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15 July 2010 Submillimeter pupil-plane wavefront sensing
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The goal of a large (25 m) submillimeter telescope with high aperture efficiencies up to frequencies of ~ 1 THz requires a wavefront sensor able to measure the telescope surface figure to an accuracy of order 1 micron, better than has been achieved to date in the millimeter/submillimeter (MSM) regime. On the other hand, the recent availability of largeformat submillimeter detector arrays suggests that new techniques can be applied. In particular, using submillimeter focal plane arrays, variants of interferometric pupil-plane wavefront sensing techniques familiar from the optical/infrared (OIR) regime could perhaps be applied profitably in the MSM. However, while many possibilities can in principle be considered, many of these possibilities would be unwieldy in the MSM, because of the need for large off-axis reflective optical elements, and the consequent sizeable optical layout. However, the overall size of an interferometer can be minimized by making use of a common-path interferometer. Here we thus consider the applicability to MSM wavefront sensing of a rather simple common-path pupil-plane interferometer, specifically a scanning version of the fixed-phase phase-contrast interferometers described in different contexts by Zernicke1 and Dicke2. Both transmissive and reflective solutions for the needed phase shifting interferometers are possible, but here we focus on the reflective case as a proof of principle. Such a common-path phase-shifting interferometer has several potential advantages: relative simplicity, compactness, ease of manufacturability, reduced systematic effects, and high accuracy.
© (2010) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
E. Serabyn and J. K. Wallace "Submillimeter pupil-plane wavefront sensing", Proc. SPIE 7741, Millimeter, Submillimeter, and Far-Infrared Detectors and Instrumentation for Astronomy V, 77410U (15 July 2010);


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