| 摘要 |
PROBLEM TO BE SOLVED: To provide an optical displacement encoder configuration that has an improved combination of high resolution, range/resolution ratio, compactness and robustness.SOLUTION: An optical displacement encoder configuration is configured to: use a source grating to illuminate a scale with structured light such that light from the scale is modulated with a beat frequency envelope, which may have a relatively coarse pitch that matches a desired detector pitch. An imaging configuration is configured to provide spatial filtering to remove high spatial frequencies from the modulation envelope to provide a clean signal in a fringe pattern to be detected. This combination of elements allows an incremental scale track pattern with a relatively finer pitch to provide fringes having a coarser pitch at a detector. Various scale resolutions can use a corresponding source grating, such that all combinations can produce detector fringes that match the same economical detector component. |
