CELT
The University of California is studying concepts for the next generation
of large telescopes, and has proposed that the Keck-style segmented design
be applied to a 30 meter diameter telescope. The CELT (California
Extremely Large Telescope) is a design concept for the next generation
of very large optical/infrared telescopes. The CELT telescope can be summarized
as:
Status:
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30-m diameter primary mirror optical/infrared telescope
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1000-segmented mirror design with active control of the hyperbolic
surface figure
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3 x 1000 actuators on the primary mirror (tip, tilt & piston)
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~ 100 nm optical wavefront error budget
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4-m diameter (convex) secondary mirror
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The problems:
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Segment fabrication and testing (industrial scale of precision optics)
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Support of the mirror surface (few grams of Al)
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Precision positioning of mirror segments with long term stability
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Dynamic response of the structure to (turbulent) wind loading (CFD
problem)
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Consider for primary and secondary mirrors
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Adaptive optics control of atmospheric wavefront aberrations
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20,000 actuators, 40,000 wavefront measurements
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FFT, conjugate gradient & preconditioners
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Physical plant
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Site selection
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Long term site testing to find good transparency, low water vapor
and good seeing
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Computational fluid dynamics (CFD) problem: response of laminar flow to
topography, enclosure and telescope structure
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Climate modeling to understand long term viability of the site