Device and method for determining movement

摘要

A high resolution device for determing movement of a surface relative to a detector, the detector comprises a coherent source of radiation 2 eg. a laser directed at the surface 8 or a ball in contact therewith, and a plurality of radiation sensors 3 arranged to detect an intensity pattern eg. laser speckle pattern due to interference in the radiation reflected back from the surface. Outputs from the sensors are repeatedly sampled or continuously monitored and comparison means is used to calculate spatial and temporal intensity gradients between adjacent sensors to determine the successive displacement of the pattern. The device has particular use in a mouse or tracker ball for computer input, or in a digital microphone.