Patent ID: 7126586
Filing Date: 2006-10-24
Classification: G01P,G06F

Abstract:
1. A data input device for use with a tracking surface, said tracking surface having light-scattering properties with respect to said device, said device comprising: a single laser having a cavity from which a light beam is projected; a light beam modulator for modulating the frequency of the light beam over time; a beam splitter for splitting the modulated light beam into a first modulated light beam and a second modulated light beam; said beam splitter being configured to project the first modulated light beam onto said tracking surface along a first light path, at least a portion of the first modulated light beam striking said tracking surface and reflecting back into the cavity of said laser along said first light path and thereby altering at least one first characteristic of the projected modulated light beam, said beam splitter further being configured to project the second modulated light beam onto said tracking surface along a second light path, at least a portion of the second modulated light beam striking said tracking surface and reflecting back into the cavity of said laser along said second light path and thereby altering at least one second characteristic of the projected modulated light beam; a detector associated with the laser for detecting said altered first and second characteristics of the modulated light beam projected by the laser; and a controller responsive to the detector for determining the relative movement of the tracking surface and data input device relative to one another as a function of the altered first and second characteristics detected by the detector.