AMOS was contracted by the European Southern Observatory (ESO) for the update of the ESO design, the realisation and the tests of the 12 Adapter-Rotators (8 Nasmyth and 4 Cassegrain Adapter-Rotators) for the four telescope units of the Very Large Telescope project.
The ESO Very Large Telescope consists of an array of four 8-meter Unit Telescopes, each equipped with two Nasmyth foci and one Cassegrain focus. Each focus is equipped with an Adapter-Rotator which provides the functions necessary for the fine position control of the telescope and for optimising the optical quality of the telescope. The Adapter-Rotators are the mechanical interface between the telescope and the scientific instruments. They are annular in shape to allow the light from the telescope beam to pass through the centre and reach the instruments.
The position control functions are contained within a mechanical assembly called Adapter and the instrument interface assembly is called the instrument Rotator.
Together they form an integral unit which is referred to as the Adapter-Rotator. The Nasmyth and the Cassegrain Adapter-Rotators have a similar function, but are not identical in size.