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Sac Peak Workshop (1Dec92) (from NSO, NOAO Newsletter No. 32, 1 December 1992) The Real Time and Post-Facto Solar Image Correction workshop, held 15-18 September 1992, at Sac Peak, was the thirteenth in the series. The organizing committee consisted of R. Radick (Phillips Lab./Solar Research Branch, Sacramento Peak) (chair), R. Dunn (NSO), G. Loos (Phillips Lab./Imaging Technology Branch), S. Restaino (New Jersey Inst. of Tech.), and O. von der Lhe (European Southern Obs.). The workshop dealt with the current and perspective application of adaptive optics, deconvolution, and speckle techniques to high spatial resolution imaging. Because of growing recent interest in solar imaging using interferometric arrays, this topic was also included. There were about sixty participants, with twenty from thirteen foreign countries. A consensus emerged that a resolution of 10-20 km (a few hundredths of an arcsec) is required to adequately resolve small scale magnetic structures on the Sun. This is well beyond the capability of existing solar techniques, even with perfect atmospheric correction. Achieving such resolution will require the development of solar interferometers. It is time to start developing a second generation of solar correlation trackers, using contemporary components, that should be both faster and cheaper than existing devices. Phase diversity, which involves recovering phase from comparison of simultaneous in-focus and out-of-focus images, offers a potentially powerful method for phasing interferometric arrays, and for wavefront sensing for both real-time and post-facto imaging systems. It should also offer an attractive alternative for phase recovery in speckle imaging applications. Extended-field interferometry is feasible, especially for bright sources such as the Sun. Infrared seems attractive for technical as well as scientific reasons in solar interferometry. Existing large-aperture telescopes can be reconfigured using pupil masks to operate as solar IR interferometers. Heat rejection is feasible, thereby protecting such telescopes from damage due to solar exposure. Experiments on such telescopes would provide valuable experience in dealing with extended source solar interferometric data, and serve as a proof-of-concept for larger arrays that may eventually be built. Richard Radick
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