Patent ID: 8164569

Claim:
An optical navigation input device comprising: a light source to direct a light beam toward a substantially specular illumination surface to illuminate a primary illumination spot at the illumination surface, wherein the light beam reflects off of the illumination surface along a specular reflection path, and scattered light reflects off of a surface reflection feature along a scattered light path which is offset from the specular reflection path; an illumination aperture structure to at least partially define an illumination aperture interposed between the light source and the illumination surface, the illumination aperture to produce a diffraction pattern relative to the light beam, wherein the diffraction pattern comprises a diffraction discontinuity which is substantially free from diffracted light within a sector area outside of the light beam; and an image sensor disposed within the scattered light path at a location corresponding to the diffraction discontinuity, wherein the image sensor is configured to receive the scattered light from the surface reflection feature and to generate a navigation image of the surface reflection feature.