A laser device for projecting a position mark in the field of vision onto an object to be examined using a mammography unit is described, where the laser device can be adjusted in position together with a vertically adjustable compression plate of the mammography unit. The stepping motor realizes smooth rotation and simplification in the structure of the rotor. The rastervector aligner generates an edge signal by edge filtering the raster data along a direction of the approximate vector and a smoothness signal by smoothness filtering the raster data along a direction of the approximate vector. The substantially constant radiation can be the output of a lamp powered by a constant current, direct current power supply. Both of these tasks can be facilitated by the use of a FIFO structure, through which the data flows.