Optical scanning microscope with line scanning and with illumination of a specimen via a beam splitter, which is arranged in an objective pupil and includes at least a reflecting first portion and at least a transmitting second portion, whereby the reflecting portion serves to couple in the illumination light and the transmitting portion serves to pass the detection light in the detection direction or the transmitting portion serves to couple in the illumination light and the reflecting portion serves to couple out the detection light, with a first scanning arrangement, whereby a mechanism is provided in the detection light path for the overlay of at least one further scanning arrangement for illumination and detection.