Embedded interferometer for reference-mirror calibration of interferometric microscope
US6545761B1 · kind B1 · utility
Assignee
Inventors
Key dates
| Filing date | Nov 30, 1999 |
| Grant date | Apr 8, 2003 |
| Priority date | — |
| Expiry date | Nov 30, 2019 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG01B2290/60
- WIPO fieldMeasurement
- WIPO sectorInstruments
Abstract
A laser interferometer is embedded into an interference microscope to precisely determine the in-focus position of the microscope objective's reference mirror. A collimated laser beam is introduced into the microscope system and split into two beams directed toward a calibration reference surface and the interference objective. The light reflected from the calibration reference surface is returned to the camera. The light into the interference objective is focused onto the reference mirror and returned to the camera. For the purpose of calibration, the two beams are combined at the camera to produce interference fringes. When the reference mirror is in focus, the returned beam is collimated; if the mirror is on either side of focus, the beam is either converging or diverging. Accordingly, the interferogram produced at the camera reflects the in-focus or out-of-focus condition of the reference mirror. The curvature of the wavefront returned from the reference mirror is determined electronically by analyzing the interference fringes produced with the beam returned from the calibration reference surface. By minimizing the curvature of the reference-mirror wavefront as the mirror is tr…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.