Adaptable resolution optical encoder having structured illumination and spatial filtering
US9018578B2 · kind B2 · utility
Assignee
Inventors
Key dates
| Filing date | Dec 17, 2012 |
| Grant date | Apr 28, 2015 |
| Priority date | — |
| Expiry date | Jun 3, 2033 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG01D5/34794
- WIPO fieldMeasurement
- WIPO sectorInstruments
Abstract
A flexible optical displacement encoder configuration uses 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 provides spatial filtering to remove the high spatial frequencies from the modulation envelope to provide a clean signal in the detected fringe pattern. This combination of elements allows an incremental scale track pattern with a relatively finer pitch (e.g., 4, 5, 8 microns) to provide fringes with a coarser pitch (e.g., 20 microns) 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.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.