Fiber optic continuous liquid level sensor
US4994682A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | May 19, 1989 |
| Grant date | Feb 19, 1991 |
| Priority date | — |
| Expiry date | May 19, 2009 |
Classification
- Technology area (CPC Y)Emerging Cross-Sectional Technologies
- CPC primaryY10S250/902
- WIPO fieldMeasurement
- WIPO sectorInstruments
Abstract
A fibre optic sensor, particularly for ascertaining fluid levels, utilizes two cylindrical lightguides with regular perturbations to emit and/or accept light in a radial direction. Each waveguide is coupled to one (or more) light source and/or to one (or more) light detector. A light source such as a light emitting diode or laser diode is coupled to the lightguide which emits radially, illuminating a planar dielectric surface, which in the presence of a fluid with a low index of refraction, e.g. air, behaves as a mirror, coupling light via total internal reflection to the lightguide which accepts this light radially and channels the light to a light detector. In the presence of a fluid with a high index of refraction, for example water, at the planar dielectric surface the fluid dielectric interface becomes primarily transmissive, with relatively little light being coupled to the lightguide which accepts light radially. The optical signal received at the light detector is thus related to the depth of the planar dielectric surface which is immersed in liquid. Several different embodiments to achieve liquid level sensing, as well as a scheme for eliminating sensitivity to optical sig…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.