3-DIMENSIONAL SOUND PRESSURE FIELD MEASUREMENT USING PHOTOELASTIC COMPUTER-TOMOGRAPHY METHOD

A photoelastic computer tomography method is developed to determine th e three-dimensional sound pressure distribution of a longitudinal wave . An acoustic wave emitted from a probe gives a three-dimensional soun d pressure distribution that depends on the ultrasonic transducer used . Since thee sound pressure distribution affects the results of the ul trasonic measurements, the authors have experimentally studied the sou nd pressure distribution using a photoelastic ultrasonic visualization system. Hence we have developed a highly sensitive visualization syst em for the quantitative measurement of a weak emitted wave. However. s ince this method utilizes photoelasticity, the estimated sound field i s limited to a two-dimensional one. In this study, the basic measureme nt system and the analysis algorithm for ultrasonic visualization have been improved to measure the three-dimensional propagation in solids using the computer tomography technique based on the two-dimensional p hotoelastic ultrasonic visualization technique. Using this system: thr ee-dimensional sound pressure distribution of a commercial probe in th e near field and/or far field are measured and compared with the resul ts of the theoretical estimations.