Apparatus and method for phase resolved fluorescence lifetimes of independent and varying amplitude pulses
US5317162A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Sep 9, 1992 |
| Grant date | May 31, 1994 |
| Priority date | — |
| Expiry date | Sep 9, 2012 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG01N2015/1477
- WIPO fieldMeasurement
- WIPO sectorInstruments
Abstract
A flow cytometer measures phase fluorescence lifetimes by the phase shift of a reference signal and an emission from a particle or cell in a flow chamber. An acoustic optic modulator modulates laser light with a sinusoidal wave of a predetermined frequency to excite particles or cells. Detectors respond to emissions of individual particles or cells in the form of an output signal pulse at the predetermined frequency. The output signal pulse is divided into equal pulses with each at the modulation frequency, the same amplitude and fidelity and amplitude. One part of the divided pulse is stripped of its envelope to pass the width thereof and out of band components are rejected. A variable amplifier passes a portion of the pulse above a present level. A delay line sets a central part of the signal at a predetermined point in time. A circuit limits the attenuated one part. A double balance mixer multiplies and the relates the limited signal with a reference signal to determine the phase shift. A method measures phase fluorescence lifetimes of cells or particles with fluorescent markers by passing individual cells or particles in a flow stream of a flow chamber in a flow cytometer.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.