Study On Ultrasonic Power Measurement Technology Based On Acousto-optic Effect

Ultrasound is widely used in many fields including medical,military,and chemical because of its special physical properties.Ultrasonic power measurement technology has been studied in order to achieve precise control of ultrasonic waves and to avoid application problems caused by high uncertainties.In this thesis,an ultrasonic power measurement method based on the principle of acousto-optic effect is studied,and the optical platform and measurement software of ultrasonic power measurement are designed.Firstly,the thesis elaborates on the characteristics and application of ultrasonic,and puts forward the significance of ultrasonic power measurement.At the same time,it expounds and analyzes the research status of related power measurement technology at home and abroad,and proposes the basic research ideas of measurement system based on acousto-optic effect method.Secondly,according to the principle of acousto-optic effect and schlieren imaging technology,the design and construction of ultrasonic power measurement system based on acousto-optic effect is completed.The principle of acousto-optic power measurement technology and the schlieren system are analyzed in detail.The feasibility of power measurement based on acousto-optic method is verified.At the same time,the optical path system of acousto-optic measurement platform is designed according to the measurement principle.The He-Ne laser is selected as the light source,and the laser is further processed by a beam expander,a filter,etc.,and then the laser passes through the ultrasonic grating to form a diffraction fringe,which is focused by an convex lens,and is collected by a CCD camera and then introduced into a computer for analysis of diffraction intensity.Then the construction of the acousto-optic ultrasonic power measurement platform is completed.Thirdly,based on the principle of acousto-optic power measurement,an image processing software for diffraction spots is designed and written.The functions that the software needs to implement include adjusting the exposure value and white balance of the CCD camera,and performing image processing operations such as graying,binarization,edge detection,and calculation of relative light intensity on the diffracted pattern.According to the corresponding function,the code of the image processing operation is integrated.At the same time,the image processing algorithm in the key part of the measurement software is optimized,including threshold selection,calculation of additional phase shift,and division of the spot area.Then,the design of the measurement software is completed.Finally,the acousto-optic ultrasonic power measurement system and the radiation force balance power measurement instrument are compared to complete the reliability verification of the acousto-optic measurement system.The ultrasonic power measurement system based on the acousto-optic effect in the thesis is used to measure the power of the same ultrasonic source with the current ultrasonic power measurement equipment based on the radiation force balance method.The measurement data is analyzed and processed by the En value method to verify the accuracy and scientificity of the acousto-optic measurement system.