As a result of the size of the detector elements thereof, optoelectronic detectors such as photoelectron multipliers comprising a light-entry region sealed by a protective disc can only be used with much outlay for recording an image of a diffraction-limited focus volume in a two-dimensional spatially resolved manner, even if the image is significantly magnified in relation to the focus volume. The novel detector is intended to enable the spatially resolved detection of point spread functions with little outlay and high accuracy. 2.2 For this purpose, a body made of glass or glass ceramics comprising an opening, in which one end of an optical fiber is arranged, is cemented to the cover disc in such a way that the end of the optical fiber faces the cover disc and the optical axis thereof intersects the light-entry region. Thus, the relative position of optical fiber and entry region can be provided permanently with high accuracy. Preferably, the detector includes a plurality of detection channels, in particular 32 channels, comprising a respective light-entry region and the body includes a plurality of openings comprising a respective optical fiber. 2.3 Fluorescent microscopy.