Cross-polarized backscatter in optical coherence tomography of biological tissue

We have observed that cross-polarized backscatter measured by optical coherence tomography of human skin In vivo is surprisingly strong. We identify and give evidence of its main origins: single scattering from nonspherical particles and multiple scattering by particles with sizes much larger than a wavelength. Our findings show that depolarized light scattered by dense large-diameter particles maintains a high degree of temporal coherence and that differential-polarization imaging improves contrast between particles of different sizes. (C) 1998 Optical Society of America OCIS codes: 170.0170, 260.5430, 030.1640, 290.4210.