Displacement measurement device, exposure apparatus, and working device
US8749761B2 · kind B2 · utility
1Cited by
6References
17Claims
0Family size
Assignee
Inventors
Key dates
| Filing date | Dec 2, 2010 |
| Grant date | Jun 10, 2014 |
| Priority date | — |
| Expiry date | Aug 20, 2032 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG01B2290/70
- WIPO fieldMeasurement
- WIPO sectorInstruments
Abstract
A device has a scale on which a grating pattern is formed, a light source to irradiate light on the scale, a wavelength plate to transform multiple diffracted lights from the light source into circular polarized light, respectively, an optical element to superposition and cause interference of the multiple diffracted lights, and a photodetector to receive the interfered light. Also, a generating unit to generate linearly polarized light by the light from the light source, so that the multiple diffracted lights input to the wavelength plate become linearly polarized light with a same mutual polarization direction.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.