Distance-independent optical reflectance instrument
US4568191A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Jul 1, 1983 |
| Grant date | Feb 4, 1986 |
| Priority date | — |
| Expiry date | Jul 1, 2003 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG01N2021/478
- WIPO fieldMeasurement
- WIPO sectorInstruments
Abstract
In known apparatus for taking reflectance readings the accuracy is very highly dependent on the distance between the transmitter and/or receiver area, on the one hand, from the surface whose reflectance is to be measured on the other. In the invention, in the field of measurement, the beam from a transmitter has superimposed on it the beam of at least one further transmitter so that within a wide range of operation readings are made independent of the distance between the said field on the one hand and the transmitter and/or receiver plane on the other and for this reason there is a deep range of measurement, that is to say compensation of depth. Preferably the transmitters are placed axially symmetrically with respect to the axis of the received beam (beam coming from the sample) or planarly symmetrical with respect to a plane containing the axis of the said beam.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.