Optical movement measuring method and apparatus using interference fringes generated by overlapping spots of diffracted lights of different orders of diffraction from a line source
US5355220A · kind A · utility
Assignees
Inventors
Key dates
| Filing date | Aug 21, 1992 |
| Grant date | Oct 11, 1994 |
| Priority date | — |
| Expiry date | Aug 21, 2012 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG01P3/36
- WIPO fieldMeasurement
- WIPO sectorInstruments
Abstract
An optical movement measuring method and apparatus measures a movement of an object. A light from a light source is irradiated on a diffraction grating which is provided on the object so as to generate diffracted lights of different order of diffraction. The diffraction grating has light transmitting portions and light blocking portions which are alternately and periodically arranged. Interference fringes which comprises bright and dark stripes which occur alternately and are generated by overlapping spots of diffracted lights of different order of diffraction are detected, and a movement of the object is measured based on a counted number of stripes of the detected interference fringes.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.