Design And Implementation Of Autofocus System Based On Scanning Acoustic Microscope

Acoustic scanning microscopy is an important branch of industrial testing and scientific research equipment.It is an important basic research technology and is widely used in many fields such as material analysis,biomedicine,and industrial quality.The resolution of current acoustic scanning microscope system has already reached the level of optical equipment.However,in the automatic focusing of the microscope,the technical adaptability is inadequate at home and abroad,which cannot meet the requirements of mainstream equipment,and becomes a problem that hinders the intelligentization of the acoustic scanning microscope equipment.It is meaningful to research and development the fast,accurate and widely-used autofocus technology.The dissertation mainly studies complete automatic focusing software which combines the motion control platform and ultrasonic focusing system.The major difficulty was the systematic integration of different discipline technologies,which should combine acoustic principles,digital signal processing,and mechanical control altogether.The dissertatio combines theoretical analysis,model building and practical application.It is hoped to realize the requirement of precise automatic focusing of the acoustic scanning microscope and verify the feasibility of the autofocus system through actual experiments and simulations.Due to the multidisciplinary approach,the dissertatio consists of several chapters illustrating the main content of the R&D process which includes autofocus acoustics to the building model,and combines actual signals to construct autofocus algorithms to mechanical motion control and optimization.The research work in the dissertatio was mainly divided into three parts:First,the sound source sound field was simLulated by multivariate Gaussian sound beam superposition method,and the sound source focus position was calculated by the simulation model.Combined with the parameters of-ultrasonic echo wave signal,acoustic wave transmission coefficient and acoustic wave attenuation,the autofocus process was comprehensively analyzed.Second,according to the principle of autofocus,the focus process formula was deduced and the focusing system was designed.The ultrasonic signal was processed in the acoustic scanning microscope and the V(z)curve was drawn by the optimized fast Fourier transform.Based on the parameters of the acoustic scanning microscope system,design technical indicators,and the system architecture diagram,the analysis and design of the autofocus system requirements will be achieved.Third,according to the motion system and control principle,the mathematical formula was derived to analyze the corresponding curve optimization parameters to meet the system design requirements,and the ultrasound system is used to solve the synchronization problem between the coordinate quantity and the ultrasonic quantity.The feedback data will be applied based on the acoustic principle to obtain the microscope sound scanning voltage timing diagram.Realize automatic focusing of each module and realize automatic focusing software with hardware.The acoustic scanning microscope designed by this system can successfully realize autofocus and meet the requirements of experimental precision.At the same time,the autofocus system was applied to the experimental platform to provide automatic focusing service for the acoustic sweep microscope experiment.