New Adaptive Optics Module for Interferometry
NAOMI, or the New Adaptive Optics Module for Interferometry, is about to put the Very Large Telescope Interferometer (VLTI) on steroids. NAOMI modules will be installed on each of ESO’s 1.8-metre Auxiliary Telescopes (ATs), which form part of the VLTI at Paranal Observatory, bringing adaptive optics technology to the ATs.
Why? The ATs were equipped originally with a visible-light sensor called STRAP or System for Tip/tilt Removal with Avalanche Photodiodes. The STRAP system used a fast steering mirror to correct the slight, but rapid motion of the image of a star caused by the turbulence of the Earth's atmosphere. Under good seeing conditions, STRAP provided corrections that allowed astronomers to detect fainter objects in the Universe. But the system has limitations — as soon the conditions in the atmosphere degrade below a seeing of 1 arcsecond, the quality of the observations decays instantly. With NAOMI, the observations will be able to continue even when the conditions are less than superb, and they will be better under all conditions.
The goal of the project is to equip all four ATs with NAOMI modules, which contain a basic adaptive optics system, in place of the current STRAP sensor. As the ATs are small telescopes, they don’t require an advanced AO system such as SPHERE: NAOMI’s simpler implementation is sufficient to get the job done. With NAOMI, the ATs will be less sensitive to atmospheric conditions. The sensitivity of the VLTI’s current instruments like MIDI, AMBER and PIONIER will be improved and second generation instruments like GRAVITY will be able to reach their full potential.
NAOMI has two modes. The Full Adaptive Optics mode is the normal way in which NAOMI compensates for atmospheric turbulence, wind shake and telescope errors, while Tip-tilt mode is used for specific instruments like MIDI or MATISSE, and can be used on much fainter stars than the Full AO mode.
The first NAOMI module will arrive on Paranal in 2016, and the remaining three systems will be installed by the end of 2017.
The authoritative technical specifications as offered for astronomical observations are available from the Science Operation page.