Interferometry method based on the wavelength drift of an illumination source
US7317541B2 · kind B2 · utility
Assignee
Inventor
Key dates
| Filing date | Jan 23, 2003 |
| Grant date | Jan 8, 2008 |
| Priority date | — |
| Expiry date | Apr 16, 2023 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG01B9/02079
- WIPO fieldMeasurement
- WIPO sectorInstruments
Abstract
An interferometry method using a laser of nominally fixed—but unknown and changing—frequency and phase angle, for example, attributable to laser drift. The interference pattern is periodically sampled at a frequency considerably higher than the phase shift of the object. The wavelength is reconstructed from the sampled patterns using a correlation algorithm. The phase angle is determined using an n-bucket algorithm. After all of the complex information has been determined at all of the multiple wavelengths, the surface of the object is calculated using conventional interferometry techniques. Accordingly, laser drift—typically considered a negative attribute—is used positively.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.