An exposure system for electrophotographic apparatus having an aperture plate for masking one or more laser beams. The plate (30) contains one or more apertures (52, 54, 56) which have irregular edges to form a gaussian light distribution for the light beams passing through the apertures. A saw-toothed edge is used with a predetermined amplitude ratio to predictably attenuate the light at the edges which correspond to the process or in-track direction in the exposed image. The gaussian distribution is more tolerable of spacing changes in scan lines and improves the continuity of process direction lines in the finished image.