Depth selectivity in biological tissues by polarization analysis of backscattered light

International audienceDepth selectivity is crucial for accurate depth volume probing in vivo in a large number of medical applications such as brain monitoring. Polarization gating has been widely used to analyze biological tissues. It is shown that using polarized light allows probing tissues on a specific depth depending on the polarization illumination type (linearly, circularly) and the tissues properties. However, accurate depth investigation of the tissue requires a high selectivity of the probed depth. We propose and simulate the use of different elliptically polarized illuminations for continuous depth examination between linearly and circularly polarized illumination. Monte Carlo simulations verify that circularly polarized illumination penetrates deeper than linearly polarized illumination in biological scattering media. Furthermore, we show that elliptically polarized light can be tuned in its penetration depth continuously between the penetration depth of linearly polarized light and circularly polarized light. Experimental results obtained on phantoms mimicking in vivo situations are presented