Acousto-Optic Imaging in Perspective

Date: Sunday, April 9, 2006

Presented by

Albert Claude Boccara, PhD

Abstract

Revealing an optical contrast linked to the local scattering or absorption with a sufficient resolution of a structure deeply buried in biological tissues is difficult. Indeed the purely optical inverse problem remains extremely complex due to the heterogeneity of the optical properties of biological tissues. In the case of breast imaging, it is not possible at this time to spatially resolve tumors of diameter less than roughly one cm.

Acousto-optic imaging aims at overcoming this limitation by “tagging” the photons along their paths by a localized ultrasound irradiation: the sample (tissue) under study is illuminated by a single frequency laser beam of very long coherence length, and also insonified by a focused ultrasound beam in order to periodically modify the phase of the optical waves in the focal zone of the ultrasound beam.

This approach intends to reveal optical contrasts with a spatial resolution linked to the acoustic resolution (1mm3). Nevertheless even if experimental validations have been done some on tissue phantoms difficulties still remain for in vivo applications. We will discuss few experimental schemes able to optimize the signal to noise ratio and to avoid low frequency noises and high frequency decorrelation by blood flow.

Joint work with Francois Ramaz, Benoit Forget, Michel Gross, Emmanuel Bossy.

Speaker Biography

Dr. Albert Claude Boccara is Professor of Optics and Dean of Research at the Ecole Superieure de Physique et Chimie Industrielles of the City of Paris. This research center, headed until recently by Pierre-Gilles de Gennes (Nobel Price in Physics) includes twenty laboratories active in the fields of Physics, Chemistry and Biology and linked to the National Center for Scientific Research. After obtaining his PhD in Physics (solid state spectroscopy), Dr. Boccara visited several US universities in Los Angeles, Berkeley and Detroit. His main interest is to push optical measurements at their physical limits in various fields: polarized light imaging and spectroscopy, photothermal imaging, optical detection of gravitational waves, near field imaging of nanostructures and, more recently, imaging though scattering media for biomedical applications.