Photoluminescent indicator
US4374328A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Apr 27, 1981 |
| Grant date | Feb 15, 1983 |
| Priority date | — |
| Expiry date | Apr 27, 2001 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG01L11/02
- WIPO fieldMeasurement
- WIPO sectorInstruments
Abstract
A photoluminescent indicator apparatus having automatic feedback means to maintain the sensitivity of the indicator apparatus with respect to variations in environmental conditions. The apparatus includes a sample of photoluminescent material having a photoluminescent decay rate which varies as a function of environmental conditions. The sample is positioned in a remote location having some unknown aspect of the environment desired to be measured. The sample is optically excited with a modulating signal to generate an excitation output signal functionally dependent on the modulating signal and indicative of the unknown environmental condition. A phase detection means is provided for comparing difference in phase between a phase reference signal and the excitation output signal to generate a phase differential signal functionally related to the photoluminescent decay rate of the sample. The indicator apparatus includes an automatic feedback means for adjusting the phase reference signal in accordance with the phase differential signal.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.