To obtain a method and a device for homogenizing laser beams in a use wherein a plurality of pulses are used for piercing in a projection imaging arrangement.

In the device for homogenizing pulse laser beams for being used in a plurality of pulse piercing arrangements wherein the image of a mask is projected on the surface of a workpiece, a mirror which is composed so as to reflect the pulse laser beams to the mask and a scanning device which moves the mirror so that the central axis of the pulse laser beams traces a pattern on the mask and which is composed so that the image of the mask projected on the surface of the workpiece over a long period shows nearly equal intensity in the whole areas where the laser light beams are projected are provided.