Hamburg 2001 – wissenschaftliches Programm

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DY: Dynamik und Statistische Physik

DY 46: Poster

DY 46.1: Poster

Donnerstag, 29. März 2001, 15:45–18:15, Foyer S\ 3

Imaging of spatially heterogeneous turbid media using the 3D cross correlation scheme — •Ronny Vavrin, Frank Scheffold, and Peter Schurtenberger — Departement für Physik, Universität Freiburg, CH-1700 Freiburg

In recent years considerable attention has been paid to the development of biomedical imaging techniques using visible light. Optical imaging of biological tissues may provide different advantages: it is save, non-evasive and can be set up at a relative low cost. Near-infrared light is the least absorbed radiation in human tissue with an absorption length of typically 0.1-1cm. The limiting factor for the efficiency of optical imaging is the strong multiple scattering of biological tissues, which reduces resolution and penetration depth. In this study we use the novel 3-D light scattering technique to image singly scattered photons in a turbid medium. The 3D-cross correlation scheme uses two crossing laser beams that define a scattering volume (cross section approx. 100 micron) which can be moved in three dimensions. By cross-correlating the scattered intensity from the two beams, multiply scattered photons are filtered out efficiently. The applicability of the method is investigated by scanning a rectangular cell with an embedded capillary containing colloidal suspensions with different optical properties. Our measurements show that using the 3-D technique it is possible to image three dimensional optical density variations with a resolution of approximately 200 micron and a penetration depth of at least 2-3 scattering mean free paths of the outer medium.