Performance assessment of the SPDI subsurface imaging technique

Summary form only given.The ability of the spectral and polarization difference imaging (SPDI) technique to provide deep subsurface imaging in tissues is evaluated. The SPDI technique utilizes the wavelength dependence of the mean visit depth of photons inside a tissue sample before they emerge in the backscattered direction. Polarization filtering is used to discriminate against reflected photons from the superficial tissue layers. In addition, this technique involves subtraction of the perpendicular polarization image components obtained under polarized illumination at different wavelengths following appropriate adjustment of the time of exposure in order to normalize the number of photons backscattered from the outer tissue layers. This operation leads to a new image arising from photons that propagated deeper into the tissue which are contained in larger numbers in the image obtained using the longer illumination wavelength.