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Proceedings Paper

Optical and mechanical design and characterization of the new baffle for the 2.4-m Thai National Telescope
Author(s): Christophe Buisset; Apirat Prasit; Thierry Lépine; Saran Poshyajinda
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Paper Abstract

The first astronomical images obtained at the 2.4 m Thai National Telescope (TNT) during observations in bright moon conditions were contaminated by high levels of light scattered by the telescope structure. We identified that the origins of this scattered light were the M3 folding mirror baffle and the tube placed inside the fork between the M3 and the M4 mirrors. We thus decided to design and install a new baffle. In a first step, we calculated the optical and mechanical inputs needed to define the baffle optical design. These inputs were: the maximum length of the baffle, the maximum dimensions of the vanes and the incident beam diameter between M3 and M4 mirrors. In a second step, we defined the number, the position and the diameter of the vanes to remove the critical objects from the detector's FOV by using a targeted method. Then, we verified that the critical objects were moved away from the detector’s view. In a third step, we designed and manufactured the baffle. The mechanical design is made of 21 sections (1 section for each vane) and comprises an innovative mechanism for the adjustment of the baffle position. The baffle installation and adjustment is performed in less than 20 minutes by 2 operators. In a fourth step, we installed and characterized the baffle by using a pinhole camera. We quantified the performance improvement and we identified the baffle areas at the origin of the residual stray light signal. Finally, we performed targeted on-sky observations to test the baffle in real conditions.

Paper Details

Date Published: 23 September 2015
PDF: 13 pages
Proc. SPIE 9626, Optical Systems Design 2015: Optical Design and Engineering VI, 96262F (23 September 2015); doi: 10.1117/12.2190509
Show Author Affiliations
Christophe Buisset, National Astronomical Research Institute of Thailand (Thailand)
Apirat Prasit, National Astronomical Research Institute of Thailand (Thailand)
Thierry Lépine, Lab. Hubert Curien (France)
Saran Poshyajinda, National Astronomical Research Institute of Thailand (Thailand)

Published in SPIE Proceedings Vol. 9626:
Optical Systems Design 2015: Optical Design and Engineering VI
Laurent Mazuray; Rolf Wartmann; Andrew P. Wood, Editor(s)

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