in a laser scanning microscope comprising a deflecting device , which is provided for variable deflection of a laser beam about a deflection angle , and a control unit , which controls the deflecting device via a control signal and measures , at least temporarily , a present deflection angle value , it is envisaged that , at the time of measurement of the present deflection angle value , a testing structure , which comprises at least one structural element whose position is assigned to a predetermined deflection angle value , is arranged downstream of the deflecting device , a detecting device is provided , which emits a detection signal when the laser beam is directed to the structural element , and the control unit assigns the present control signal to the predetermined deflection angle value upon reception of the detection signal .