Method and an apparatus for measuring a displacement between two objects and a method and an apparatus for measuring a gap distance between two objects
US5151754A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Oct 5, 1990 |
| Grant date | Sep 29, 1992 |
| Priority date | — |
| Expiry date | Oct 5, 2010 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG03F9/7023
- WIPO fieldOptics
- WIPO sectorInstruments
Abstract
A method and an apparatus for measuring a displacement between two objects. Corresponding pairs of regions of the two objects each have at least one diffraction grating which generate two-dimensionally distributed diffracted light beams. These light beams are diffracted and caused to interfere with each other in the paired regions, whereby two-dimensionally distributed diffracted interference light beams are emitted. A light beam of a specific order is detected from each of these diffracted interference light beams, and is converted into a beat signal. The displacement is obtained in accordance with the phase difference between these beat signals.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.