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Proceedings Paper

Optical measurement of sound using time-varying laser speckle patterns
Author(s): Terence S. Leung; Shihong Jiang; Jeremy Hebden
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Paper Abstract

In this work, we introduce an optical technique to measure sound. The technique involves pointing a coherent pulsed laser beam on the surface of the measurement site and capturing the time-varying speckle patterns using a CCD camera. Sound manifests itself as vibrations on the surface which induce a periodic translation of the speckle pattern over time. Using a parallel speckle detection scheme, the dynamics of the time-varying speckle patterns can be captured and processed to produce spectral information of the sound. One potential clinical application is to measure pathological sounds from the brain as a screening test. We performed experiments to demonstrate the principle of the detection scheme using head phantoms. The results show that the detection scheme can measure the spectra of single frequency sounds between 100 and 2000 Hz. The detection scheme worked equally well in both a flat geometry and an anatomical head geometry. However, the current detection scheme is too slow for use in living biological tissues which has a decorrelation time of a few milliseconds. Further improvements have been suggested.

Paper Details

Date Published: 17 February 2011
PDF: 6 pages
Proc. SPIE 7896, Optical Tomography and Spectroscopy of Tissue IX, 789623 (17 February 2011); doi: 10.1117/12.874707
Show Author Affiliations
Terence S. Leung, Univ. College London (United Kingdom)
Shihong Jiang, Univ. College London (United Kingdom)
Jeremy Hebden, Univ. College London (United Kingdom)

Published in SPIE Proceedings Vol. 7896:
Optical Tomography and Spectroscopy of Tissue IX
Bruce Jason Tromberg; Arjun G. Yodh; Mamoru Tamura; Eva Marie Sevick-Muraca; Robert R. Alfano, Editor(s)

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