The ESO’s Very Large Telescope (VLT) fourth telescope (Yepun) has just been changed into a fully adaptive telescope. After more than a decade of planning construction and testing, the new Adaptive Optics (AOF) device captured its first light through the MUSE instrument, delivering incredibly resolute images of planetary nebulae and galaxies. The coupling of AOF and MUSE forms one of the most advanced and powerful systems, technologically speaking, ever built for the needs of ground astronomy.

A peak adaptive optics device captures its first light

The installation of adaptive optics (AOF) is a project long-term intended to develop a system of optical adaptive instruments of the fourth telescope (UT4) Very Large Telescope (VLT) at ESO. The first of them to benefit from it is MUSING, the multi-unit spectroscopic explorer (1). Adaptive optics aims to compensate for the interference of images generated by the atmosphere of the Earth thus to enable MUSE to acquire images. That is much sharper and more contrasting than before. Now, MUSE can study the weakest objects in the Universe.

The AOF, which allowed these observations, is composed of many elements working together. Among these are the four-star set of laser guides (4LGSF) and the very thin deformable secondary mirror of the UT4 (3) (4). All 4LGSF emits four laser beams 22 watts for exciting the atoms of sodium present in the upper atmosphere, and therefore generate artificial stars in the sky.

The sensors of the module, GALACSI (Adaptive Lower Atmospheric Corrector for Spectroscopic Imaging) adaptive optics use these artificial star guides to determine atmospheric conditions at the time of observation. Every 1000th of a second, the AOF system calculates the distortion to be applied to the deformable secondary mirror of the telescope to compensate for local atmospheric disturbances.

GALACSI corrects including the effects of the turbulence prevailing in the atmospheric layer thousand meters thick overlooking the telescope. Depending on the conditions, atmospheric turbulence may vary with altitude. However, Studies have shown that the majority of atmospheric disturbances occur in this low layer of the atmosphere. Adopting the AOF system means raising the VLT by some 900 meters and therefore keeping it above, the most turbulent atmospheric layer says Robin Arsenault, head of the AOF project.

In the past, acquiring images with greater clarity involved finding a more appropriate site or using a space telescope and today. Thanks to the AOF, Observation at the very location where we are, at a much more affordable cost. The corrections made by the AOF quickly and continuously improve image quality by concentrating light to form finer images, enabling MUSE to acquire details that are more resolute and detect weaker stars than before.

http://www.thetechnologylounge.com/wp-content/uploads/2017/08/optics-device-captures-its-first-light.jpghttp://www.thetechnologylounge.com/wp-content/uploads/2017/08/optics-device-captures-its-first-light-150x150.jpgAmmanTech Newsoptics device captures its first light
The ESO's Very Large Telescope (VLT) fourth telescope (Yepun) has just been changed into a fully adaptive telescope. After more than a decade of planning construction and testing, the new Adaptive Optics (AOF) device captured its first light through the MUSE instrument, delivering incredibly resolute images of planetary nebulae...