First light for the Active Phasing Experiment — a step towards the E-ELT

The 40-metre-class primary mirror of the European Extremely Large Telescope (E-ELT) will be composed of 984 individual segments, which must be aligned with incredible precision.

The position of the individual hexagonal mirrors needs to be controlled with nanometre precision (1 nanometre is 1 millionth of a mm). This can only be achieved with the help of new technologies and a prototype component for this high-tech alignment of segmented mirrors is seen in this image.

The so-called Active Phasing Experiment achieved its First Light during the night of 6 December 2008 on the visitor focus of Melipal, one of the 8.2 m Unit Telescopes of ESO’s Very Large Telescope at Paranal. Made in collaboration with several European partners, the current active segmented mirror is composed of 61 hexagonal segments.

You can move around the experiment in this Quicktime VTR animation.