Analysis apparatus
US4463261A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Apr 5, 1982 |
| Grant date | Jul 31, 1984 |
| Priority date | — |
| Expiry date | Apr 5, 2002 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG01N21/55
- WIPO fieldMeasurement
- WIPO sectorInstruments
Abstract
For indication of the amount of a constituent in a substance, for example the proportion of moisture in hay, a pair of light-emitting diodes 1 and 2 have their emissions reflected from the substance being analyzed. The diodes emit radiation in narrow bands selected so that there is differential reflection depending on the proportion of the constituent in the substance. The supply currents to the diodes are switched in alternate sequence and their relative magnitudes adjusted to give minimum output at the switching frequency. For determining the proportion of moisture in hay suitable wavelengths are 1450 nm and 1300 nm. The diodes may be constructed as InGaAsP/InP diodes with the proportions of the constituents adjusted to give emission at the required wavelengths.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.