Robust technique of analyzing and locating laser speckle patterns for optical computer mice

Laser speckles have been used in measurement techniques, since they were discovered to be correlated with the displacement of the light source. This paper presents a robust technique of analyzing and locating laser speckle patterns (LSPs) for a prototype of a laser optical mouse. After the speckle images are captured from the image-grabbing device, they are analyzed by the proposed image processing procedures and normalized cross-correlation (NCC) is adopted to develop position-locating rules for laser speckle patterns. To verify robustness of the proposed approach, nine different materials of mouse pad are used. Experimental results show that they have all achieved similar and promising performance. Therefore, the proposed technique can not only precisely calculate the moving directions and displacement information for laser speckles, the linearity for the prototype of laser mouse can also be verified.