ESPRESSO instrument achieves first light with all four Unit Telescopes

The ESPRESSO instrument on ESO’s Very Large Telescope in Chile has used the combined light of all four of the 8.2-metre Unit Telescopes for the first time. Combining light from the Unit Telescopes in this way makes the VLT the largest optical telescope in existence in terms of collecting area. This picture shows in highly simplified form how the light collected by all four VLT Unit Telescopes is combined in the ESPRESSO instrument, located under the VLT platform.