Beam masking to reduce cyclic error in beam launcher of interferometer
US6922249B1 · kind B1 · utility
Assignee
Inventors
Key dates
| Filing date | Nov 12, 2002 |
| Grant date | Jul 26, 2005 |
| Priority date | — |
| Expiry date | Sep 11, 2023 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG01B2290/15
- WIPO fieldMeasurement
- WIPO sectorInstruments
Abstract
Embodiments of the present invention are directed to reducing cyclic error in the beam launcher of an interferometer. In one embodiment, an interferometry apparatus comprises a reference beam directed along a reference path, and a measurement beam spatially separated from the reference beam and being directed along a measurement path contacting a measurement object. The reference beam and the measurement beam have a single frequency. At least a portion of the reference beam and at least a portion of the measurement beam overlapping along a common path. One or more masks are disposed in the common path or in the reference path and the measurement path to spatially isolate the reference beam and the measurement beam from one another.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.