The present invention relates to a system and a method for microlithographic writing on photosensitive substrates, and specially printing of patterns with extremely high precision, such as photomasks for semiconductor device patterns, display panels, integrated optical devices and electronic interconnect structures. The system comprises a light source (1), preferably a laser, a computer-controlled light modulator (3) and a lens to contract the at least one light beam from the light source before it reaches the substrate. Further it comprises a device for controlling the position of incidence of the beam on the substrate, a detector for detecting the deviation from the intended position of incidence of the beam on the substrate, and correcting device for controlling the position controlling to device in accordance with the detected deviation diminish position errors at the substrate related to the deviations.