Patent ID: 8576402

Claim:
A system for optical navigation, the system comprising: a light source to illuminate a navigation surface, wherein the navigation surface reflects light from the light source; and an imaging system located approximately within a path of the reflected light, the imaging system comprising: a lens to receive the reflected light from the navigation surface, wherein the lens is configured to focus a specular portion of the reflected light to a focus region; a mask at approximately the focus region, the mask configured to filter out substantially all of the specular portion of the reflected light and pass at least some of a scattered portion of the reflected light outside of the focus region, wherein the mask is located within 1 mm of the focus region, and wherein the focus region is located on a plane at which the cross section of the specular portion of the reflected light is minimal; and an image sensor to generate a navigation signal based on the scattered portion of the reflected light that passes outside the focus region and is incident on the image sensor.