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CN-115513765-B - Plaque ablation system based on Q-switched mode locking technology

CN115513765BCN 115513765 BCN115513765 BCN 115513765BCN-115513765-B

Abstract

The invention discloses a plaque ablation system based on a Q-switched mode locking technology, which comprises a Q-switched mode locking component, a laser amplifying component, an adjustable reflector, a frequency-tripled output branch and a laser ablation module, wherein pump light output by a pump source is focused on a laser crystal to form Q-switched mode locking pulse laser output by a resonant cavity, 355nm laser or 266nm laser is output by reflecting amplified laser to the frequency-tripled output branch or the frequency-quadrupled output branch, and high-energy Q-switched mode locking 355nm and 266nm laser output is realized by combining the laser amplifying technology with a nonlinear optical frequency conversion technology on the basis of the Q-switched mode locking pulse laser. The method realizes the switchable output of the pulse mode, switches lasers with different frequency bands for different types of plaques, ensures that the plaque ablation process is more accurate, improves the plaque ablation rate, and achieves better ablation effect.

Inventors

  • ZHAO SHIYONG
  • JIA ZONGNAN
  • LI GUANGXI
  • WU XINING
  • ZHANG QINGJIE

Assignees

  • 天津恒宇医疗科技有限公司

Dates

Publication Date
20260508
Application Date
20221027

Claims (6)

  1. 1. The plaque ablation system based on the Q-switched mode locking technology is characterized by comprising a Q-switched mode locking assembly, a laser amplifying assembly, an adjustable reflector, a frequency tripled output branch, a frequency quadrupled output branch, a laser ablation module and a controller; The Q-switched locking module is used for realizing pulse laser output, and comprises Q-switched locking pulse laser output with stable repetition frequency through a Q switch and a locking element, Q-switched pulse output when the Q switch is singly used and locking pulse output when the locking element is singly used, wherein the Q-switched locking module comprises a collimation module, a laser crystal, the Q switch, a resonant cavity and the locking element, the collimation module is used for collimating pumping light output by a pumping source and then focusing the pumping light into the laser crystal, output laser is modulated under the action of the Q switch and the locking element to realize Q-switched locking pulse output, Q-switched pulse output and locking pulse output, the Q switch is an acousto-optic Q switch, the front surface and the rear surface of the Q switch are plated with 1064nm antireflection film systems, the locking element is a saturated absorber of Cr4 < + >: YAG, gaAs, SESAM, and the Q-switched pulse output when the Q-switched element is singly used is provided; when the mode locking element is independently used, a mode locking pulse is output, plaque is removed under the condition of not damaging the fiber cap, so that subsurface ablation is realized, and volume reduction is realized on the premise of avoiding plaque rupture; the Q-switching mode locking device is used for outputting Q-switching mode locking pulse when the Q-switching element and the mode locking element are used, and the Q-switching mode locking device is used for decomposing one laser pulse into a plurality of pulses in the envelope of the laser pulse without a delay light path, so that the separation of the laser pulse on a time sequence is realized, the energy of the mode locking pulse in the front edge of the envelope of the Q-switching pulse is lower, and the energy is gradually increased before reaching a peak value; The laser amplifying assembly is used for amplifying the output pulse laser beam and amplifying the laser beam after the beam expansion; The adjustable reflector reflects the amplified laser to the frequency-tripled output branch or the frequency-quadrupled output branch through moving the position or rotating the angle; when the adjustable reflector moves or rotates to be coaxial with the frequency tripling output branch, the reflected laser is subjected to frequency tripling by utilizing a nonlinear crystal, and 355nm laser is output; when the adjustable reflector moves or rotates to be coaxial with the quadruple frequency output branch, the quadruple frequency output branch is used for carrying out quadruple frequency on reflected laser by utilizing a nonlinear crystal, and 266nm laser is output; The controller controls the start and stop of a Q switch and a mode locking element in the Q-switched mode locking assembly according to the identified plaque type and a set threshold value, controls the adjustable reflector to move or rotate to a frequency tripled output branch or a frequency quadrupled output branch, and switches and outputs 355nm laser or 266nm laser, so that different plaques are selectively eroded by using high photon energy of ultraviolet laser; And the laser ablation module is used for performing plaque ablation by utilizing the laser output by the frequency-tripled output branch or the frequency-quadrupled output branch.
  2. 2. The plaque ablation system based on the Q-switched mode locking technology according to claim 1, wherein the laser amplification assembly comprises a first half-wave plate, an isolator, a beam expansion module and a laser amplification module, the first half-wave plate is used for adjusting the polarization direction of pulsed laser light, so that the pulsed laser light is incident into the isolator, unidirectional transmission of the laser light is achieved through isolation of the isolator, and the laser amplification module is used for amplifying the laser light which is isolated and is expanded by the beam expansion module.
  3. 3. The plaque ablation system based on the Q-switched mode locking technology according to claim 1, wherein the frequency tripler output branch comprises a first beam shrinking module, a second half-wave plate, a first nonlinear crystal and a second nonlinear crystal, wherein the first beam shrinking module is used for carrying out beam shrinking focusing on laser reflected by the adjustable reflector, the second half-wave plate is used for adjusting the polarization direction, the laser is incident on the first nonlinear crystal, the first nonlinear crystal is used for doubling the frequency, the second nonlinear crystal is used for summing the frequency, and 355nm laser after the frequency tripler is output.
  4. 4. The plaque ablation system based on the Q-switched mode locking technology according to claim 1, wherein the quadruple frequency output branch comprises a second beam shrinking module, a third half-wave plate, a third nonlinear crystal and a fourth nonlinear crystal, wherein the second beam shrinking module is used for carrying out beam shrinking focusing on laser reflected by the adjustable reflector, adjusting the polarization direction by using the third half-wave plate, then, the laser is incident on the third nonlinear crystal, and the laser with 266nm after frequency quadruple is output by using sequential frequency doubling of the third nonlinear crystal and the fourth nonlinear crystal.
  5. 5. The plaque ablation system based on the Q-switched mode locking technology according to claim 3, wherein the first nonlinear crystal is an LBO frequency doubling crystal used for generating 532nm frequency doubling of 1064nm, front and rear surfaces are plated with 1064nm and 532nm antireflection film systems, the second nonlinear crystal is an LBO frequency doubling crystal used for generating 355nm frequency summation of 1064nm and 532nm, and front and rear surfaces are plated with 1064nm, 532nm and 355nm antireflection film systems.
  6. 6. The plaque ablation system based on the Q-switched mode locking technology according to claim 4, wherein the third nonlinear crystal is a BBO frequency doubling crystal and is used for generating 532nm frequency doubling of 1064nm, front and rear surfaces are plated with 1064nm and 532nm antireflection film systems, the fourth nonlinear crystal is a BBO frequency doubling crystal and is used for generating 266nm frequency doubling of 532nm, and two ends are plated with 532nm and 266nm antireflection protective films.

Description

Plaque ablation system based on Q-switched mode locking technology Technical Field The invention relates to the technical field of laser ablation, in particular to a plaque ablation system based on a Q-switching mode locking technology. Background In ultraviolet laser atherectomy, 355nm solid laser usually adopts a delayed mode to decompose single pulse into double pulses, thereby improving the ablation effect and achieving the purpose of protecting the optical fiber in the catheter. The time sequence double-pulse laser ablation changes the surface property of plaque tissues through the first 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, also because the laser alters the optical properties of the tissue surface. In addition, the interaction of the second pulse with the plume generated by the first pulse can produce finer ablation products. Plasma may be generated during ablation of the single pulse nanosecond laser, the plasma shielding effect may reduce absorption of laser energy by plaque tissue, and the double pulse working mode may reduce the plasma shielding effect. In the "double pulse" nanosecond laser ablation process, the low energy pulse precedes the high energy pulse (referred to as "low-high double pulse" laser ablation), and under similar laser energy input, a higher ablation rate can be produced than in the "high-low double pulse" or "single pulse" laser ablation. The ablation process of the first low energy laser pulse may create a localized low gas density ambient target surface directly over the tissue, which may reduce the plasma shielding effect, thereby increasing the ablation rate of the second laser pulse. The Q-switched mode locking technology (QML) can improve the peak power of a pulse laser, a series of high-peak-power mode locking pulse sequences are realized in the Q-switched envelope of the pulse laser, the amplitude of the mode locking pulse sequences is periodically modulated by the Q-switched envelope, and the Q-switched envelope ensures the output of high-energy laser pulses. By utilizing the Q-switched mode locking technology, one laser pulse can be decomposed into a plurality of pulses in the envelope without a delay light path, so that the separation of the laser pulse on a time sequence is realized, the energy of the mode locking pulse in the front edge of the Q-switched pulse envelope is lower, the energy is gradually increased before reaching a peak value, the ablation efficiency even exceeding the double-pulse laser ablation is realized, and the ablation effect is improved. At present, the pulse mode of laser used for ultraviolet laser atherosclerosis ablation is a pure Q-switched operation (QS), and besides the function of Q-switched operation, the QML pulse mode is used for atherosclerosis ablation to improve ablation efficiency and ablation effect. In addition, mode-locked pulse (ML) ablation provides a way to remove plaque without damaging the fibrous cap, thereby achieving subsurface ablation and volume reduction without plaque rupture. We therefore propose an atherosclerotic plaque ablation system with three pulsing modes QS, ML, QML. In the existing ultraviolet laser atheromatous plaque ablation, single-wavelength pulse laser is adopted for plaque ablation, for example 355nm solid laser applied to human plaque ablation can effectively treat calcified plaque by virtue of higher peak power, but has weak photochemical reaction with plaque tissues due to lower photon energy (3.5 eV), and has limited ablation capability on lipid plaque and fibrous plaque. The photon energy of the 266nm ultraviolet laser is higher (4.6 eV), so that the defect can be overcome, and the lipid plaque and the fiber plaque can be effectively treated. In addition, the absorption of 266nm in the contrast agent is better than 355nm, and the cavitation effect can be generated by interaction with the contrast agent, so that the requirements of different treatment scenes are met. But there is no QML laser that is compatible with both 266nm and 355 nm. Therefore, we propose to use the Q-switched mode-locked laser with 355nm and 266nm switching output function as the light source of the ultraviolet laser plaque ablation system to cope with different types of plaque tissues and improve ablation efficiency. Disclosure of Invention Therefore, the invention aims to provide a plaque ablation system based on a Q-switched mode locking technology, which is based on a Q-switched mode locking pulse laser and realizes high-energy Q-switched mode 355nm and 266nm laser output by combining a laser amplification technology with a nonlinear optical frequency conversion technology. In order to achieve the above purpose, the plaque ablation system based on the Q-switched mode locking technology provided by the invention comprises a Q-switched