Spatial localization of absorbing zones in a turbid media using NIR CW lasers

The problem of spatial localization of a near-infrared (NIR) light absorber in turbid media is approached using continuous wave (CW) laser diode sources. The excitation and backscattered light are fiber optic guided. It is a preliminary study for the development of simple and portable optical instrumentation concerning quantitative non invasive oxymetry. A stable, not expensive, well defined and reproducibile phantom to test the performances of NIR spectroscopy instrumentation is presented. lntralipid solution is used as turbid medium. The concentration of Intralipid is chosen to match the "in-vivo" optical coefficients. The size distribution of scattering particle are actually determined by a laser light-scattering analyzer. A moving absorber driven by a micrometer positioning system is placed inside the turbid medium. A NIR CW laser diode oxymeter with fiber optic probe is tested with the system. Several measurements are presented at differem source-detector distances, absorber positions and lntralipid concentrations. The maximum inspection depth (MID) is defined and measured for the instrument under test.