A miniaturized multidirectional optical motion sensor and input device based on laser self-mixing

Using the laser self-mixing effect, a miniaturized two-dimensional motion sensor has been developed that works on almost any light-scattering surface. By applying the sensor to the surface of a finger, for example, an input device (scroll, click) can be built for hand-held applications. A three-dimensional input device (x, y, click), which will be presented soon, is based on the principles explained in this paper. We also present the physical and technological challenges and the solutions required to build a practical, miniaturized and robust device.