Interferometric measuring apparatus for making absolute measurements of distance or refractive index
US5541730A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Sep 30, 1994 |
| Grant date | Jul 30, 1996 |
| Priority date | — |
| Expiry date | Sep 30, 2014 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG01B2290/60
- WIPO fieldMeasurement
- WIPO sectorInstruments
Abstract
An absolute interferometer has part of the beam paths making up its measuring and reference arms formed in a waveguide, and part formed in air. The part formed in the waveguide are common mode so that the path length difference is formed in air, thus minimizing inaccuracies in the measurements caused by temperature changes in the waveguide. Phase modulators in the waveguide enable interpolation of the fringe counts to be made to high resolution. The absolute interferometer may be combined with a tracking interferometer, and with air refractometers, all of which have parts of their measuring and reference arms in the waveguide in common mode and symmetrical with each other.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.