Optimised system for luminescence assays

An imaging system for measuring luminescence such as chemiluminescence produced by an array of samples such as a microtitre plate, wherein a presentation plate (12) is located immediately adjacent to or in contact with the sample plate (10) and presents the ends of a matching fixed array of optical fibres to at least part of the array of samples for conveying the luminescence emitted to a CCD camera. Typically the optical fibres are of plastic material having a numerical aperture (NA) greater than 0.2. For multi-labelled assay systems, the luminescence light can be analysed in two wavelengths simultaneously by means of a bifurcation of each of the fibres into two parallel filter channels. A second array of silica optical fibres can be incorporated for measuring epi-fluorcesence in addition. The fixed fibre array has the advantage over a lens based method of an absence of parallax and vignetting, no need to focus and more efficient light gathering.