Apparatus and method for fluorescent lifetime measurement
AssigneeBecton, Dickinson and Company
InventorsBertram G. Pinsky, John J. Ladasky, Jr.
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Abstract
A flow cytometer measures fluorescence lifetimes by the phase shift of a reference signal and an emission from a fluorescent particle or cell in a flow chamber in order to identify the particle or cell. 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. Signals representative of fluorescence emitted and reference beam signals is measured. The particle is identified by the phase shift.
Claims15
A method of identifying a particle for use in a flow cytometer, the method comprising the steps of:
- providing a beam of light;
- intensity modulating the beam of light;
- passing the particle through the beam of intensity modulated light;
- collecting light from the particle for use as a reference;
- collecting fluorescence emitted by the particle;
- generating a first signal in response to the light collected as a reference and a second signal in response to the fluorescence collected;
- and
- determining the difference in phase between the first signal and the second signal.
A flow cytometer comprising:
- means for producing a light beam;
- means for intensity modulating the light beam;
- means for passing a fluorescently tagged particle through the modulated light beam such that light is the particle emits fluorescence on passing through the light beam;
- first fluorescence detecting means for detecting the fluorescence and generating a fluorescence signal in response to the fluorescence;
- means for determining the phase shift between the fluorescence light and the modulated light beam.
Dependencies are inferred from the claim text.