The Theory Behind the Full Scattering Profile

Optical methods for extracting properties of tissues are commonly used. These methods are non-invasive, cause no harm to the patient and are characterized by high speed. The human tissue is a turbid media hence it poses a challenge for the different optical methods. In addition the analysis of the emitted light requires calibration for achieving accuracy information. Most of the methods analyze the reflected light based on their phase and amplitude or the transmitted light.

We suggest a new nanophotonic method for extracting optical properties of cylindrical tissues based on their full scattering profile (FSP), which mean the angular distribution of the reemitted light. The propagation path of each photon was calculated from the scattering constant and the scattering was measured experimentally. The FSP of cylindrical tissues is relevant for biomedical measurement of fingers, earlobes or pinched tissues. We found the iso-pathlength (IPL) point, a point on the surface of the cylinder medium where the light intensity remains constant and does not depend on the reduced scattering coefficient of the medium, but rather depends on the spatial structure and the cylindrical geometry. However, a similar behavior was also previously reported in reflection from a semi-infinite medium. Moreover, we presented a linear dependency between the radius of the tissue and the point`s location. This point can be used as a self-calibration point and thus improve the accuracy of optical tissue measurements. This natural phenomenon has not been investigated before. We show this phenomenon theoretically, based on the diffusion theory, which is supported by our simulation results using Monte Carlo simulation, as well as experimental results with phantoms and real fingers.