Patent ID: 7652266

Claim:
Apparatus for use in fluorescent resonant energy transfer assays for detecting the emission of fluorescent radiation from a sample in response to excitation by a radiation source, the sample containing at least two different probes, each probe comprising a donor/acceptor pair, the apparatus comprising: i) a sample irradiator for irradiating the sample with excitation radiation from at least two sources over the same time period, the two sources providing excitation radiation of different wavelengths; ii) a modulation arrangement for modulating the excitation radiation of each of said at least two sources according to a different respective modulation regime; and iii) an emission detector for detecting emission of fluorescent radiation from the sample, wherein the wavelength of the excitation radiation of each of said at least two sources is selected to excite a response from a different respective probe in the sample, and the emission detector is adapted to detect each of said different respective modulation regimes in emitted radiation such that responses of the at least two different probes to said at least two sources can be separately detected.