Position measuring apparatus
US6080990A · kind A · utility
Assignees
Inventors
Key dates
| Filing date | Mar 18, 1998 |
| Grant date | Jun 27, 2000 |
| Priority date | — |
| Expiry date | Mar 18, 2018 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG03F9/7088
- WIPO fieldOptics
- WIPO sectorInstruments
Abstract
A position measuring apparatus includes a light source 1, an illumination optical system 100, a light-reception optical system 400 and a light-receiving unit 500. Illuminating beam emitted from the light source 1 is diffracted by a two-dimensional pattern on an object 10, and then enters the light-reception optical system 400. The light-receiving unit 500 receives diffracted lights consisting of a combination of a higher-order diffracted light appearing on the object side for the zero-order diffracted light in the receive diffracted lights with a zero-order diffracted light different in frequency from the higher-order diffracted light and another combination of higher-order diffracted lights different in frequency from one another and appearing on the object side for the zero-order diffracted light, thereby forming a position measuring interference measurement signal within the plane including the object. A signal processing unit is adapted to measure the position of the object 10 based on the phase of the position measuring interference measurement signal.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.