Method and apparatus for detection, analysis and identification of particles
US5515163A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Sep 1, 1994 |
| Grant date | May 7, 1996 |
| Priority date | — |
| Expiry date | Sep 1, 2014 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG01N2021/4792
- WIPO fieldMeasurement
- WIPO sectorInstruments
Abstract
A method and an apparatus for the analysis of particles contained in a material, such as particles in a fluid or on a surface, such as the surface of a semiconductor, by two orthogonally polarized, intensity and phase modulated laser beams, wherein the detected scattered light is synchronously demodulated. The apparatus comprises a laser source producing a polarized laser beam, a state of polarization modulator, and a photoreceiver for detecting light scattered by particles at an angle to the incident light. A synchronous demodulator, such as a dual channel lock-in amplifier, separates the intensity and phase modulated portions of the scattered signals. A reference unit for detecting a non-scattered light produced by the sample to provide a reference is preferably provided, as well. The size, index of refraction and identity, of the particles, for example, can be determined.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.