Patent ID: 7285766

Claim:
An optical displacement sensor for sensing relative movement between a data input device and a surface by determining displacement of optical features in a succession of frames, the sensor comprising: an illuminator having a light source configured to originate an illumination beam and illumination optics configured to transform the illumination beam to a non-circular shape and further configured to illuminate a non-circular portion of the surface by the non-circular-shaped illumination beam, wherein the non-circular-shaped illumination beam has a substantially planar phase-front; and a detector having a plurality of photosensitive elements in a non-circular arrangement and imaging optics configured to receive non-circular-shaped illumination reflected from the surface and to image the reflected non-circular-shaped illumination onto the non-circular arrangement of photosensitive elements, wherein the plurality of photosensitive elements includes a first plurality of photosensitive elements arranged in substantially straight line along a first axis, and a second plurality of photosensitive elements arranged in substantially straight line along a second axis, and wherein the second axis is non-parallel to the first axis.