A presence of a polarization altering substance on a specular surface is detected by transmitting light from a single strobed light source to the surface over a transmitting path and receiving the transmitted light from the surface. An intensity of the light is measured in both an optical non-isolator...http://www.google.fr/patents/US6069565?utm_source=gb-gplus-shareBrevet US6069565 - System for detecting ice or snow on surface which specularly reflects light
System for detecting ice or snow on surface which specularly reflects light
