Grazing incidence interferometry for measuring transparent plane-parallel plates
US5923425A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Nov 20, 1997 |
| Grant date | Jul 13, 1999 |
| Priority date | — |
| Expiry date | Nov 20, 2017 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG01B9/02058
- WIPO fieldMeasurement
- WIPO sectorInstruments
Abstract
A grazing incidence interferometer includes an extended light source for limiting spatial coherence of reference and test beams. A test plate is oriented at a grazing incidence to the test beam so that a first portion of the test beam is reflected from the front surface of the test plate, a second portion of the test beam is reflected from the back surface of the test plate, and the two test beam portions are sheared with respect to each other. The spatial coherence of the test beam is related to the lateral shear between the first and second test beam portions to significantly reduce contrast of an interference fringe pattern between the front and back surfaces of the test plate. Also, the reference beam is realigned with just one of the two test beam portions to favor the formation of an interference pattern between the reference surface and one of the front and back surfaces of the test plate over the formation of an interference pattern between the reference surface and the other of the front and back surfaces of the test plate.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.