19 December 2019

GRAUX participates in the realization of the project of all technological superlatives: the ELT!

The European giant telescope (ELT for Extremely Large Telescope) is the most ambitious project in the world and is supported by the European Southern Observatory (ESO). This telescope should allow major advances in the field of astronomy, in particular thanks to its primary mirror with a diameter of 39 meters.

When in June 2012 the ESO Board of Directors approved the construction budget for the giant telescope, the Dutch Minister in charge of Education, Culture and Science, Maria van der Hoeven declared “An almost unique level of international cooperation is achieved at ESO, and everything is done by those who can do it best, irrespective of their country or institution. This spirit of excellence is an example for all Europe. “.

GRAUX selected for its expertise in high vacuum technology.

GRAUX is part of this approach of excellence and has cutting-edge expertise in the manufacturing of industrial equipment using high vacuum technology. It is, among others, for these reasons that the manufacture of processing tools and stainless steel conveyors for transporting the mirror segments was entrusted to GRAUX.

The main mirror composed of 798 segments positioned with great precision.

The ELT telescope is composed of several mirrors of impressive formats which required extremely detailed studies and a level of production precision hitherto unattained.

Among these, the primary primary mirror M1 (f / 0.93) of the ELT has a diameter of 39 meters and, given its size, uses the segmented mirror technique, i.e. ‘it is made up of the assembly of several “small” mirrors. It includes 798 hexagonal elements 1.45 meters in diameter and 40 millimeters thick assembled like those of the Keck telescope in Hawaii. The mass of the primary mirror is 150 tonnes. The M1 mirror is supported by 30,000 supports which correct in real time the forces due to bending and deformation movements generated by the wind and the rotation of the mirror.

Schéma de l’ELT : M1 miroir primaire, M2 miroir secondaire, M3 miroir tertiaire, M4 miroir déformable (optique adaptative, M5 miroir renvoyant la lumière vers les plateformes instrumentales, 6 axe horizontal de la partie optique (hauteur), 7 plateforme instrumentale (x2), 8 lasers de l’optique adaptative (x6), 9 plateforme orientable (⇒azimut), 10 contreventements sismiques.

The regularly treatments of the mirror segments are carried out under high vacuum under extreme conditions.

These mirrors must receive a specific treatment renewed regularly. For this reason, and since the telescope is installed at an altitude of 3,000 meters in the Atacama Desert in northern Chile, ESO is building a mirror segment processing plant next to the giant telescope.

This specific treatment takes place under vacuum and requires specific tools to handle the mirrors in the vacuum chambers. And as happens in Chile, all the factory and all the tools must be able to manage the earthquakes without breaking glass …

Extreme conditions motivating the establishment of specifications demanding that GRAUX was able to win against a high level competition.