Interferometric optical phase discrimination apparatus
US4105335A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Jul 6, 1977 |
| Grant date | Aug 8, 1978 |
| Priority date | — |
| Expiry date | Jul 6, 1997 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG01B11/0675
- WIPO fieldMeasurement
- WIPO sectorInstruments
Abstract
Film of a known refractive index whose thickness is to be measured is illuminated by a white light beam. Two wave fronts from both sides of the film are directed to an interferometer. The wave fronts are out of phase in accordance with the thickness of the film. The two wave fronts are amplitude-split, respectively, by the beam splitter of the interferometer. Two of the split wave fronts are tilted by tilting means in the interferometer. The other two split wave fronts, as well as the two tilted wave fronts, are directed to an interference surface. Thus, there is formed a white interference pattern on the interference surface. The white interference pattern has a middle peak and two side peaks. The space interval between these peaks is measured by a scanner. By knowing the peak-to-peak interval, it is possible to discriminate the space interval between both sides of the film.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.