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23 September 2015 Optical and mechanical design and characterization of the new baffle for the 2.4-m Thai National Telescope
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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.
© (2015) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
Christophe Buisset, Apirat Prasit, Thierry Lépine, and Saran Poshyajinda "Optical and mechanical design and characterization of the new baffle for the 2.4-m Thai National Telescope", Proc. SPIE 9626, Optical Systems Design 2015: Optical Design and Engineering VI, 96262F (23 September 2015);


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