An optical motion sensing device included a sensor frame defining an opening, a sensor pad disposed in the opening, an optical sensing system adapted to detect an amount of movement of the sensor pad in the sensor frame, and an output unit. The optical sensing system includes an optical waveguide, an...http://www.google.de/patents/US20090073461?utm_source=gb-gplus-sharePatent US20090073461 - Waveguide and Optical Motion Sensor Using Optical Power Modulation
