Method and apparatus to detect the presence of water on a surface
US6680479B1 · kind B1 · utility
Assignee
Inventor
Key dates
| Filing date | Sep 25, 2000 |
| Grant date | Jan 20, 2004 |
| Priority date | — |
| Expiry date | Sep 25, 2020 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG01J3/427
- WIPO fieldMeasurement
- WIPO sectorInstruments
Abstract
A water detecting apparatus includes a source of infra-red radiation which is reflected off an inner surface of a pipe wall onto a mirror directing the infra-red signal along a path to an infra-red detector connected by an electrical signal path to an electronic control. The path is interrupted by a rotating chopper having windows occupied by two optical filters. The first optical filter only passes an infra-red signal of wavelength 1900 nm which is absorbed by water, while the second optical filter only passes an infra-red signal of wavelength 2200 nm, another wavelength absorbed by water, but not to the same extent as the 1900 nm wavelength. The 2200 nm wavelength serves as a reference signal. When the strength of the infra-red signal path by the first optical filter decreases in relation to the strength of the infra-red reference signal path by the second optical filter, this is due to water on the surface absorbing the 1900 nm wavelength more than the 2200 nm wavelength, and the electronic control causes an indicator to indicate the presence of the water.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.