Share Email Print

Proceedings Paper

Integration of a laser doppler vibrometer and adaptive optics system for acoustic-optical detection in the presence of random water wave distortions
Author(s): Phillip Land; Dennis Robinson; James Roeder; Dean Cook; Arun K. Majumdar
Format Member Price Non-Member Price
PDF $17.00 $21.00

Paper Abstract

A new technique has been developed for improving the Signal-to-Noise Ratio (SNR) of underwater acoustic signals measured above the water’s surface. This technique uses a Laser Doppler Vibrometer (LDV) and an Adaptive Optics (AO) system (consisting of a fast steering mirror, deformable mirror, and Shack-Hartmann Wavefront Sensor) for mitigating the effect of surface water distortions encountered while remotely recording underwater acoustic signals. The LDV is used to perform non-contact vibration measurements of a surface via a two beam laser interferometer. We have demonstrated the feasibility of this technique to overcome water distortions artificially generated on the surface of the water in a laboratory tank. In this setup, the LDV beam penetrates the surface of the water and travels down to be reflected off a submerged acoustic transducer. The reflected or returned beam is then recorded by the LDV as a vibration wave measurement. The LDV extracts the acoustic wave information while the AO mitigates the water surface distortions, increasing the overall SNR. The AO system records the Strehl ratio, which is a measure of the quality of optical image formation. In a perfect optical system the Strehl ratio is unity, however realistic systems with imperfections have Strehl ratios below one. The operation of the AO control system in open-loop and closed-loop configurations demonstrates the utility of the AO-based LDV for many applications.

Paper Details

Date Published: 17 May 2016
PDF: 13 pages
Proc. SPIE 9827, Ocean Sensing and Monitoring VIII, 982702 (17 May 2016); doi: 10.1117/12.2229300
Show Author Affiliations
Phillip Land, Naval Air Warfare Ctr. Weapons Div. (United States)
Dennis Robinson, Naval Air Warfare Ctr. Weapons Div. (United States)
James Roeder, Naval Air Warfare Ctr. Weapons Div. (United States)
Dean Cook, Naval Air Warfare Ctr. Weapons Div. (United States)
Arun K. Majumdar, Naval Air Warfare Ctr. Weapons Div. (United States)

Published in SPIE Proceedings Vol. 9827:
Ocean Sensing and Monitoring VIII
Weilin W. Hou; Robert A. Arnone, Editor(s)

© SPIE. Terms of Use
Back to Top
Sign in to read the full article
Create a free SPIE account to get access to
premium articles and original research
Forgot your username?