Patent ID: 7566863

Claim:
An optical encoder comprising: a light source configured to generate a beam of light along an original propagating direction; an encoder member positioned to receive said beam of light from said light source, said encoder member including a digital diffractive optic track, and first and second tracks, said digital diffractive optic track being configured to optically manipulate said beam of light into a particular combination of manipulated beams of light from a plurality of combinations of manipulated beams of light as said encoder member is displaced with respect to said light source, each of said combinations of manipulated beams of light representing a position of said beam of light on said digital diffractive optic track, said first track including a plurality of first digital diffractive optic regions, each of said first digital diffractive optic regions being separated from adjacent first digital diffractive optic regions by some distance, each of said first digital diffractive optic regions being configured to optically manipulate said beam of light from said original propagating direction to a first modified propagating direction, said second track including a plurality of second digital diffractive optic regions, each of said second digital diffractive optic regions being separated from adjacent second digital diffractive optic regions by some distance, each of said second digital diffractive optic regions being configured to optically manipulate said beam of light from said original propagating direction to a second modified propagating direction, wherein said first and second digital diffractive optic regions are positioned on said encoder member such that said first digital diffractive optic regions are offset with respect to said second digital diffractive optic regions such that said first digital diffractive optic regions are offset by half the width of said second digital diffractive optic regions; and an optical detection system positioned to receive and detect said manipulated beams of light from said digital diffractive optic track of said encoder member as spots of light that represent a digital absolute position value of said encoder member.