Optical configuration for imaging-type optical encoders
US7186969B2 · kind B2 · utility
Assignee
Inventors
Key dates
| Filing date | Mar 19, 2004 |
| Grant date | Mar 6, 2007 |
| Priority date | — |
| Expiry date | Oct 7, 2024 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG01D5/36
- WIPO fieldMeasurement
- WIPO sectorInstruments
Abstract
A displacement measuring device including a scale, and an optical readhead including an index pattern and a light receiving element is provided. A bright/dark pattern arising from a scale grating is detected by the readhead to measure displacement. In various embodiments, a magnification of the pattern is adjusted by the spacing between at least a lens element, aperture element, and detection plane of the readhead. An aperture can be designed to provide a diffraction-limited telecentric imaging configuration that filters an image of the scale grating to provide a sinusoidal intensity pattern that supports highly interpolated measurements. An aperture dimension, selected in relation to the grating pitch and other parameters, can provide a desirable combination of readhead operating characteristics including one or more of a desired depth of field; degree of spatial filtering; and optical signal power.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.