Method and apparatus for profiling surfaces using diffracative optics
US5671050A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Dec 28, 1994 |
| Grant date | Sep 23, 1997 |
| Priority date | — |
| Expiry date | Dec 28, 2014 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG01B11/303
- WIPO fieldMeasurement
- WIPO sectorInstruments
Abstract
Optical system for measuring surface topography, comprised of a light source (30), a diffractive optical assembly (70,72,73) comprised of two or more diffraction gratings, holograms or like diffractive optics (120, 130;122, 132;123, 133), electronic detection means and digital signal processing means (10, 110) for determining surface height from interference data. The diffractive optical assembly (70,72,73) divides the incident light into two beams (150,160;152,162;153,163), which subsequently impinge upon the object (20) at the same place on the object surface (70) but at two different angles of incidence. After reflection from the object surface, the beams pass separately back through the diffractive optical assembly (70,72,73), after which they combine once again and form an interference pattern representative of the surface topography. The equivalent wavelength of the resultant interference pattern is much greater than the illumination wavelength.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.