The Rise of a Giant (II): Daily Outside View

Birds eye view of the elaborate 3-dimensional model of the Extremely Large Telescope developed to determine expected performance during observing conditions. With a 40-metre-class diameter primary mirror, the present baseline, its total rotating mass is 5500 tons. The two platforms on each side of the structure hold large instruments. The telescope features a novel, innovative design, based on 5 mirrors. The primary 40-metre-class mirror is composed of almost 800 segments, each 1.45 m wide, while the secondary mirror is as large as 4.2 metres in diameter. A tertiary mirror, 3.75 m in diameter relays the light to the adaptive optics system, composed of two mirrors: a 2.5-m mirror supported by 5000 or more actuators so as to be able to distort its own shape a thousand times per second, and one 2.7 m in diameter that allows for the final image corrections. This five mirror approach results in an exceptional image quality, with no significant aberrations in the field of view.

The design for the ELT shown here was published in 2009 and is preliminary.