Optical apparatus for measuring transmission or absorption along a measurement path
US4432649A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Jun 4, 1981 |
| Grant date | Feb 21, 1984 |
| Priority date | — |
| Expiry date | Jun 4, 2001 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG01N2201/066
- WIPO fieldMeasurement
- WIPO sectorInstruments
Abstract
A light transmitter transmits a beam of light along a measurement path to a light receiver which receives the light beam either directly or via a retro-reflector. The light receiver forms electrical signals representative of the transmission or absorption along the measurement path. In an arrangement with separate light transmitter and receiver units these units are arranged in respective housings at each end of the measurement path. In an alternative arrangement in which the light transmitter and receiver are in a single unit a retro-reflector is positioned at the other end of the measurement path. In this alternative arrangement the light transmitter/receiver unit is embodied in one housing and the retro-reflector in a second housing. In either arrangement both housings are sealingly closed by at least one and preferably two windows which can be moved cyclically into and out of the light beam. The transmission or absorption along the measurement path is calculated from the signals in such a way that the measured absorption is independent of the prevailing level of contamination. The apparatus is particularly useful for transmission measurements in chimneys and on airfields.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.