Experimental system of the full scattering profile of circular phantoms
Optical methods of sensing physiological tissue state base on light-tissue interaction are non-invasive, inexpensive and simplistic and therefore are very useful. Most of the optical methods are focused on the reflection light from the tissue, which is describes as a semi-infinite medium, while very few use the transmitted light.
We report, for the first time, an experimental observation of a typical reflected light intensity behavior for a circular structure characterized by the isobaric point. This method allows measuring in a single wavelength with no calibration. We suggest a new theoretically method for measuring the full scattering profile, which is the angular distribution of light intensity, of cylindrical tissues. Furthermore, we found an isobaric point, which is a central angle where the scattered light intensity does not dependence on the tissue's optical properties and linearly depends on the exact tissue geometry. We present that the experimental results match the simulation results. Furthermore, the experimental work present a new crossover point of the full scattering profiles of subjects with different diameters of the cylindrical tissues.
In addition, the blood vessels in human tissues are the main cause of light absorbing and also scattering. Therefore, the effect of blood vessels on light-tissue interactions is essential for biomedical applications based on optically sensing, such as oxygen saturation, blood perfusion and blood pressure. We present experimental measurements of the full scattering profile of heterogenic cylindrical phantoms which include blood vessels. We show the vessel diameter influence on the full scattering profile, and found higher reflection intensity for larger vessel diameters accordance to the shielding effect. These findings can be useful for biomedical applications such as non-invasive and simple diagnostic of the fingertip joint, ear lobe and pinched tissues.
* The work was carried out towards the M.Sc. degree in the Faculty of Engineering, Bar-Ilan University, with the supervision of Dr. Dror Fixler