US Patent 9086738 Multi-surface optical tracking system

An optical tracking device that is capable of operation on both glossy and diffuse surfaces includes at least one housing, at least one light source, and at least one sensor. The light source emits light toward a surface on which the housing is moved and the sensor receives the light emitted by the light source after it is reflected off of the surface. The light source is oriented such that the angle of incidence of the emitted light corresponds to Brewster's angle. The sensor may be also oriented such that the angle of reflection of the reflected light corresponds to Brewster's angle. The light emitted by the light source may be polarized to increase the p-polarization of the emitted light and/or the light received by the sensor may be filtered to block s-polarized portions of the reflected light.