Grating measurement apparatus
US10571245B2 · kind B2 · utility
Assignee
Inventors
Key dates
| Filing date | Jul 27, 2017 |
| Grant date | Feb 25, 2020 |
| Priority date | — |
| Expiry date | Jul 27, 2037 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG01B2290/70
- WIPO fieldMeasurement
- WIPO sectorInstruments
Abstract
A grating measuring device includes: a light source module (300) for generating two light beams having different frequencies, one of which serves as a measuring beam and the other as a reference beam; a grating (200); and a grating measuring probe (100) including a dual-frequency light reception module, a vertical measurement module, a vertical detection module and a reference detection module. The dual-frequency light reception module is configured to receive the measuring and reference beams, and the vertical measurement module is adapted to project the measuring beam onto the grating (200), collect a zeroth-order diffracted beam resulting from double diffraction occurring at the grating, and feed the zeroth-order diffracted beam to the vertical detection module. The zeroth-order diffracted beam interferes with the reference beam in the vertical detection module, resulting in a vertical interference signal. In addition, the measuring and reference beams interfere with each other also in the reference detection module to result in a reference interference signal. The vertical and reference interference signals are received by a signal processing module and serve as a basis for cal…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.