|Description:|| NOVA-ASTRON is currently building the Cold Optical Bench (COB) for MATISSE, the mid-infrared interferometric spectrograph and imager for ESO's VLT interferometer (VLTI) at Paranal, Chile. Matisse can combine the light from all 4 eight-meter VLT telescopes.|
By coherently adding the light from these telescopes, MATISSE is capable of imaging at spatial resolutions of ~6 milli-arcsec in the 2.8-5 and 8-13 micrometer wavelength range. This enables the study of wavelength-dependent characteristics of gas and dust grains. This includes the formation and evolution of planetary systems, Active Galactic Nuclei and high-contrast environment of evolved stars.
The COB is the most complex part of MATISSE. It accommodates ~200 optical components, located into two boxes of roughly 70x70x40cm size, with over 8x20m(!) optical path length. The COB units will be mounted in 2 cryostats, which have been built by the Max Planck Institute for Astronomy in Heidelberg, Germany.
The COB is accommodated in 2 backbone structures, each milled from a single block of aluminum in order to meet the stringent stability and accuracy requirements, going down to tolerances of 0.02mm. Being originally 600kg in weight, the blocks were whittled down to ~70kg in their final shape. Together with the dummy backbone, which was realized last year, these are the largest parts ever milled on NOVA's large Hermle C40 milling machine. In fact they were even a bit too large for the machine, necessitating some imaginative strategies.
This masterpiece of precision milling has only been possible thanks to an intense collaboration between NOVA-ASTRON's designers, manufacturing engineer and machine operator, combined with a detailed knowledge of the machine properties.