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Proceedings Paper

Active surface segmentation analysis of CCAT
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Paper Abstract

The Cornell Caltech Atacama Sub-millimeter Telescope (CCAT) is proposed to have 25m-diameter primary segmented active surface capable of diffraction-limited operation in the wavelength range between 200 microns to 1mm. The active surface design layout is composed of 162 "pie-shaped" segments, each fitted with three actuators that provide piston and tilt/tip control for segment positioning and orientation. We present a performance analysis for five types of segment positioning errors, e.g., piston, tilt/tips, radial and azimuth displacements, and twist errors. From these only the first two, segment piston and tilt/tip errors, are directly controllable by the actuator system. Segment tilt/tip motions may indirectly compensate radial and azimuth segment positioning errors. Residual segment twists introduce quadric phase distribution errors across the face of the segments that cannot be compensated by a simple 3-actuator/segment active surface control system. We have obtained Ruze's coefficients that relate the standard deviation of each segment positioning error type with the overall Strehl ratio of the telescope at 200 microns.

Paper Details

Date Published: 23 June 2006
PDF: 11 pages
Proc. SPIE 6267, Ground-based and Airborne Telescopes, 62672X (23 June 2006); doi: 10.1117/12.670312
Show Author Affiliations
Germán Cortés-Medellín, Cornell Univ. (United States)

Published in SPIE Proceedings Vol. 6267:
Ground-based and Airborne Telescopes
Larry M. Stepp, Editor(s)

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