Improved performance in diffuse reflectance measurement by polarization discrimination

Previous research has shown that un-contact monitoring and characterization of diffuse reflectance photons emerged at the tissue surface could provide the useful physiological parameters within tissue to aid the diagnosis. Generally within this method, the detected optical signal consists of the specular reflection from the tissue surface and diffusive photons emerging from within tissue, while the latter being the signal of interest. However, the surface reflection signal would degrade the signal-to-noise ratio of the system. Therefore, there is a need to eliminate the effect of specular reflection having on the final measurement. In this paper, a simple method using polarization and cross-polarization pair is presented to improve the system SNR by efficiently removing the surface specular reflection. We are expecting that this simple technique could play an important role in the blood glucose measurement with the NIR approach.