Particle detector for flowing liquids with the ability to distinguish bubbles via photodiodes disposed 180.degree. apart
US4783599A · kind A · utility
26Cited by
8References
11Claims
0Family size
Assignee
Inventor
Key dates
| Filing date | Feb 10, 1987 |
| Grant date | Nov 8, 1988 |
| Priority date | — |
| Expiry date | Feb 10, 2007 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG01N2021/4707
- WIPO fieldMeasurement
- WIPO sectorInstruments
Abstract
A system for detecting contaminant particles in a liquid, such as used for processing wafers during the manufacture of integrated circuits, distinguishes non-contaminant bubbles generally found in liquids from contaminant particles. The system provides a controlled laminar fluid flow of the liquid through a pipe, and the substantially spherical bubbles in the flow path are detected by symmetrically spaced photodiodes. The irregularly shaped contaminant particles are detected, whereas the presence of bubbles are negated by the detection system by virtue of the balanced photodiode assembly.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.