Adaptive Optics for Large Telescopes

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The next-generation of extremely-large ground-based telescopes (ELTs) will provide a huge leap in scientific capability and discovery potential. With adaptive optics, these telescopes will provide three times the resolution and as much as 100 times the sensitivity of the current ground-based and space telescopes opening new frontiers in fields ranging from the study of extra-solar planetary systems to the first objects forming in the distant Universe. As a partner in the Thirty Meter Telescope (TMT) Canadians will benefit directly from these advanced capabilities. Adaptive optics (AO), is key to the performance of all future large ground-based telescopes because it provides the means to cancel the blurring effect of atmospheric turbulence. Current AO systems are already providing impressive gains in resolution and sensitivity. The next-generation AO systems will require high-powered lasers and highly-sophisticated electromechanical and control systems. The lasers are used to illuminate sodium atoms in the upper atmosphere in order to produce artificial laser guide stars. These are used to sense the instantaneous distortion produced by the atmosphere, allowing the AO system to compensate for it. In developing these systems, it is essential to understand and characterize the distribution of sodium atoms. By equipping the 6-metre Large Zenith Telescope (LZT) with a pulsed laser and sensitive detector system, we have developed a sodium lidar (laser radar) system that produces data of unprecedented resolution and quality. I will use this facility to study and better understand the structure and dynamics of this important region of the atmosphere, and provide critical data that are needed for the design of the adaptive optics systems for extremely large telescopes. The LZT lidar facility also provides a unique opportunity to support the development of the AO lasers needed by the ELT projects. Such lasers must meet exacting requirements of power, beam quality, stability and efficiency. Their development requires an ongoing program of testing, evaluation and verification. At the LZT lidar facility, we are able to accurately measure properties of the laser and its launch telescope, such as the brightness and sharpness of the laser guide star. At the same time, the lidar provides simultaneous information about the abundance and distribution of sodium atoms. This allows the efficiency of the laser to be determined. This research program will support testing not only of lasers being considered for the TMT, but also for the European ELT. Canadians are participating, with the Université de Liège in Belgium and the Arayabhatta Research Institute of Observational Sciences in India, in a project to place a dedicated survey telescope at a Devesthal Peak in the Himalayas. The International Liquid-Mirror Telescope is a zenith-pointing 4-m telescope equipped with a 16-megapixel imaging camera. It will survey the strip of sky passing overhead night after night, searching for transient events such as supernovae and monitoring the variability of gravitational lenses. The design of the ILMT draws upon Canadian technology developed at the Université Laval and UBC and perfected with the LZT. I plan to assist with the commissioning and testing of the ILMT and participate in its scientific programs.