An arrangement for the detection of the illumination radiation in a laser scanning microscope, wherein a portion of the illumination radiation is coupled out and detected at the main color splitter, wherein light transmitted through the main color splitter is advantageously detected and/or a portion of the illumination radiation is coupled out and detected before coupling into a light-conducting fiber and/or a portion of the illumination radiation is coupled out and detected at a beam splitter arranged downstream of a light-conducting fiber.