Patent ID: 8144339

Claim:
A positioning method by using optical speckles, comprising the steps of: a) selecting a point on a surface having unique textures as a reference point; b) partitioning the surface into a plurality of unit zones to form a two-dimensional zone array and setting location data for the unit zones with respect to the reference point; c) irradiating the surface with a highly coherent parallel light at an incident angle θ to produce scattered light beams and setting a sampling angle φ with respect to normal to the surface for obtaining a first optical speckle image formed by the scattered light beams in every unit zone at the sampling angle φ; d) establishing a look-up table containing the location data of each unit zone and corresponding first optical speckle image thereof; e) capturing a second optical speckle image of a detection point at the sampling angle φ; f) identifying the unit zone where the detection point is located, comprising: f1) inserting between two adjacent unit zones a dark zone, which can substantially transmit, absorb or reflect the highly coherent parallel light so that no scattered light beams are generated in the dark zone to form the first optical speckle image or the second optical speckle image, thereby forming a periodical energy change of optical speckles across the surface; and f2) counting number of peaks of optical speckle energy between the detection point and the reference point for identifying the unit zone where the detection point is located; and comparing the first optical speckle image in the unit zone where the detection point is located with the second optical speckle image for obtaining relative location of the detection point to the unit zone, and calculating location data of the detection point with respect to the reference point based on the relative location and location data of the unit zone where the detection point is located.