Paper: astro-ph/0511572
Date: Fri, 18 Nov 2005 18:04:05 GMT (346kb)

Title: Chromaticity in all-reflective telescopes for astrometry

Authors: D. Busonero (1 and 2), M. Gai (1), D. Gardiol (1), M. G. Lattanzi (1),
D. Loreggia (1) ((1) INAF-Astronomical Observatory of Turin, Pino Torinese,
Torino, Italy, (2)University of Siena, Department of Physics, Siena, Italy)

Comments: 10 pages, 8 figures
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Chromatic effects are usually associated with refractive optics, so
reflective telescopes are assumed to be free from them. We show that
all-reflective optics still bears significant levels of such perturbations,
which is especially critical to modern micro-arcsecond astrometric experiments.
We analyze the image formation and measurement process to derive a precise
definition of the chromatic variation of the image position, and we evaluate
the key aspects of optical design with respect to chromaticity. The fundamental
requirement related to chromaticity is the symmetry of the optical design and
of the wavefront errors. Finally, we address some optical engineering issues,
such as manufacturing and alignment, providing recommendations to minimize the
degradation that chromaticity introduces into astrometry.

\\ ( http://arXiv.org/abs/astro-ph/0511572 , 346kb)