Patent ID: 7459671

Claim:
An optical sensor for sensing relative movement between the sensor and a surface by detecting changes in optical features in a pattern of light reflected from the surface, the sensor including a two dimensional (2D) array of photosensitive elements comprising at least: a first plurality of photosensitive elements arranged and coupled to select a 2D spatial frequency of the pattern created by light reflected from the surface and to generate in response thereto a first signal which is a function of movements along a first set of at least two non-parallel axes by algebraically combining outputs from each of the first plurality of photosensitive elements; and a second plurality of photosensitive elements arranged and coupled to select a 2D spatial frequency of the pattern created by light reflected from the surface and to generate in response thereto a second signal which is a function of movements along a second set of at least two non-parallel axes by algebraically combining outputs from each of the second plurality of photosensitive elements.