Photon counting fluorimeter
US4320970A · kind A · utility
Inventors
Key dates
| Filing date | Jun 22, 1977 |
| Grant date | Mar 23, 1982 |
| Priority date | — |
| Expiry date | Jun 22, 1997 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG01N21/276
- WIPO fieldMeasurement
- WIPO sectorInstruments
Abstract
An ultraviolet light beam is split into two beams which are directed toward a reference cell and a sample cell, respectively. A mechanical rotating light chopper permits the reference and sample cells to be alternately illuminated. Radiation from the reference and sample cells is directed toward and sensed by a single photomultiplier tube. An up/down counter counts the number of photons impinging on the photomultiplier tube from the reference and sample cells. Photodiodes in conjunction with the mechanical light chopper cause the up/down counter to count up when photons are arriving from the sample cell and cause the up/down counter to count down when photons are arriving from the reference cell. A source intensity monitor prohibits further measurements after a preselected amount of incident flux has been sensed. The intensity monitor includes a photodetector circuit which senses a portion of the incident light. Pulses from the detector are fed to a counter and the number in the counter is compared to a preselected number which is set on a thumbwheel switch. When the comparison condition is met, the up/down counter of the fluorimeter is stopped.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.