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Proceedings Paper

Use of a Faro Arm for optical alignment
Author(s): Lisa A. Crause; Darragh E. O'Donoghue; James E. O'Connor; Francois Strümpfer
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Paper Abstract

We discuss the use of a Faro Arm - a portable coordinate measuring machine - in the re-alignment and testing of the Southern African Large Telescope's Spherical Aberration Corrector. In pushing this versatile tool to its limits, we have arrived at a better understanding of its true capabilities and developed ways to compensate for some of its weaknesses. It is possible to achieve excellent results (~5 microns) when making relative measurements and keeping the Arm's orientation relatively constant. The Faro is also extremely useful in providing live feedback while making fine adjustments. However, single measurements of the same position are considerably less reliable (~50 microns) when the Arm is operated in widely different orientations. If the latter is unavoidable, one may largely counteract this by taking continuous streams of measurements (1000 readings) for a given point while exercising the Arm as much as possible in order to average the encoder errors. Various other techniques and accessories that we have found useful, as well as some painful lessons, are described here and a few examples are given to demonstrate how we have used a Faro Arm in our challenging optical alignment project.

Paper Details

Date Published: 23 July 2010
PDF: 10 pages
Proc. SPIE 7739, Modern Technologies in Space- and Ground-based Telescopes and Instrumentation, 77392S (23 July 2010); doi: 10.1117/12.856810
Show Author Affiliations
Lisa A. Crause, South African Astronomical Observatory (South Africa)
Darragh E. O'Donoghue, South African Astronomical Observatory (South Africa)
James E. O'Connor, South African Astronomical Observatory (South Africa)
Francois Strümpfer, South African Astronomical Observatory (South Africa)


Published in SPIE Proceedings Vol. 7739:
Modern Technologies in Space- and Ground-based Telescopes and Instrumentation
Eli Atad-Ettedgui; Dietrich Lemke, Editor(s)

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