1. Arrangement for focus monitoring in a microscope with digital image generation, preferably in a confocal microscope, in which a parallel illumination beam path is provided in front of a main beam splitter arranged in the beam path, characterized in that a transparent optical component ( 4 ) with parallel beam entrance and beam exit surfaces is arranged in the area of this parallel illumination beam path ( 3 ) in front of the main beam splitter ( 6 ) in such a way that the mean perpendicular of the beam entrance surface lies parallel to the centroid of the illumination light ( 1 ), in that this transparent optical component ( 4 ) is supported so as to be rotatable and the mean perpendicular of the beam entrance surface encloses an angle &agr; with the centroid of the illumination light ( 1 ) during rotation, in that the axis of rotation ( 5 ) of this transparent optical component ( 4 ) is preferably situated in relation to the specimen ( 12 ) in such a way that a displacement of the beam bundle ( 9 a, 9 b ) is carried out in the main scanning direction or main image direction during rotation, and in that there is a central controlling and evaluating unit for controlling the transparent optical component ( 4 ), for processing the recorded images, for acquisition of all output data, and for calculating and evaluating the results.