Night vision systems in vehicles are a new emerging technology. A crucial problem in active (laser-based) systems is distortion of images by saturation and blooming due to strong retroreflections from road signs. We quantify this phenomenon. We measure the Mueller matrices and the polarization state of the reflected light from three different types of road sign commonly used. Measurements of the reflected intensity are also taken with respect to the angle of reflection. We find that different types of sign have different reflection properties. It is concluded that the optimal solution for attenuating the retroreflected intensity is using a linear polarized light source and a linear polarizer with perpendicular orientation (with regard to the source) at the detector. Unfortunately, while this solution performs well for two types of road sign, it is less efficient for the third sign type.
© 2008 Optical Society of America
Original Manuscript: March 13, 2008
Revised Manuscript: May 30, 2008
Manuscript Accepted: June 26, 2008
Published: July 23, 2008
Aviran Halstuch and Yitzhak Yitzhaky, "Properties of light reflected from road signs in active imaging," Appl. Opt. 47, 4031-4036 (2008)