Laser — do not look into the beam!

The drone-mounted camera that took this aerial video sequence has done something that no human being could safely do — it has stared directly into the beams of the four lasers attached to Yepun, one of the four Unit Telescopes that make up ESO's Very Large Telescope. The result is this spectacular aerial video in which we see the powerful yellow laser beams that are projected into the sky from the telescope structure. The purpose of each laser is to create an artificial guide star high in the atmosphere. At a height of about 90 kilometres, the laser encounters a layer of sodium atoms, which are excited by the laser's energy to produce a small glowing patch. This appears much like a star in the sky and by following its jittery movement the adaptive optics system can compensate for the blurring effect of the turbulent atmosphere and ensure very sharp images.