
Proceedings Paper
Manufacturing and testing of a convex aspherical mirror for ASSISTFormat | Member Price | Non-Member Price |
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Paper Abstract
ASSIST is the testbed for the ESO Adaptive Optics Facility. The main objective of ASSIST is the characterization of the
1.2 meter deformable mirror which will replace the existing secondary of one of the 8 meter VLT telescopes. A large
concave 1.65 meter diameter aspherical primary mirror combined with a 140 mm diameter convex aspherical secondary
forms the main optical system of ASSIST. Two additional optical units provide the light sources and the wave front
analyzing optics. Without having the possibility for checking the entire optical system as a whole, each individual mirror
had to be manufactured and tested using reliable techniques. The secondary mirror for ASSIST (AM2) is made of an
optically transparent material (BK7) with a specific and accurate backside radius in order to achieve a null test in
transmission. Furthermore, not only the overall RMS surface error of AM2 is important, but due to the fact that it will be
used in a setup that measures specific spatial frequencies, also the spatial frequencies of the surface error of AM2 is
important. The aspherical surface is tested in double pass using an optical flat and an interferometer with a transmission
sphere. Manufacturing of this asphere is mainly done by hand at the optical lab of NOVA-ASTRON. The final accuracy
of the reflecting surface is within the required 50 nm RMS with a surface roughness of less than 2 nm RMS. This paper
reports in more detail on manufacturing and testing of the a-spherical convex mirror.
Paper Details
Date Published: 13 September 2012
PDF: 11 pages
Proc. SPIE 8450, Modern Technologies in Space- and Ground-based Telescopes and Instrumentation II, 84504X (13 September 2012); doi: 10.1117/12.926126
Published in SPIE Proceedings Vol. 8450:
Modern Technologies in Space- and Ground-based Telescopes and Instrumentation II
Ramón Navarro; Colin R. Cunningham; Eric Prieto, Editor(s)
PDF: 11 pages
Proc. SPIE 8450, Modern Technologies in Space- and Ground-based Telescopes and Instrumentation II, 84504X (13 September 2012); doi: 10.1117/12.926126
Show Author Affiliations
Rik ter Horst, ASTRON (Netherlands)
Remko Stuik, Leiden Observatory, Leiden Univ. (Netherlands)
Published in SPIE Proceedings Vol. 8450:
Modern Technologies in Space- and Ground-based Telescopes and Instrumentation II
Ramón Navarro; Colin R. Cunningham; Eric Prieto, Editor(s)
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