Patent ID: 7595480

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 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; and 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; and an optical detection system positioned to receive said beam of light from said first and second digital diffractive optic regions of said encoder member to extract relative displacement information of said encoder member, wherein said first and second digital diffractive optic regions include curved grating microstructures configured to compensate for changes in angle between said beam of light and said first and second digital diffractive optic regions as said encoder member is rotated.