A laser printer is disclosed with three separate channels. Each channel includes a gas laser which projects a beam at a particular wavelength along the channel optical axis. A beam combiner receives the light beams from the three channels and combines them to form a combined beam spot at a registration plane. The combined beam spot is relayed to a polygon which scans the beam onto a receiving medium. In order to minimize laser pointing errors and eliminate artifacts in the image, optical means are provided for adjusting the size of the beam for optimum operation and for making the combined beam spot optically conjugate with a plane in each channel at a preselected point in the channel from which the pointing errors originate.