Imaging system for luminescence assays

Apparatus for detecting luminescence in a sample, in which light emitted by the sample is collected for transmission photosensitive detector means by an optical fibre bundle the cross-sectional are of which corresponds to the are of the sample and one end of which is located close to but spaced from the sample for directly illuminating sample and collecting light emitted therefrom, selected ones of the fibres making up the bundle are separated from the remainder and extend to a light source to convey the light for direct illumination of the sample, and other fibres of the bundle serve to collect light emitted from the sample due to luminescence and provide a light path therefor to the photosensitive detector means, wherein the light collecting fibres are divided into a plurality of groups for conveying light to different regions of the detector means, thereby providing parallel light paths from the sample to the detector, and a wavelength selective filter is located in each of the said light paths to permit only selected wavelengths of light to reach the region of the detector means associated with each light path, and wherein the fibres in the bundle are arranged in a symmetrical pattern so that in the end face of the bundle presented to the sample, each sample illuminating fibre is surrounded by a ring of six light collecting fibres which, around the ring, successively constitute fibres appertaining to the respective groups of said light collecting fibres, whereby the sample illuminating fibres and the light collecting fibres are distributed uniformly over the area of the fibre bundle presented to the sample, and in which the apparatus is constructed to interrogate a well plate containing a plurality of wells, by investigating the luminescence characteristics of the plurality of wells at a time using a corresponding number of fibre bundles wherein two groups of collecting fibres from the plurality of fibre bundles are collected into two collection each of a corresponding number of fibre bundles, and each of the two collections is presented to one of two wavelength selective filters, each of which has a different wavelength filtering characteristic from the other, and two further bundles of optical fibres downstream of the filters separately collect and transfer light which is transmitted by the two filters, to two discrete regions of the detectors.