The European LGS Test Facility

A European Laser Guide Star (LGS) test facility is proposed for the 4.2m William Herschel Telescope (WHT) on La Palma. It will test the next-generation Adaptive Optics (AO) LGS technologies to aid risk mitigation of Extremely Large Telescope (ELT) LGS AO systems. In particular, critical scaling of current LGS AO technologies to ELT dimensions will be tested. For example, experiments addressing increased spot elongation, cone effect and the order of correction required. A pan-European consortium proposes to construct test facility infrastructure on the WHT for a number of risk mitigating experiments. The infrastructure includes the construction of a Nasmyth platform based controlled environment 'Ground-based Adaptive optics Innovative Laboratory' (GRAIL), an experimental test environment 'Testbed integration facility' (TIF) and some common-experiment equipment such as the Common Re-Imaging AO System. Experiments that are proposed for this facility cover the areas of laser technologies, spot elongation, LGS wavefront sensing, parallel launch concepts, Multi-Object AO, atmospheric characterisation, co-phasing and real-time control system risk mitigation.