Apparatus and method using optical diffraction to measure surface roughness
US5488476A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Oct 12, 1994 |
| Grant date | Jan 30, 1996 |
| Priority date | — |
| Expiry date | Oct 12, 2014 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG01B11/303
- WIPO fieldMeasurement
- WIPO sectorInstruments
Abstract
Apparatus for measuring surface roughness utilizes diffraction patterns derived from the surface under test. The energies in the different orders are detected and processed utilizing various different algorithms dependent upon a number of factors such as the number of orders in the diffraction pattern and asymmetry in the diffraction pattern. Various filter functions both for the diffraction pattern itself and for values of surface roughness after measurement are disclosed. One algorithm for measuring surface roughness involves comparison of values representing the energy orders with reference values, preferably reference values obtained by an interpolation operation between one set of reference values representative of a diffraction pattern from a symmetrical surface and another set representative of a diffraction pattern from an asymmetrical surface.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.