Patent ID: 7502127

Claim:
A sensor device comprising: a reference grating having a configuration that is varied periodically in two dimensions; a light source emitting light to the reference grating; a spectral unit disposed between the light source and the reference grating and having a plurality of openings configured to convert the light emitted by the light source into a plurality of parallel light beams through the plurality of openings, wherein said plurality of parallel light beams output from the spectral unit reach the reference grating directly without changing respective spaces between the light beams and each of said plurality of parallel light beams is reflected by the reference grating; and a detector unit comprising a photodetector configured to receive the light beams reflected by the reference grating, wherein the detector unit is configured to detect a state of a movable body relative to the reference grating based on a change of the reflected light beams collectively received by the photodetector.