The invention relates to an imaging system for optical automatic analysers, especially fluorescence readers. On the sample side, the imaging system contains a cylindrical lens array and a prism array, which is arranged upstream of the cylindrical lens array. The prismatic effect of the prisms of the prism array lies in the direction of the cylinder axes of the cylindrical lenses. Together with a telescopic imaging system, the inventive imaging system creates a number of parallel cylindrical focussing volumes between the cylindrical lens array and a detector array, these focussing volumes being slanted towards the optical axis of the telescopic system in relation to the vertical. The arrangement enables the detection of fluorescence with a large aperture in one direction, and at the same time enables depth selective analysis of the fluorescence signal, especially the discrimination of the fluorescent radiation originating from the solution above.