Underwater sound visualization and temperature measurement using high-speed interferometer

[摘要] In this paper, we propose applying a high-speed polarization interferometer to underwater sound fields for their non-invasive visualization and temperature measurement. Underwater sound is usually measured by hydrophones that may disturb the sound field. To circumvent such disturbance, for airborne sound, a high-speed polarization interferometer has been proposed as a new measurement method. It enables non-contact measurement of non-stationary sound fields in air. This research applies the high-speed interferometer to underwater sound and confirms its capability of visualization. As an application, we also propose a non-invasive temperature measurement method that calculates temperature from the sound speed of visualized sound. As a result, we confirmed that the proposed method can measure the water temperature with an accuracy of about ±0.5 to 1.5°C.

[学科分类] 声学和超声波

[关键词] Parallel phase-shifting interferometry;Optical measurement;High-speed camera;Helmholtz equation;Spatial spectrum