Frankfurt 2006 – scientific programme
Parts | Days | Selection | Search | Downloads | Help
Q: Quantenoptik und Photonik
Q 36: Poster Photonik in komplexen und periodischen Strukturen
Q 36.1: Poster
Tuesday, March 14, 2006, 16:30–18:30, Labsaal
Diffusing-wave spectroscopy from multilayer media with non-scattering inclusions — •T. Gisler, F. Jaillon, J. Li, G. Maret, and G. Dietsche — Universität Konstanz, Fachbereich Physik, Fach M621, 78457 Konstanz
Dynamic multiple light scattering (diffusing-wave spectroscopy - DWS) is emerging as a new tool for non-invasive biomedical diagnosis, as it is a marker-free method which is very sensitive to microscopic displacement of scatterers within tissue. Recently DWS has been used to detect activation of the human brain fully non-invasively through intact scalp and skull (T. Durduran et al., Opt. Lett. 29, 1766-1768 (2004); J. Li et al., J. Biomed. Opt. 10, 044002 (2005)). These experiments have raised the question about the validity of the diffusion approximation for the description of the measured temporal field autocorrelation function g(1)(τ) when a non-scattering layer such as the cerebrospinal fluid (CSF) is present.
In this contribution we present experimental results from a 3-layer tissue phantom with calibrated optical and dynamic properties. Field autocorrelation functions g(1)(τ) measured in backscattering geometry with source and receiver at a distance of 1-4 cm are found to agree well with predictions from correlation-diffusion theory if the presence of the non-scattering layer is accounted for by a distance-dependent modification of the boundary conditions between non-scattering and turbid layers. Experiments and theory also agree well with multilayer Monte-Carlo simulations of g(1)(τ).