ملف:Unit Telescope 4 at VLT operates the 4LGSF (UT4 LGS-CC).tif

English: Unit Telescope 4 (Yepun) of ESO's Very Large Telescope (VLT) sends laser light up into the sky over the Chilean Atacama Desert. The laser light creates an artificial guide star, which functions as part of the Adaptive Optics (AO) system, state-of-the-art technology that corrects the blurring effects of Earth's atmosphere to produce sharper images of astronomical objects. The AO system is just one aspect of the sophisticated technology installed on the VLT that makes it the world's most advanced optical instrument. This status means it is well placed to make the most of the exceptionally clear skies that it has a front-row view of.