Next generation of wide field adaptive optics




Stoesz, Jeffrey A.

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In the last decade, adaptive optics systems have been implemented on all the major ground based telescopes and have proven reliable tools for correcting the image to near the diffraction limit. However, the correction from these systems is limited to a narrow field of view. This dissertation address the challenges of widening the corrected field of single conjugate adaptive optics by properly using statistical information on the optical turbulence profile of the atmosphere above the telescope, and by optimizing the trade-off between image quality and field of view. Altair is the facility adaptive optics system for the 8-meter Gemini North telescope and marks the historical beginning of wide field adaptive optics. Its performance evaluation in Part One is the first on-sky comparison of sparse field images from an altitude-conjugated and a ground-conjugated deformable mirror. All of the other basic aspects of Altair's performance are characterized for use by the Gemini community to plan observations. We also study and report. on techniques for extrapolating the edge of the deformable mirror, a critical step in altitude-conjugated mode. In Part Two we develop a point spread function model for Ground Layer Adaptive Optics (GLAO) that is based on analytic forms of the phase power spectral density. This model has been used for feasibility studies of GLAO on Gemini, and the Thirty Meter Telescope (TMT), currently the most advanced extremely large telescope project. The TMT will be an adaptive telescope that has science goals for the huge 81 square arcminute field of the Wide Field Optical Spectrograph (WFOS). We will show that WFOS-GLAO provides useful gains and will operate in the very wide GLAO (VWGLAO) regime, which has no additional overhead for seeing improved operation. To identify the VWGLAO regime we use statistical turbulence profile models and examine anisoplanatism in terms of image quality metrics relevant to the science that GLAO will likely assist. The VWGLAO regime is where there are useful gains over the theoretical seeing limit for wide field science that measure data collection efficiency as proportional to the product of image quality and the field of view (solid angle). We also show that for many cases VWGLAO will not be impacted by lag anisoplanatism nor by wavefront sensor noise.



adaptive optics, large astronomical telescopes