Optical system for the removal of inhomogeneities in the intensity distribution of the laser radiation

An optical system (10) for the removal of inhomogeneities in the intensity distribution of laser radiation, particularly for a plant for processing thin film layers includes a beam shaping device (12) which is adapted to form a laser beam (14) such that a beam profile ( 36) of the laser beam (14) has a long axis (having y) and a short axis (x). The optical system (10) further comprises in the beam path of the laser beam (14) of the beam shaping means (12) downstream of the imaging device (18) which is arranged for imaging the thus shaped laser beam (14) as a line of illumination (22). Further, the optical system (10) comprising a diaphragm device (30) with at least one spatially variable aperture element (32, 32a, 32b), which is adapted, in the beam path of the laser beam (14) in at least one side (34, 34a, 34b) of the beam profile (36) extending along the long axis (y) of the beam profile (36) to protrude such that by partially hide the beam profile (36), the beam profile (36) a localized recess (38, 38a, 38b) at the at least one side (34, 34a, 34b) of the beam profile (36), wherein through the spatial variation of the screen member (32, 32a, 32b) a size of the localized recess (38, 38a, 38b) can be changed. The optical system (10) further comprises a control unit (52) which is adapted to the spatial variation of the screen member (32, 32a, 32b) to control so that the size of the localized indentation increased several times over a predetermined period of time and reduced becomes.