Method and apparatus for optically measuring characteristics of a thin film by directing a P-polarized beam through an integrating sphere at the brewster's angle of the film
US4873430A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Oct 25, 1988 |
| Grant date | Oct 10, 1989 |
| Priority date | — |
| Expiry date | Oct 25, 2008 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG01N2201/065
- WIPO fieldMeasurement
- WIPO sectorInstruments
Abstract
A method for optically measuring at least one characteristic of a thin film on a reflecting substrate. A p-polarized beam of collimated light of known intensity is directed through an integrating sphere onto the film at substantially the Brewster's angle of the film. All the light is reflected into the sphere, including all diffusely reflected light as well as the light specularly reflected at a region inside the sphere where the specularly reflected light is incident. A reflective surface is provided for determining the thickness of the film as a function of the total intensity of light sensed within the sphere. An absorptive surface is provided at said region for absorbing the specularly reflected light for determining the porosity or surface roughness of the film based on the intensity of the diffused light sensed within the sphere not reflected from the substrate.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.