Coherent backscattering in biological media: measurement and estimation of optical properties.

We measured the coherent backscattering of light from milk solutions and biological tissues by using a He-Ne laser (633 nm) and a CCD array as a detector. A coherent peak from the milk solutions could bemeasured with a single exposure. However, ensemble averaging was required for coherent peaks to be produced from solid media such as tissue samples. By fitting experimental data to an existing model numerically, effective scattering and absorption coefficients were estimated. They were compared with those computed from integrating sphere measurements. Effective scattering coefficients computed by the two different methods were in good agreement for high-scattering media. However, higher absorption was estimated by the coherent peak method.