Extended range interferometric refractometer
US6128080A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Jun 6, 1997 |
| Grant date | Oct 3, 2000 |
| Priority date | — |
| Expiry date | Jun 6, 2017 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG01N21/45
- WIPO fieldMeasurement
- WIPO sectorInstruments
Abstract
A method and apparatus is disclosed for measuring the refractive index difference between a reference and sample liquid based on an interferometric design. The resultant device has an almost unlimited range of operation in contrast to a conventional interferometric refractometer of the so-called polarization type whose dynamic range is restricted to a relatively narrow range of refractive indices. The measurement of the refractive index difference between a sample and reference cell is achieved by measuring the angle through which the plane of polarization of a combined beam has rotated. For the conventional device, this angle is restricted to about .pi. radians which corresponds to a half wavelength shift between the reference and sample components of said combined beam. The extended range device disclosed permits this angle to be tracked and measured accurately over many rotations. The rotation tracking is achieved by one of three embodiments, the preferred of which involves the use of a liquid crystal retarder. The other two techniques incorporate, respectively, a rotating polarizer and a doubly split beam. All three embodiments permit the measurement of both the sine and cosine…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.