A giant mirror cell for a giant mirror (1996)

Each of the giant mirrors for the four Unit Telescopes of the VLT, with a diameter of 8.2-metres and a total area of more than 50 square metres, is supported by a complex steel structure, referred to as the M1 Cell. This structure also supports the M3 Tower that protrudes from the central hole of the mirror and carries a flat mirror (M3) that serves to reflect the light towards the Nasmyth platforms on either side of the telescope. On these platforms are placed the heavy instruments that will record the light from celestial objects collected by the telescope.

The M1 Cells were constructed by a consortium of GIAT Industries, Branche GITECH and SFIM Industries (France). Laser techniques were used for cutting and welding the single assemblies of the M1 Cell. This process is fully automatic and allows to generate very light and complex box-type structures starting from thin metal sheets. This also ensures an excellent stability with a comparatively low weight and is therefore ideal for the VLT M1 Cells.

An M1 Cell structure weighs approximately 10 tons, and has a very high stiffness-to-mass ratio.

The first M1 Cell (for UT1) arrived at Paranal in November 1997.