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30 January 2003 Optics for the 20/20 telescope
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We present a plan for making the optics of a 21 m telescope that builds on advances in mirror design and fabrication developed for the Large Binocular Telescope and other large telescopes. The 21 m telescope, with a fast f/0.7 primary mirror made of only seven large honeycomb-sandwich segments and an adaptive secondary mirror with matching segments, is much stiffer than other designs and offers simpler and more accurate wavefront control. It can be a powerful stand-alone telescope, or one of a pair that move on a circular track to achieve coherent imaging with baselines up to 120 m (the 20/20 telescope). Each segment of the 21 m primary mirror is similar to an 8.4 m LBT primary, and each segment of the 2.1 m adaptive secondary mirror is similar to an LBT secondary. The off-axis segments of both mirrors can be made with the same methods and equipment currently used at the Steward Observatory Mirror Lab, and can be polished with the same stressed-lap polishing system used for the LBT mirrors. A change in algorithm to accommodate the asymmetric surface is required, but no new hardware development is needed because the lap bending is similar to that for the LBT mirrors. Each segment can be measured interferometrically, with a combination reflective and diffractive null corrector producing an accurate template wavefront and alignment references for the segments.
© (2003) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
Hubert M. Martin, James Roger P. Angel, James H. Burge, Stephen M. Miller III, Jose M. Sasian, and Peter A. Strittmatter "Optics for the 20/20 telescope", Proc. SPIE 4840, Future Giant Telescopes, (30 January 2003);


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