Proof of principle of a stokes polarimetry probe for skin lesion evaluation

This paper covers two proof of principle trials in an ongoing project to develop a fast, portable, and low-cost optical probe that uses Stokes polarimetry to evaluate skin lesions. Polarization is a property of light waves that describes the orientation and shape of their oscillations. The polarization state can be described using Stokes parameters, and several measurements derived from these parameters such as the degree of polarization, the azimuth and ellipticity angles of the polarization ellipse, and the coordinates on a Poincare sphere. The probe shines low-intensity polarization-controlled laser light at a lesion, and analyzes the backscattered light in order to detect how the light's polarization has been changed due to the light-tissue interaction. Testing with skin phantoms has demonstrated a relationship between phantom roughness and the degree of polarization. Preliminary testing on an in-vivo lesion showed that lesion sites demonstrated a lower degree of polarization as compared to normal skin. These results indicate our progress towards the development of a powerful and practical tool to assist skin lesion evaluation.