Design Of Accurate Detection System Of Shock Wave Energy Based On Acousto-optic Diffraction

Shockwave is a kind of sound wave with special properties,which is originally applied to the field of extracorporeal lithotripsy.In the 1980s,the shockwave technology was applied to the clinical trials,which opened a new chapter of physical medicine.Since different diseases and treatment sites require different treatment options,it is necessary to adjust the excitation pressure of the medical shock wave,the probe model,the excitation frequency and other parameters.Therefore,the limitations of the treatment parameters adjusted according to the doctor’s experience and patient feedback are significant.The energy flow density of shock wave is directly related to the treatment effect,which is the premise and foundation of customized accurate treatment.According to the principle,the shock wave detection method can be divided into a hydrophone method,a pulse echo method,a radiation force balance method,and an optical diffraction and interference method.Among them,the pulse echo method and the radiation force balance method are only applicable to the acoustic signal detection of a single frequency,and do not conform to the characteristics of the shock wave;and the hydrophone method will cause interference to the sound field,and long-term shock wave detection will cause irreversible damage to the hydrophone.In this paper,the Raman-Nath diffraction is selected as the detection principle,and the non-contact method is adopted to measure the energy flow density of the divergent shock wave.The main work of this paper is divided into the following parts:1.This paper proposes the energy density as the evaluation standard of shock wave treatment,and takes the acousto-optic diffraction as the detection principle.Besides,the feasibility of using Raman-Nath diffraction as the principle of extracorporeal shock wave energy detection is verified and the calculation formula of energy flow density is deduced,and the difficulty of the detection of divergent shock wave energy compared to the detection of focused shock wave energy;2.This paper analyzes the system parameters based on the detection requirements,and completes the hardware and software design of the detection system.The hardware design mainly includes the experimental platform construction,the selection of laser and photoelectric sensor,the design of signal acquisition;and the software design includes two parts:the design of measurement and control program based on Lab VIEW and the design of data processing program based on MATLAB.Besides,an accurate detection system for shock wave energy based on acousto-optic diffraction method is established,where the system sampling rate is 2MHz,the spatial resolution is up to 0.1mm,and the detection accuracy of energy density is higher than0.001m J/mm~2.3.This paper compares the energy detection results of the ultrasonic power meter in metrology institute and the system of this paper,and verifies the feasibility of the detection system.The performance of the focused and planar ultrasonic transducers was measured using the detection system.In this paper,the diffracted light intensity waveform is drawn and the corresponding energy flow density is calculated,and the performance of the detection system is analyzed.4.In this paper,based on the acousto-optic diffraction system,the energy density of the divergent shock wave therapy device is measured,and the influences and causes of one or more variables of the excitation pressure,the excitation frequency,the probe type and the distance between the probe and the laser(the distance between the probe and the affected area)on energy are analyzed.This paper provides a reference for the manufacture and energy calibration of the divergent shock wave therapy device,which is of great significance for the accurate treatment of extracorporeal shock wave.