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Proceedings Paper

Development of configurable slit unit for GTC-EMIR
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Paper Abstract

The Configurable Slit Unit (CSU) for EMIR shall enable the possibility to generate a multi-slit configuration, a long slit, or an imaging aperture at the entrance focal plane of the GTC-EMIR instrument. The CSU is therefore a cryogenic reconfigurable slit mechanism. It contains 100 sliding bars which can be positioned within the 307x307mm wide aperture of EMIR's instrument field of view. The development of the CSU has been a challenging task for several reasons: the high number of elements to control to configure a single observing pattern; the nominal working temperature of 77 K at which all the functionalities have to be accomplished, the stringent requirements in both accuracy and repeatability for most of the functionalities and the rotating nature of the EMIR instrument. The combination of these requirements urged the need to develop new pioneering concepts for actuation and position measurement. An actuation mechanism has been developed based on a piezo drive concept. A dedicated incremental, endless capacitive measurement system has been developed to measure the position of each separate bar. Both technologies are successfully realized in the demonstration programme that has been launched to prove the feasibility of the CSU concept. Besides actuation and position control of the bars, also thermal behavior of the CSU concept have been evaluated within the demonstration programme.

Paper Details

Date Published: 29 June 2006
PDF: 6 pages
Proc. SPIE 6269, Ground-based and Airborne Instrumentation for Astronomy, 62694B (29 June 2006); doi: 10.1117/12.671793
Show Author Affiliations
M. Teuwen, Janssen Precision Engineering BV (Netherlands)
H. Janssen, Janssen Precision Engineering BV (Netherlands)
R. Geurink, Janssen Precision Engineering BV (Netherlands)
P. Redondo, Instututo de Astrofisica de Canarias (Spain)
J. J. Díaz-Garcia, Instututo de Astrofisica de Canarias (Spain)

Published in SPIE Proceedings Vol. 6269:
Ground-based and Airborne Instrumentation for Astronomy
Ian S. McLean; Masanori Iye, Editor(s)

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