Peculiarities of single-sided CW laser beam imaging of small-depth inhomogeneities in highly-scattering media

摘要

In this paper, we report some seemingly extraordinary features found experimentally and interpreted theoretically of images derived by optical sensing of small-depth characteristic inhomogeneities (inclusions, e.g. , ill places in tissues) in homogeneous highly-scattering host media (e.g. , healthy tissues), such as dilutions of Intralipid-20% emulsion in distilled water. It is shown experimentally that at a relatively small depth of the inhomogeneities, when they are not yet enveloped entirely by the scattering-widened laser beam, one may observe an inverted or/and double image of an inclusion, depending on the host-medium turbidity and on the inhomogeneity-to-host medium contrast. The effects observed result from some features of the intensity distribution of laser light backscattered from homogeneous liquid tissue-like phantoms of different turbidity. The results obtained would help one to develop optical (cw laser-beam assisted) diagnostics and tomography approaches and to solve the so-called specificity problem by unambiguous interpretation of the captured tissue images.