Optical layout (top panel) and the CAD model of one of the laser systems. Starting from the right the laser heads can be seen. In the beam path a pre-expander, polarization rotators, and a periscope assembly are installed before the constellation is generated and passed via fold mirrors towards the launch system. Diagnostics allow for an automatic pupil and field position control, stabilizing the constellation on sky. Average laser power and pulse shape measurements are built in. Finally, a safety shutter enables the beams to pass to the launch beam expander when opened.