Patent ID: 7449151

Claim:
A FRET (fluorescence resonance energy transfer) analyzer for measuring a FRET efficiency of a specimen containing a donor and an acceptor, the analyzer comprising: an illuminator for selectively emitting light for donor excitation and light for acceptor bleaching; a detector for detecting fluorescence emitted from the specimen in response to illuminating the specimen with the light for donor excitation, and generating an output corresponding to an intensity of the fluorescence; and a calculator for calculating the FRET efficiency using the output of the detector, the detector independently detecting light in first, second and third wavelength regions different from one another, the first wavelength region having a larger overlap with a fluorescence spectrum of the donor than with a fluorescence spectrum of the acceptor, the second wavelength region having a larger overlap with the fluorescence spectrum of the acceptor than with the fluorescence spectrum of the donor, and the third wavelength region having a larger overlap with the fluorescence spectrum of the acceptor than with the fluorescence spectrum of the donor, and having no substantial overlap with a wavelength region of the light for acceptor bleaching, the FRET analyzer further comprises a controller for controlling measurement of the FRET efficiency, the controller causing the illuminator to emit the light for donor excitation to cause fluorescence from the specimen, then causing the illuminator to emit the light for acceptor bleaching, determining whether the bleaching of the acceptor is completed according to an output in the third wavelength region of the detector, and when determining that the bleaching is completed, causing the illuminator to emit the light for donor excitation to cause fluorescence from the specimen.