Spectral degree of linear polarization of light from healthy skin and melanoma.

A non-invasive optical technique, based on a supercontinuum laser source and hyperspectral sensors, is established to measure the spectral degree of linear polarization (DOLP) in a broad spectral range from 525 nm to 1000 nm. Several biomaterials of interest, such as healthy and cancerous skins, are considered. The spectral DOLP of melanoma, from 5 mm to 9 mm diameter, are measured and analyzed. An increase of the spectral DOLP is reported for 100% of the melanoma samples compared to healthy skin samples. The spectral DOLP of a given melanoma appears to be correlated to the stage of its development: the larger the melanoma, the higher the DOLP. Such trend could be explained by a decrease of the surface roughness along the evolution of the disease. In addition, a significant spectral dependence of the DOLP is reported for melanoma samples as it exhibits a decrease in the near infrared from 750 nm to 1000 nm.