OPTICAL INPUT DEVICE BASED ON DOPPLER SHIFT AND LASER SELF-MIXING

摘要

In an optical input device based on movement of an object ( 15 ) and the device relative to each other and which comprising at least one optical sensor unit including a laser ( 3 ) having a laser cavity for generating a measuring beam ( 13 ), converging means ( 50 ) for converging the measuring beam in an action plane and for converging measuring beam radiation reflected by the object in the laser cavity to generate a self-mixing effect in the laser and measuring means for measuring the result of the self-mixing effect, which effect is determined by said movement, the converging means ( 50 ) is adapted to provide a self-mixing effect that is smaller than a possible maximum but larger than a detection threshold for an extended range of distances (DeltaZ) between the object and the device. This allows obtaining the required self-mixing effect in an extended range of distances between the object and the device.