second sum-frequency crystal H2, which is positioned after the first frequency doubling crystal B1 and before the beam splitter 5. The first sum-frequency crystal is used to sum the frequency of the laser after the initial frequency doubling with the original laser output from the pump source. The second single-frequency laser conversion channel extracts the second band of laser light from the output laser after frequency summing and outputs it.
[0060] Pump source 1 emits pump light, which is collimated and focused into the first frequency doubling crystal B1 by the collimating component. The 1064 nm pump light and the 532 nm frequency doubling light are combined by the second frequency doubling crystal H2. The 532 nm frequency doubling light is focused into the second frequency doubling crystal B2 after passing through the beam splitter 4 and the collimating component. The resulting 266 nm frequency doubling light is transmitted and output through the single-frequency output reflector 2.
[0061] The 355 nm sum-frequency light is focused onto the nonlinear crystal 14 by the collimating component ZH. The nonlinear crystal 14 forms an optical parametric oscillation in the resonant cavity composed of the first plane mirror 13 and the second plane mirror 15. The remaining 355 nm sum-frequency light is output through the beam splitter 4 and transmitted through the single-frequency output mirror 2. The 530-700 nm signal light is focused onto the third frequency-doubled crystal B3 by the collimating component ZH to generate 265-350 nm frequency-doubled light. The frequency-doubled light is transmitted through the tunable output mirror 3.
[0062] In this embodiment, the center wavelength of the pump source is 1064 nm, and the repetition frequency is 10-100 Hz.
[0063] The first plane mirror 13 is a total reflection mirror, coated with a film system of 355 nm high transmittance and 530-700 nm high reflectance; the second plane mirror 15 is a reflection mirror, coated with a film system of 355 nm high transmittance and 530-700 nm partial transmittance.
[0064] The first frequency doubling crystal B1 is an LBO crystal used to generate 532 nm by frequency doubling of 1064 nm. The front and back surfaces are coated with antireflection films of 1064 nm and 532 nm.
[0065] The second sum-frequency crystal H2 is an LBO crystal used to sum 1064 nm and 532 nm to generate 355 nm. Its front and back surfaces are coated with antireflection films of 1064 nm, 532 nm and 355 nm.
[0066] The second frequency doubling crystal B2 is a BBO crystal used to generate 266 nm by frequency doubling of 532 nm. Both ends are coated with anti-reflection protective films of 532 nm and 266 nm.
[0067] The nonlinear crystal 14 is a BBO crystal used to generate 530-700 nm signal light, with 355 nm and 530-700 nm anti-reflection protective films coated at both ends.
[0068] The third frequency doubling crystal B3 is a BBO crystal used to double the frequency of 530-700 nm signal light to generate 265-350 nm. Both ends are coated with anti-reflection protective films of 530-700 nm and 265-350 nm.
[0069] like Figure 3 As shown, in another embodiment of this application, the resonant cavity consists of two plane mirrors and a nonlinear crystal disposed between the plane mirrors. A laser crystal is used to irradiate the laser crystal with a laser, causing the laser crystal to transition and forming an excitation laser that generates laser oscillation between the two plane mirrors.
[0070] The tunable laser conversion unit includes a beam splitter 4, a collimation component ZH, a tunable module, a third frequency-doubled crystal B3, a second sum-frequency crystal H2, and a tunable output reflector 3. The beam splitter 4 transmits the frequency-doubled laser formed after the pump source has undergone initial frequency doubling. The tunable module includes two plane mirrors and a nonlinear crystal 14 disposed between the two plane mirrors (first plane mirror 13 and first plane mirror 15). The collimation component ZH focuses the transmitted frequency-doubled laser onto the nonlinear crystal 14. The nonlinear crystal 14 undergoes a transition upon irradiation, forming an excitation laser that oscillates between the two plane mirrors. The collimation component ZH focuses the laser oscillation onto the third frequency-doubled crystal B3. The laser, after being frequency-doubled again, passes through the second sum-frequency crystal H2 and is then used by the tunable output reflector 3 to obtain the final output tunable laser.
[0071] The tunable module also includes a prism M, which is positioned between two plane mirrors and is used to limit the start-up wavelength.
[0072] Specifically, the 532 nm frequency-doubled light is focused onto the nonlinear phase 14 by the collimating component ZH. The nonlinear phase 14 forms laser oscillation in the resonant cavity composed of the first plane mirror 13 and the second plane mirror 15. The prism M can limit the starting wavelength. The remaining 532 nm frequency-doubled light is reflected and output by the beam splitter 4. The resulting 750-1050 nm laser is focused onto the third frequency-doubled crystal B3 by the collimating component ZH, generating 375-525 nm frequency-doubled light. The 375-525 nm frequency-doubled light and the 750-1050 nm laser pass through the first sum-frequency crystal H1 to generate 250-350 nm sum-frequency light. The 250-350 nm sum-frequency light is transmitted and output through the tunable output mirror 3. The remaining 532 nm frequency-doubled light is focused onto the second sum-frequency crystal H2 after passing through the beam splitter 4 and the collimating component, and then sums with the remaining 1064 nm to generate 355 nm. The 355 nm sum-frequency light is transmitted and output through the 45-degree mirror 27.
[0073] The laser crystal is a titanium sapphire crystal used to generate tunable lasers in the range of 750-1050 nm. The laser crystal is placed at Brewster angle relative to the pump laser on a copper heat sink controlled by a semiconductor cooler. The temperature of the semiconductor cooler is set to 17 degrees Celsius. Both ends are coated with anti-reflection protective films of 532 nm and 750-1050 nm.
[0074] In this embodiment, the center wavelength of the pump source is 1064 nm, and the repetition frequency is 10-100 Hz.
[0075] The first plane mirror 13 is a total reflection mirror, coated with a film system of 532 nm high transmittance and 750-1050 nm high reflectance. The second plane mirror 16 is a reflection mirror, coated with a film system of 532 nm high transmittance and 750-1050 nm partial transmittance.
[0076] The first frequency doubling crystal B1 is an LBO crystal used to double the frequency of 1064 nm to 532 nm, and its front and back surfaces are coated with antireflection films of 1064 nm and 532 nm.
[0077] The second frequency doubling crystal B2 is a BBO crystal used to double the frequency of 532 nm to 266 nm, and both ends are coated with anti-reflection protective films of 532 nm and 266 nm.
[0078] The third frequency doubling crystal B3 is a BBO crystal used to double the frequency of 750-1050 nm to 375-525 nm. Both ends are coated with anti-reflection protective films of 750-1050 nm and 375-525 nm.
[0079] The first sum-frequency crystal H1 is a BBO crystal, used to sum the 750-1050 nm and 375-525 nm to generate 250-350 nm. Both ends are coated with anti-reflection protective films of 750-1050 nm, 375-525 nm and 250-350 nm.
[0080] The second sum-frequency crystal H2 is an LBO crystal used to sum and frequency 532 nm and 1064 nm to generate 355 nm. Both ends are coated with anti-reflection protective films of 532 nm, 1064 nm and 355 nm.
[0081] like Figure 2 As shown, the homogenization unit includes a beam homogenizer 201, a first homogenizing convex lens 202, a first multimode fiber 203, a second homogenizing convex lens 204, and a second multimode fiber 205.
[0082] The beam homogenizer is used to homogenize the spot of the output single-frequency laser or tunable laser. The first homogenizing convex lens is used to focus the homogenized spot onto the core of the first multimode fiber for output. The second homogenizing convex lens refocuses the output laser and couples it to the second multimode fiber. The laser that can finally ablate the spot is then output using the second multimode fiber.
[0083] The present invention also provides a patch removal system, which includes the above-mentioned tunable laser, a patch recognition module, and a removal module;
[0084] The plaque recognition module is used to identify the composition of the plaques;
[0085] The tunable laser is used to adjust the wavelength and energy of the emitted laser according to the identified patch composition.
[0086] The ablation module is used to receive tunable lasers of the corresponding wavelength band and perform precise ablation treatment on the lesion tissue according to the laser energy of the corresponding wavelength band.
[0087] More preferably, the patch recognition module adjusts the wavelength of the emitted laser according to the recognized patch type using the following method:
[0088] When the plaque is a calcified plaque, adjust the output of the tunable laser module to 355 nm laser.
[0089] When the plaque is a lipid plaque, adjust the output of the tunable laser module to 266nm laser.
[0090] When the patch is a fibrous patch or a mixed-component patch, the output of the tunable laser module is adjusted to a first tunable laser or a second tunable band laser; the first tunable laser is a 250-350 nm laser; the second tunable band laser is a 265-350 nm laser.
[0091] Obviously, the above embodiments are merely illustrative examples for clear explanation and are not intended to limit the implementation. Those skilled in the art will recognize that other variations or modifications can be made based on the above description. It is neither necessary nor possible to exhaustively list all possible implementations here. However, obvious variations or modifications derived therefrom are still within the scope of protection of this invention.
Claims
1. A tunable laser for plaque ablation, characterized in that, Includes a primary frequency doubling unit and a tunable laser conversion unit; The primary frequency doubling unit is used to perform primary frequency doubling on the original laser emitted by the pump source; The tunable laser conversion unit utilizes the optical parametric oscillation / laser oscillation formed in the resonant cavity after the initial frequency doubling of the laser, and obtains the final output tunable laser for patch ablation through frequency doubling and frequency summing; the tunable laser conversion unit includes a beam splitter, a tunable module, a collimation component, a third frequency doubling crystal, a first frequency summing crystal, and a tunable output reflector; The resonant cavity of the tunable module includes two plane mirrors and a nonlinear crystal disposed between the plane mirrors. The nonlinear crystal is a BBO crystal used to generate 750-1050nm signal light, and its two ends are coated with 532nm and 750-1050nm anti-reflection protective films. Alternatively, the resonant cavity includes two plane mirrors and a laser crystal and a prism disposed between the plane mirrors. The prism is used to limit the oscillation wavelength. The laser crystal is irradiated with a laser to cause it to transition, forming an excitation laser that oscillates between the two plane mirrors. The laser crystal is a titanium-sapphire crystal used to generate a tunable laser of 750-1050nm. The laser crystal is placed at a Brewster angle relative to the pump laser on a copper heat sink controlled by a semiconductor cooler. The temperature of the semiconductor cooler is set to 17 degrees Celsius, and both ends are coated with anti-reflection protective films of 532nm and 750-1050nm. It also includes at least one branch single-frequency laser conversion unit, which is used to perform secondary frequency doubling or summing of the laser after the initial frequency doubling to output multiple single-frequency lasers of different bands.
2. The tunable laser for patch ablation according to claim 1, characterized in that, The beam splitter transmits the frequency-doubled laser generated after the pump source is first frequency-doubled. After being collimated by the collimating component, the tunable module uses the frequency-doubled laser to generate laser oscillation. After being collimated again by the collimating component, the laser oscillation is focused onto the third frequency-doubled crystal. After the laser is frequency-doubled again, it is summed and then the final output tunable laser is obtained by using the tunable output reflector.
3. The tunable laser for patch ablation according to claim 1, characterized in that, The single-frequency laser conversion unit includes a beam splitter, a collimation component, a second frequency-doubling crystal, and a single-frequency output mirror. The two ends of the second frequency-doubling crystal are coated with anti-reflection protective films of different wavelengths. After the laser is initially frequency-doubled by the beam splitter and collimation component, the 532nm laser after the initial frequency doubling is frequency-doubled again by the second frequency-doubling crystal to output a single-frequency laser with a wavelength of 266nm.
4. The tunable laser for patch ablation according to claim 1, characterized in that, The single-frequency laser conversion unit includes a beam splitter, a collimation component, a second frequency-sum crystal, and a single-frequency output mirror. After the laser is initially frequency-doubled by the beam splitter and collimation component, it is frequency-summed using the second frequency-sum crystal. The second frequency-sum crystal is coated with anti-reflection protective films of different wavelengths at both ends, and outputs a single-frequency laser with a wavelength of 355nm.
5. The tunable laser for patch ablation according to any one of claims 1-4, characterized in that, The primary frequency doubling unit also includes a second sum-frequency crystal, and the tunable laser conversion unit includes a beam splitter, a collimation component, a tunable module, a third frequency doubling crystal, and a tunable output reflector.
6. The tunable laser for patch ablation according to any one of claims 5, characterized in that, The beam splitter transmits a single-frequency laser through one of its outgoing optical paths.
7. The tunable laser for patch ablation according to any one of claims 1-4, characterized in that, It also includes a homogenization unit for homogenizing the output laser spot, and the homogenized spot is used to erode plaques in blood vessels.
8. The tunable laser for patch ablation according to claim 7, characterized in that, The homogenization unit includes a beam homogenizer, a first homogenizing convex lens, a first multimode fiber, a second homogenizing convex lens, and a second multimode fiber. The beam homogenizer is used to homogenize the beam spot of the output single-frequency laser or tunable laser. The first homogenizing convex lens is used to focus the homogenized beam spot onto the core of the first multimode fiber for output. The second homogenizing convex lens refocuses the output laser and couples it to the second multimode fiber. The laser that can finally ablate the spot is then output using the second multimode fiber.
9. A plaque removal system, comprising the tunable laser according to any one of claims 1-8, further comprising a plaque recognition module and a removal module; The plaque recognition module is used to identify the composition of the plaques; The tunable laser is used to adjust the wavelength and energy of the emitted laser according to the identified patch composition. The ablation module is used to receive tunable lasers of the corresponding wavelength band and perform precise ablation treatment on the lesion tissue according to the laser energy of the corresponding wavelength band.
10. The plaque removal system according to claim 9, characterized in that, The patch recognition module adjusts the wavelength of the emitted laser according to the identified patch type using the following method: When the plaque is a calcified plaque, adjust the output of the tunable laser module to 355nm laser. When the plaque is a lipid plaque, adjust the output of the tunable laser module to 266nm laser. When the patch is a fibrous patch or a mixed-component patch, the output of the tunable laser module is adjusted to a first tunable laser or a second tunable band laser; the first tunable laser is a 250-350nm laser; the second tunable band laser is a 265-350nm laser.