A tomographic visualization of sound fields using laser diffraction

Abstract

In this study, we propose a method for non-contact visualization of sound fields, generated by an ultrasonic transducer, with the use of laser diffraction.The fundamental operational principle is based on optical computerized tomography(CT).The reconstructed, two-dimensional images are the amplitude and the phase distributions of the sound fields.In order to acquire this information of the sound fields, we used a laser beam as an optical probe.The laser beam passed through a sound field perpendicular to the sound beam and was detected without any optical system by a photodiode on the opposite side.In our experiment, we used a circular transducer driven at a frequency of 1.412MHz for a sound source.The experimental results were approximately in agreement with the results we obtained by measuring with a hydrophone.