ESO’s New Compact Laser Guide Star Unit Tested
22 June 2011
Last night, ESO’s Wendelstein laser guide star unit had its first light at the Allgäu Public Observatory in Ottobeuren, Germany. Laser guide stars are artificial stars created high up in the Earth’s atmosphere using a laser beam with a power of several watts. The laser, in this case a powerful 20 watt yellow beam (operating at 589 nm), makes the sodium atoms in a layer 90 kilometres up in the atmosphere glow and so creates an artificial star in the sky that can be observed by a telescope. The adaptive optics equipment can then use measurements of the artificial star to correct for the blurring effect of the atmosphere in the observations.
ESO has developed a concept for compact laser guide star units, whereby small powerful lasers are combined with a telescope that launches the beam, creating a single modular unit that can be mounted directly on a large telescope. This new approach solves several of the problems experienced with a number of the first generation laser guide star systems around the world, and has now been field-tested for the first time.
ESO has recently developed, patented, transferred to industry and licensed a new laser technology, a narrowband Raman fibre amplifier, with up to 50 watts of power, as well as designed laser guide star units for the VLT’s Adaptive Optics Facility. Four such laser guide star units will be installed on the VLT’s Yepun telescope in 2013. The laser guide star unit is also a core component for the generation of laser guide stars for the future European Extremely Large Telescope.
The ESO Technology Division Laser Systems Department has built the prototype Wendelstein laser guide star unit in collaboration with the companies Toptica, MPBC and Astelco to field test the concept and to perform experimental studies of the sodium layer high up in the atmosphere. This will pave the way for future telescope projects and optimise the way in which artificial laser guide stars are created.
The prototype unit will initially be used in conjunction with the Allgäu Public Observatory’s 0.6-metre telescope and its CCD camera. Various measurements will be taken during the summer of 2011 to start collecting scientific data and to validate the setup, before transferring the equipment to its final home at the Paranal Observatory, in northern Chile.
Domenico Bonaccini Calia
ESO Laser Systems Department
Tel: +49 89 3200 6567
Allgäu Public Observatory
Lars Lindberg Christensen
Head of ESO education and Public Outreach
ESO, Garching, Germany
Tel: +49 89 3200 6761
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