Form-biattenuance (Δχ) in biological tissue arises from anisotropic light scattering by regularly oriented cylindrical fibers and results in a differential attenuation (diattenuation) of light amplitudes polarized parallel and perpendicular to the fiber axis (eigenpolarizations). Form-biattenuance is complimentary to form-birefringence (Δn) which results in a differential delay (phase retardation) between eigenpolarizations. We justify the terminology and motivate the theoretical basis for form-biattenuance in depth-resolved polarimetry. A technique to noninvasively and accurately quantify form-biattenuance which employs a polarization-sensitive optical coherence tomography (PS-OCT) instrument in combination with an enhanced sensitivity algorithm is demonstrated on ex vivo rat tail tendon (mean Δχ=5.3·10-4, N=111), rat Achilles tendon (Δχ=1.3·10-4, N=45), chicken drumstick tendon (Δχ=2.1·10-4, N=57), and in vivo primate retinal nerve fiber layer (Δχ=0.18·10-4, N=6). A physical model is formulated to calculate the contributions of Δχ and Δn to polarimetric transformations in anisotropic media.
© 2005 Optical Society of America
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