Method and apparatus for detecting and sizing particles on surfaces
US4967095A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Sep 25, 1989 |
| Grant date | Oct 30, 1990 |
| Priority date | — |
| Expiry date | Sep 25, 2009 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG01N2015/0681
- WIPO fieldMeasurement
- WIPO sectorInstruments
Abstract
A method and apparatus for detecting and classifying particles on a surface in which condensation is used to enlarge particles. An apparatus of the present invention includes a heatable wick disposed over a test surface and in fluid communication with a source of volatile liquid. A zone of vapor supersaturation is thus created in which condensation on particles on the surface can occur. A light beam directed onto the surface scans the surface. Droplets are detected by means of light scattered from the droplets. In an alternate embodiment a stream of carrier gas may be provided around the wick or bubbled through a jar of volatile liquid to direct a vapor toward the test surface. In another embodiment, multiple wicks communicate with different sources of volatile liquids. In a method of the invention, mulitple scans are made with either different levels of vapor supersaturation or different vapor compositions. Comparing particles in each scan allows one to classify particles into different size ranges or chemical type.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.