A Noninvasive Optical Technique For Characterizing The Normal Acoustic Modes Of A Water Tank
Abstract
In order to characterize and develop underwater acoustic sensors, researchers are often forced to choose between using portable calibrators (restricted size), dedicated acoustic testing facilities (costly, restricted access), or using water tanks with unknown acoustic properties. Additionally, analytic methods often fall short in predicting the acoustic properties of tanks with unknown geometries, material properties, and boundary conditions. To address these limitations, we propose and demonstrate an optical technique to efficiently and noninvasively calibrate the normal modes of an arbitrary water tank with partially reverberant boundary conditions. The technique relies on measuring the integrated optical phase change introduced by the acoustic induced change in the refractive index of water. In this work, we use this approach to find the fundamental mode of a large oval water tank at two water depths and validate the optical measurements using conventional hydrophones. By enabling the rapid and non-invasive characterization of the normal acoustic modes of an arbitrary water tank, this technique enables a wide range of custom designed water tanks to be used for underwater acoustic experiments.
Document Details
- Document Type
- Technical Report
- Publication Date
- May 07, 2018
- Accession Number
- AD1055403
Entities
People
- Allen P. Davis
- Brandon Redding
- Matthew Pittman
- Sean Krupa
Organizations
- United States Naval Research Laboratory