CN116131087A - Laser ablation system based on Q-switched envelope internal chopping picosecond pulse sequence and working method - Google Patents
Laser ablation system based on Q-switched envelope internal chopping picosecond pulse sequence and working method Download PDFInfo
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- CN116131087A CN116131087A CN202310041911.8A CN202310041911A CN116131087A CN 116131087 A CN116131087 A CN 116131087A CN 202310041911 A CN202310041911 A CN 202310041911A CN 116131087 A CN116131087 A CN 116131087A
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01S—DEVICES USING THE PROCESS OF LIGHT AMPLIFICATION BY STIMULATED EMISSION OF RADIATION [LASER] TO AMPLIFY OR GENERATE LIGHT; DEVICES USING STIMULATED EMISSION OF ELECTROMAGNETIC RADIATION IN WAVE RANGES OTHER THAN OPTICAL
- H01S3/00—Lasers, i.e. devices using stimulated emission of electromagnetic radiation in the infrared, visible or ultraviolet wave range
- H01S3/10—Controlling the intensity, frequency, phase, polarisation or direction of the emitted radiation, e.g. switching, gating, modulating or demodulating
- H01S3/11—Mode locking; Q-switching; Other giant-pulse techniques, e.g. cavity dumping
- H01S3/1123—Q-switching
- H01S3/115—Q-switching using intracavity electro-optic devices
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- A—HUMAN NECESSITIES
- A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
- A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
- A61B18/00—Surgical instruments, devices or methods for transferring non-mechanical forms of energy to or from the body
- A61B18/18—Surgical instruments, devices or methods for transferring non-mechanical forms of energy to or from the body by applying electromagnetic radiation, e.g. microwaves
- A61B18/20—Surgical instruments, devices or methods for transferring non-mechanical forms of energy to or from the body by applying electromagnetic radiation, e.g. microwaves using laser
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01S—DEVICES USING THE PROCESS OF LIGHT AMPLIFICATION BY STIMULATED EMISSION OF RADIATION [LASER] TO AMPLIFY OR GENERATE LIGHT; DEVICES USING STIMULATED EMISSION OF ELECTROMAGNETIC RADIATION IN WAVE RANGES OTHER THAN OPTICAL
- H01S3/00—Lasers, i.e. devices using stimulated emission of electromagnetic radiation in the infrared, visible or ultraviolet wave range
- H01S3/005—Optical devices external to the laser cavity, specially adapted for lasers, e.g. for homogenisation of the beam or for manipulating laser pulses, e.g. pulse shaping
- H01S3/0085—Modulating the output, i.e. the laser beam is modulated outside the laser cavity
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- A—HUMAN NECESSITIES
- A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
- A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
- A61B18/00—Surgical instruments, devices or methods for transferring non-mechanical forms of energy to or from the body
- A61B18/18—Surgical instruments, devices or methods for transferring non-mechanical forms of energy to or from the body by applying electromagnetic radiation, e.g. microwaves
- A61B18/20—Surgical instruments, devices or methods for transferring non-mechanical forms of energy to or from the body by applying electromagnetic radiation, e.g. microwaves using laser
- A61B2018/2035—Beam shaping or redirecting; Optical components therefor
- A61B2018/2045—Choppers
Abstract
The invention discloses a Q-switched envelope internal chopping picosecond pulse sequence-based laser ablation system and a working method thereof, wherein the system comprises a laser and a laser catheter, and the laser comprises a laser generation module, a laser amplification module, a frequency multiplication module and an optical chopping module; the laser generation module emits 1064nm nanosecond Q-switched pulse laser, the laser is amplified by the laser amplification module, then the laser enters the frequency multiplication module to realize 355nm or 266nm pulse output, finally the optical chopping module realizes picosecond pulse sequence output in the Q-switched envelope, and the laser generation module and the optical chopping module are matched to inhibit laser initial pulse.
Description
Technical Field
The invention relates to the technical field of laser ablation, in particular to a Q-switched envelope internal chopping picosecond pulse sequence-based laser ablation system and a working method thereof.
Background
The laser ablation technology can treat restenosis lesions through plaque volume reduction and modification, and can not damage normal tissues and a bracket structure, so that the effect of treating diseases such as atherosclerosis and the like is achieved. Based on the method, in ultraviolet laser atheromatous plaque ablation, 355nm solid laser usually adopts a delay mode to decompose single pulse into double pulses with different polarizations, so that single pulse energy is reduced, an energy-transmitting optical fiber is protected, and ablation effect is improved. The double pulse laser ablation changes the surface property of plaque tissue through the first lower energy laser pulse, so that the energy coupling of the subsequent pulse is enhanced, and the ablation efficiency of the subsequent pulse is improved. The double pulse mode lowers the ablation threshold of the second laser pulse because the first laser pulse alters the optical properties of the tissue surface. In addition, the interaction of the second high energy pulse with the plume created by the first low energy pulse can create finer ablation products. The nanosecond laser can be decomposed into a plurality of picosecond pulse lasers in the pulse envelope by adopting an optical chopping technology, so that the ablation product is further refined.
Picosecond lasers have been successfully used in the medical field, and in dermatology and orthopedics, the use of picosecond laser devices has shown good results for skin treatment, including the treatment of benign pigmented lesions and acne scars, and the removal of tattoos and various skin vascular diseases, and the repair of skin. The picosecond pulse can instantly heat a target chromophore in skin tissue, the higher peak power can improve the ablation efficiency, and the picosecond laser pulse width is far smaller than the thermal relaxation time of the tissue, so that the damage to surrounding healthy tissue is smaller. When picosecond lasers are used to remove tattoos, the pressure generated by the picosecond pulses can result in high peak tensile stresses that can fracture the ink particles by an opto-mechanical impact, which is not possible in nanosecond pulse therapy. The picosecond laser pulse has short duration and high peak power, and the ink particles can be subjected to higher opto-mechanical impact, so that the particle breaking efficiency is improved.
The application of picosecond lasers to atheromatous plaque ablation holds significant promise, and ultrafast pulse ablation offers a possibility of gasifying plaque without damaging the surface. The ultra-fast pulses of high peak power enable nonlinear absorption of laser energy by the active substance, limiting the range of laser interaction with tissue in three dimensions to a focal volume. When the irradiance of the laser exceeds the optical breakdown threshold of plasma formation caused by multiphoton ionization, ultra-fast ablation occurs, which is finer than nanosecond laser ablation products, and heat accumulation and heat damage outside the focal volume are minimized, protecting healthy vascular tissue.
However, picosecond laser is not applied to the field of ablation of atherosclerosis plaque at present, and the main reason is that the ablation of atherosclerosis plaque belongs to interventional therapy, the ablation effect can be generated only by laser with a specific frequency band, the picosecond laser pulse string output with large energy and stable output can not be realized after the nonlinear frequency of the laser is converted to the specific frequency band in the prior art, on the other hand, the picosecond laser applied to skin therapy at present adopts mechanical chopping to form a continuous laser into a light sequence, the structure is complicated, the small-size integration is inconvenient, and the mechanical chopping adopts a mechanical structure to block a laser propagation path, heat accumulation is caused after long-time use, and the service life is seriously influenced.
Disclosure of Invention
Therefore, the invention aims to provide a laser ablation system and a working method based on a Q-switched envelope internal chopping picosecond pulse sequence, which utilize optical chopping and the Q-switched envelope to combine frequency-doubled 355nm or 266nm laser to form picosecond pulse sequence laser, the Q-switched envelope ensures the energy of picosecond pulse strings, and the output continuous light is converted into a pulse sequence through the optical chopping, so that 355nm or 266nm picosecond pulse sequence laser is finally output.
In order to achieve the above purpose, the invention provides a laser ablation system based on a Q-switched envelope internal chopping picosecond pulse sequence, which comprises a laser generation module, a laser amplification module, a frequency multiplication module and an optical chopping module;
the laser generating module comprises a pumping source, a Q-switching unit, a resonant cavity unit and a gain medium; the pumping source is used for outputting original laser to be incident to the gain medium, and the gain medium forms Q-switched pulse laser under the combined action of the Q-switched unit and the resonant cavity unit;
the laser amplifying module is used for amplifying the formed Q-switched pulse laser;
the frequency doubling module is used for carrying out frequency doubling on the amplified Q-switched pulse laser to generate 355nm or 266nm laser under the Q-switched envelope;
and the optical chopping module is used for chopping 355nm or 266nm laser under the Q-switched envelope to realize picosecond pulse sequence output under the Q-switched envelope.
Further preferably, the Q-switching unit includes a first quarter-wave plate, an electro-optical modulator, and a first polarizer that are sequentially disposed; the gain medium is disposed behind the first polarizer, and the resonant cavity unit includes a total reflection mirror disposed in front of the first quarter-wave plate and a coupling-out mirror disposed behind the gain medium.
Further preferably, the laser amplifying module comprises a laser amplifier and a collimation polarization unit, the laser amplifier is arranged behind the resonant cavity unit, and the collimation polarization unit comprises a second convex lens, a second concave lens and a second half-wave plate which are arranged behind the laser amplifier in sequence; the second convex lens and the second concave lens are used for enabling laser beams amplified by the laser amplifier to be condensed and focused; the second half-wave plate is used for adjusting the polarization direction of the focused laser.
Further preferably, the laser amplifying module further comprises a first 45-degree reflecting mirror and a second 45-degree reflecting mirror arranged between the laser amplifier and the collimating and polarizing unit; the first 45-degree reflecting mirror and the second 45-degree reflecting mirror are oppositely arranged at an angle of 90 degrees.
Further preferably, the frequency doubling module comprises a first nonlinear crystal and a second nonlinear crystal; the first nonlinear crystal is used for carrying out first frequency multiplication on the laser output by the laser amplifying module, and the second nonlinear crystal is used for carrying out second frequency multiplication on the laser after the first frequency multiplication to generate 355nm or 266nm laser under the Q-switched envelope.
Further preferably, when the frequency multiplication module is frequency tripling, the first nonlinear crystal is an LBO frequency multiplication crystal for generating 532nm with 1064nm frequency multiplication, and front and rear surfaces are plated with 1064nm and 532nm antireflection film systems; the second nonlinear crystal is an LBO sum frequency crystal for sum frequency generation of 355nm laser light from 1064nm and 532nm laser light.
Further preferably, when the frequency multiplication module is quadruple frequency, the first nonlinear crystal is LBO frequency multiplication crystal for generating 532nm with 1064nm frequency multiplication, and front and rear surfaces are plated with 1064nm and 532nm antireflection film systems; the second nonlinear crystal is BBO frequency doubling crystal and is used for generating 266nm laser by 532nm frequency doubling, and both ends of the second nonlinear crystal are plated with 532nm and 266nm anti-reflection protective films.
Further preferably, the optical chopper module comprises a filter mirror, an optical modulator and a second polarizer which are sequentially arranged from front to back; the filter lens is used for filtering 355nm or 266nm laser under the output Q-switched envelope, the optical modulator is used for modulating the 355nm or 266nm laser after filtering, and the second polaroid is used for emitting the modulated laser parallel to the light passing direction.
Further, it is preferable that the laser generating module further includes a second quarter wave plate, a third quarter wave plate, and a first half wave plate and an isolator disposed behind the resonant cavity unit, which are disposed at both ends of the gain medium.
The invention also provides a working method of the Q-switched envelope internal chopping picosecond pulse sequence laser ablation system, which is implemented based on the Q-switched envelope internal chopping picosecond pulse sequence laser ablation system and comprises the following steps:
the electro-optical modulator is controlled to be turned on or off by setting an external pulse signal through a power supply and a drive;
when the electro-optical modulator has no high voltage, the pumping source outputs continuous laser, and the energy level inversion particle number on the gain medium is continuously consumed; after the continuous laser enters the laser amplifier, the reverse particle number in the gain medium of the laser amplifier is consumed, the light modulator is closed, the light passing direction of the second polaroid is perpendicular to the polarization direction of the emergent laser, and the whole laser does not have laser output;
when high voltage is loaded on the electro-optical modulator, a large amount of reverse particles are accumulated in the gain medium, the high voltage is removed, the pulse laser is output and amplified by the laser amplifier, the optical modulator works according to a set frequency, the polarization direction of the modulated laser is parallel to the light passing direction of the second polaroid, and stable Q-switched envelope internal chopping picosecond pulse laser sequence output is realized.
Compared with the existing laser ablation system, the system utilizes the light modulator to realize picosecond pulse output in the Q-switched envelope, and the Q-switched envelope ensures the energy of picosecond pulse trains. And pulse output with stable energy is realized through the cooperation of the two light modulators; compared with the existing ablation system, the ablation system has limited ablation efficiency, the fragments are not small enough and are more easily damaged, the system can improve the ablation efficiency, further refine the tissue fragments after ablation, and directly ablate the plaque without damaging the surface layer.
Two quarter wave plates are added in the optical path, the 1064nm Q-switched pulse laser output by the output mirror of the input-output coupling is incident into the isolator through the half wave plate to adjust the polarization direction, damage to devices caused by return light after amplification to the resonant cavity is avoided, the space hole burning effect is controlled, and the thermal effect is relieved.
Drawings
Fig. 1 is a schematic diagram of a laser ablation system based on a chopped picosecond pulse sequence within a Q-switched envelope.
Fig. 2 is a schematic structural diagram of a laser ablation system based on a chopped picosecond pulse sequence within a tuning Q envelope in example 1.
Fig. 3 is a schematic structural diagram of a laser ablation system based on a chopped picosecond pulse sequence within a tuning Q envelope in example 2.
Fig. 4 is a flowchart of the operation of the laser ablation system based on the chopped picosecond pulse sequence within the tuning Q envelope in example 3.
Fig. 5 is a waveform diagram of the output of the laser ablation system based on chopped picosecond pulse sequences within the Q-switched envelope.
In the figure:
1. a total reflection mirror; 2. a first quarter wave plate; 3. an electro-optic modulator; 4. a first polarizing plate; 6. a gain medium; 5. a second quarter wave plate; 7. a third quarter wave plate; 8. a coupling-out mirror; 9. a first half-wave plate; 10. an isolator; 11. a first convex lens; 12. a first concave lens; 13. a laser amplifier; 16. a second convex lens; 17. a second concave lens; 18. a second half-wave plate; 19. a first nonlinear crystal; 20. a second nonlinear crystal; 21. a filter mirror; 22. an optical modulator; 23. and a second polarizing plate.
Detailed Description
The invention is described in further detail below with reference to the drawings and the detailed description.
As shown in fig. 1, an embodiment of the present invention provides a laser ablation system based on a Q-switched envelope internal chopping picosecond pulse sequence, which includes a laser and a laser catheter, wherein the laser includes a laser generating module, a laser amplifying module, a frequency doubling module and an optical chopping module;
the laser generating module comprises a pumping source, a Q-switching unit, a resonant cavity unit and a gain medium; the pumping source is used for outputting original laser to be incident to the gain medium, and the gain medium forms Q-switched pulse laser under the combined action of the Q-switched unit and the resonant cavity unit;
the laser amplifying module is used for amplifying the formed Q-switched pulse laser;
the frequency doubling module is used for carrying out frequency doubling on the amplified Q-switched pulse laser to generate 355nm or 266nm laser under the Q-switched envelope;
and the optical chopping module is used for chopping 355nm or 266nm laser under the Q-switched envelope to realize picosecond pulse sequence output under the Q-switched envelope.
Example 1 is shown in fig. 2:
the Q-switching unit comprises a first quarter wave plate 2, an electro-optic modulator 3 and a first polaroid 4 which are sequentially arranged; the gain medium 6 is arranged behind the first polarizer 4 and the resonator element comprises a total reflection mirror 1 arranged in front of the first quarter wave plate 2 and a coupling-out mirror 8 arranged behind the gain medium 6.
The laser amplifying module comprises a laser amplifier 13 and a collimation polarization unit, wherein the laser amplifier 13 is arranged behind the resonant cavity unit, and the collimation polarization unit comprises a second convex lens 16, a second concave lens 17 and a second half-wave plate 18 which are sequentially arranged behind the laser amplifier 13; the second convex lens 16 and the second concave lens 17 are used for converging and focusing the laser beam after the laser amplifier 13 amplifies; the second half-wave plate 18 is used to adjust the polarization direction of the focused laser light.
Further preferably, the frequency doubling module comprises a first nonlinear crystal 19 and a second nonlinear crystal 20; the first nonlinear crystal 19 is used for performing first frequency multiplication on the laser output by the laser amplifying module, the second nonlinear crystal 20 is used for performing second frequency multiplication on the laser after the first frequency multiplication to generate 266nm laser under the Q-switched envelope, or is used for performing frequency summation on fundamental frequency light and the laser after the first frequency multiplication to generate 355nm laser under the Q-switched envelope.
The optical chopper module comprises a filter mirror 21, an optical modulator 22 and a second polaroid sheet 23 which are sequentially arranged from front to back; the filter mirror 21 is used for filtering 355nm or 266nm laser under the output Q-switched envelope, the optical modulator 22 is used for modulating the 355nm or 266nm laser after filtering, the second polaroid 23 is used for limiting the polarization direction of the transmitted light, and the chopper is realized by matching with the optical modulator.
The gain medium 6 forms pulse laser under the combined action of a resonant cavity formed by the quarter wave plate I2, the electro-optical modulator 3, the Q-switching module formed by the first polaroid 4, the total reflection mirror 1 and the coupling output mirror 8. The 1064nm Q-switched pulse laser output by the output coupling mirror 8 is incident on the laser amplifier 13 to amplify the 1064nm Q-switched laser. The laser beam is condensed and focused through a second convex lens 16 and a second concave lens 17, the polarization direction is adjusted through a second half wave plate 18, the laser beam is incident into a first nonlinear crystal 19, a frequency tripling process or a frequency quadrupling process is realized through the first nonlinear crystal 19 and a second nonlinear crystal 20, 355nm or 266nm laser is obtained, the laser beam is filtered through a filter 21, and the laser beam is incident into an optical chopper module formed by an optical modulator 22 and a second polarizing plate 23, so that picosecond pulse sequence output under a Q-switched envelope is realized.
Example 2
As shown in fig. 3, in order to control the spatial hole burning effect and mitigate the thermal effect, a second quarter wave plate 5 and a third quarter wave plate 7 may be added at both ends of the gain medium 6 in the optical path. And a first convex lens 11 and a first concave lens 12 are arranged behind the coupling-out mirror 8; the 1064nm Q-switched pulse laser output by the coupling output mirror 8 is incident into the isolator 10 through the first half-wave plate 9 to adjust the polarization direction, so that the amplified return light is prevented from returning to the resonant cavity to damage the device. The laser beam is collimated and expanded by the first convex lens 11 and the first concave lens 12 and then is incident into the laser amplifier 13, so that the amplifying-stage crystal rod is fully utilized, and the 1064nm Q-switched laser is amplified. The laser amplification module further comprises a first 45-degree reflecting mirror 14 and a second 45-degree reflecting mirror 15 which are arranged between the laser amplifier 13 and the collimation polarization unit; the first 45-degree reflecting mirror 14 and the second 45-degree reflecting mirror 15 are oppositely arranged at an angle of 90 degrees, so that higher space utilization rate is realized.
The pump source was an LD-side pump module having a center wavelength of 808 nm. The total reflection mirror 1 is a flat concave mirror and is plated with a 1064nm high-reflection film system; the first 45-degree reflecting mirror 14 and the second 45-degree reflecting mirror 15 are plane mirrors, and are plated with 1064nm high-reflection film systems; the coupling-out mirror 8 is a plane mirror, and is plated with a 1064nm part of transparent film system.
The electro-optic modulator 3 is KD * P, the front and back surfaces are plated with 1064nm antireflection film systems.
The laser amplifier 13 is an LD-side pump amplification module.
When the frequency multiplication module is frequency tripling, the first nonlinear crystal 19 is an LBO frequency multiplication crystal and is used for generating 532nm with 1064nm frequency multiplication, and the front and rear surfaces are plated with 1064nm and 532nm antireflection film systems; the second nonlinear crystal 20 is an LBO sum frequency crystal for sum frequency generation of 355nm laser light with 1064nm and 532nm laser light.
When the frequency multiplication module is four times frequency, the first nonlinear crystal 19 is an LBO frequency multiplication crystal and is used for generating 532nm with 1064nm frequency multiplication, and the front and rear surfaces are plated with 1064nm and 532nm antireflection film systems; the second nonlinear crystal 20 is BBO frequency doubling crystal and is used for generating 266nm laser by 532nm frequency doubling, and both ends of the second nonlinear crystal are plated with 532nm and 266nm anti-reflection protective films.
The filter mirror 21 is a plane mirror coated with 1064nm, 532nm high reflection and 355nm high transmission film system.
The optical modulator 22 is KD * P, etc. electro-optical modulation devices and acousto-optic modulation devices.
Embodiment 3, as shown in fig. 4, the invention further provides a working method of the Q-switched envelope internal chopping picosecond pulse sequence laser ablation system, which is implemented based on the Q-switched envelope internal chopping picosecond pulse sequence laser ablation system and comprises the following steps:
the electro-optical modulator is controlled to be turned on or off by setting an external pulse signal through a power supply and a drive;
when the electro-optical modulator has no high voltage, the pumping source outputs continuous laser, and the energy level inversion particle number on the gain medium is continuously consumed; after the continuous laser enters the laser amplifier, the reverse particle number in the gain medium of the laser amplifier is consumed, the light modulator is closed, the light passing direction of the second polaroid is perpendicular to the polarization direction of the emergent laser, and the whole laser does not have laser output;
when high voltage is loaded on the electro-optical modulator, a large amount of reverse particles are accumulated in the gain medium, the high voltage is removed, the pulse laser is output and amplified by the laser amplifier, the optical modulator works according to a set frequency, the polarization direction of the modulated laser is parallel to the light passing direction of the second polaroid, and stable Q-switched envelope internal chopping picosecond pulse laser sequence output is realized.
As shown in fig. 5, the laser output waveform is L1, which is continuous laser for suppressing the excessive energy of the first pulse and consuming the reversed particle number when no pulse is output, and at this time, the optical chopper is controlled to be turned off, and the system does not output laser; l2 is a schematic diagram of a modulating Q pulse envelope waveform; l3 is a schematic diagram of a chopped picosecond pulse train waveform.
The optical chopping technology adopted by the application can realize a series of picosecond pulse sequences with high peak power in the Q-switched envelope of the nanosecond laser, and the Q-switched envelope ensures the energy of the laser pulse sequences, so that the lesion tissues are sufficiently eroded. The picosecond pulse output can be realized by utilizing an optical chopping technology without a mode locking technology, one laser pulse is decomposed into a plurality of pulses in the envelope of the picosecond pulse, so that the separation of the laser pulse on a time sequence is realized, the interaction between the subsequent pulse in a pulse train and the plume generated by the previous pulse can generate finer ablation products, the energy of the picosecond pulse in the front edge of the integral envelope is lower, and the energy is gradually increased before reaching a peak value, so that the ablation efficiency even exceeding that of double-pulse laser ablation is realized, and the ablation effect is improved.
In addition, the first pulse of the laser has the phenomenon of overlarge energy due to long accumulation time of reverse particle count, and in order to inhibit the first pulse, an external pulse signal is set through a power supply and a drive to control the electro-optical modulator when the laser does not need to output pulse laser, so that the resonant cavity unit continuously operates, and the terminal light modulator is in a closed state, so that continuous light cannot be output. When the Q-switched crystal is not high-voltage, the resonant cavity unit continuously operates, and the output continuous light consumes the inverted particle number of the continuous light through the amplifier. When the Q-switched crystal is loaded with high voltage, the resonant cavity unit stops oscillating, the counter-rotating particle number of the gain medium is accumulated, and then the high voltage on the Q-switched crystal is rapidly removed, so that pulse laser output is realized. Since the pulse laser is continuously consumed before the amplification stage gain medium inverts the particle count after entering the amplifier, the pulse laser with stable energy can be output.
When pulse output is not needed, the resonant cavity unit is enabled to emit continuous laser, the counter-rotating particle numbers of the resonant cavity unit and the gain medium of the amplifier can be consumed simultaneously, and the output continuous laser is removed through the electro-optical modulator. The method eliminates the hidden trouble of damage to plaque ablation system coupling devices, ablation catheters and human bodies caused by overlarge initial pulse energy.
It is apparent that the above examples are given by way of illustration only and are not limiting of the embodiments. Other variations or modifications of the above teachings will be apparent to those of ordinary skill in the art. It is not necessary here nor is it exhaustive of all embodiments. While still being apparent from variations or modifications that may be made by those skilled in the art are within the scope of the invention.
Claims (10)
1. The laser ablation system based on the Q-switched envelope internal chopping picosecond pulse sequence is characterized by comprising a laser and a laser catheter, wherein the laser comprises a laser generation module, a laser amplification module, a frequency multiplication module and an optical chopping module;
the laser generation module comprises a pumping source, a Q-switching unit, a resonant cavity unit and a gain medium; the pumping source is used for outputting original laser to be incident to the gain medium, and the gain medium forms Q-switched pulse laser under the combined action of the Q-switched unit and the resonant cavity unit;
the laser amplifying module is used for amplifying the formed Q-switched pulse laser;
the frequency multiplication module is used for multiplying the amplified Q-switched pulse laser to generate 355nm or 266nm laser under the Q-switched envelope;
the optical chopping module is used for chopping 355nm or 266nm laser under the Q-switched envelope to realize picosecond pulse sequence output under the Q-switched envelope.
2. The Q-switched envelope based chopped picosecond pulse sequence laser ablation system of claim 1, wherein the Q-switched unit comprises a first quarter wave plate, an electro-optic modulator, and a first polarizer arranged in sequence; the gain medium is disposed after the first polarizer, and the resonant cavity unit includes a total reflection mirror disposed before the first quarter wave plate and a coupling-out mirror disposed after the gain medium.
3. The Q-switched envelope internal chopping picosecond pulse sequence based laser ablation system according to claim 1, wherein the laser amplification module comprises a laser amplifier and a collimating and polarizing unit, the laser amplifier is arranged behind the resonant cavity unit, and the collimating and polarizing unit comprises a second convex lens, a second concave lens and a second half-wave plate which are arranged behind the laser amplifier in sequence; the second convex lens and the second concave lens are used for enabling laser beams amplified by the laser amplifier to be condensed and focused; the second half-wave plate is used for adjusting the polarization direction of the focused laser.
4. The Q-switched envelope based chopped picosecond pulse sequence laser ablation system of claim 3, further comprising a first 45 degree mirror and a second 45 degree mirror disposed between the laser amplifier and the collimating and polarizing unit; the first 45-degree reflecting mirror and the second 45-degree reflecting mirror are oppositely arranged at an angle of 90 degrees.
5. The Q-switched envelope based chopped picosecond pulse train laser ablation system of claim 1, wherein the frequency doubling module comprises a first nonlinear crystal and a second nonlinear crystal; the first nonlinear crystal is used for carrying out first frequency multiplication on the laser output by the laser amplifying module, and the second nonlinear crystal is used for carrying out second frequency multiplication on the laser after the first frequency multiplication to generate 266nm laser under the Q-switched envelope; or the laser is used for carrying out frequency summation on the fundamental frequency light and the laser after the first frequency multiplication to generate 355nm laser under the Q-switched envelope.
6. The laser ablation system based on the Q-switched envelope internal chopping picosecond pulse sequence according to claim 5, wherein when the frequency multiplication module is frequency tripled, the first nonlinear crystal is an LBO frequency multiplication crystal for generating 532nm with 1064nm frequency multiplication, and front and rear surfaces are plated with 1064nm and 532nm antireflection film systems; the second nonlinear crystal is LBO sum frequency crystal, which is used for generating 355nm laser with 1064nm and 532nm laser sum frequency, and the front and back surfaces are plated with 1064nm, 532nm and 355nm antireflection film systems.
7. The laser ablation system based on the Q-switched envelope internal chopping picosecond pulse sequence according to claim 5, wherein when the frequency multiplication module is quadruple frequency, the first nonlinear crystal is LBO frequency multiplication crystal for generating 532nm with 1064nm frequency multiplication, and front and rear surfaces are plated with 1064nm and 532nm antireflection film systems; the second nonlinear crystal is BBO frequency doubling crystal and is used for generating 266nm laser by 532nm frequency doubling, and both ends of the second nonlinear crystal are plated with 532nm and 266nm anti-reflection protective films.
8. The Q-switched envelope internal chopping picosecond pulse train based laser ablation system according to any of claims 1-5, wherein the optical chopping module comprises a filter mirror, an optical modulator and a second polarizer arranged sequentially from front to back; the filter lens is used for filtering 355nm or 266nm laser under the output Q-switched envelope, the optical modulator is used for modulating the 355nm or 266nm laser after filtering, the second polaroid is used for limiting the light passing polarization direction, and the second polaroid is matched with the optical modulator to realize chopping.
9. The Q-switched envelope based chopped picosecond pulse train laser ablation system of any one of claims 1-5, wherein the laser generation module further comprises a second quarter wave plate, a third quarter wave plate disposed across the gain medium and a first half wave plate and an isolator disposed after the resonant cavity unit.
10. A method for operating a Q-switched envelope internal chopping picosecond pulse train laser ablation system, characterized in that the Q-switched envelope internal chopping picosecond pulse train based laser ablation system according to any one of the preceding claims 1-9 is implemented, comprising the steps of:
the electro-optical modulator is controlled to be turned on or off by setting an external pulse signal through a power supply and a drive;
when the electro-optical modulator has no high voltage, the pumping source outputs continuous laser, and the energy level inversion particle number on the gain medium is continuously consumed; after the continuous laser enters the laser amplifier, the reverse particle number in the gain medium of the laser amplifier is consumed, the light modulator is closed, the light passing direction of the second polaroid is perpendicular to the polarization direction of the emergent laser, and the whole laser does not have laser output;
when high voltage is loaded on the electro-optical modulator, a large amount of reverse particles are accumulated in the gain medium, the high voltage is removed, the pulse laser is output and amplified by the laser amplifier, the optical modulator works according to a set frequency, the polarization direction of the modulated laser is parallel to the light passing direction of the second polaroid, and stable Q-switched envelope internal chopping picosecond pulse laser sequence output is realized.
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN116706664A (en) * | 2023-08-02 | 2023-09-05 | 深圳市中科融光医疗科技有限公司 | High-energy space-time coupled laser device and application method |
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN116706664A (en) * | 2023-08-02 | 2023-09-05 | 深圳市中科融光医疗科技有限公司 | High-energy space-time coupled laser device and application method |
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