High resolution digital diffraction grating scale encoder
US4629886A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Mar 20, 1984 |
| Grant date | Dec 16, 1986 |
| Priority date | — |
| Expiry date | Mar 20, 2004 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG01D5/38
- WIPO fieldMeasurement
- WIPO sectorInstruments
Abstract
An optical scale reader comprises a light source for radiating a beam of coherent light on a reflective scale, a half mirror for mixing light beams from the light source which are reflected and diffracted by the scale for interference with each other, an optical system for causing the interfering light beams leaving the half mirror on its opposite sides to be 90.degree. out of phase with each other so that the light beams will fall on the half mirror at a particular angle of incidence, photodetectors for detecting the interfering light beams, respectively, which have left the half mirror, and a signal processor for processing first and second electric signals which are supplied from the photodetectors and 90.degree. out of phase with each other to generate a signal indicative of the distance which the scale has moved. There is also disclosed a position control device incorporating the optical scale reader.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.