| The Tm:YAG laser with a wavelength between 1.9 and 2.1 μm can be strongly absorbed by the water in the tissue of the human lesion,so as to interact with the tissue and achieve the purpose of treatment,making it widely used in the medical field.Tm:YAG lasers not only have obvious advantages in medical diagnosis and treatment,but also have extensive applications in other fields.For example,the Tm:YAG laser with a wavelength of 2 μm is also widely available in a series of fields such as lidar and ranging,etc.and also has very significant advantages and application prospects.Laser lithotripsy is a typical application of the 2 μm band laser in the medical field.The main mechanism of laser lithotripsy is to use a pulsed laser with a wavelength of 2μm to be absorbed by water in and near the surface of the stone tissue and vaporize and expand to crush the stone.At present,the holmium laser is widely used in the treatment of lithotripsy in urology.The general laser pulse width is 200～400 μs and the pulse energy is 1～3 J.Because the repetition frequency of the holmium laser output is not high,the single pulse energy is large,and there is a large impact in the operation.The pulsed thulium laser recently developed by IPG Russia can achieve a high repetition frequency output of 1 KHz and a single pulse energy of 0.2 J,which has a better effect in lithotripsy applications.The current research on laser lithotripsy is mainly to use existing lasers for lithotripsy experiments,but the laser parameters such as peak power,pulse width and repetition frequency are limited by specific lasers,and it is not easy to find the most ideal effect.Therefore,studying the mechanism and physical process of laser lithotripsy has important practical application value for optimizing the parameters of laser lithotripsy and guiding the development of laser lithotripsy surgery.This article analyzes the relevant key technologies in the Tm:YAG laser lithotripsy system for Tm:YAG laser lithotripsy.Firstly,it introduces common minimally invasive surgical methods used in clinical surgery,focusing on the mechanism of holmium laser lithotripsy and related technologies in laser lithotripsy.Starting from the analysis of thulium laser lithotripsy that can replace holmium laser,combined with the introduction of IPG The new pulsed thulium laser lithotripsy system,analyzing high-frequency pulses in the lithotripsy process may have better clinical effects.The Euler method was used to establish a numerical model of thermally induced micro-explosion of water near the stone surface under laser radiation,calculate the change process of physical parameters such as the impact pressure on the surface of the stone tissue during the micro-explosion,and analyze the mechanism and optimal fragmentation of thulium laser lithotripsy Stone laser parameters.The calculation results show that increasing the pulse width,multiple pulses and reducing the distance between the end face of the optical fiber and the surface of the biological hard tissue within a certain range can increase the impact pressure of the microburst on the surface of the tissue.In addition,the paper introduces some laser parameter setting and control technology in the laser lithotripsy system,and analyzes the advantages and feasibility of the Tm:YAG laser in the lithotripsy system based on the theoretical knowledge of electro-optic Q modulation and the laser pulse characteristic obtained by using electro-optic Q modulation. |
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