Publications of the MPIfR
Optical & Infrared
Interferometry Group
Udo Beckmann, Jan Behrend, Hermann
Bohnhardt, Claus Connot, Thomas M. Driebe, Matthias Heininger, Thomas
M. Herbst, Karl-Heinz Hofmann, Edmund Nussbaum, Dieter Schertl, Walter
Solscheid, Christian Straubmeier, and Gerd P. Weigelt
The fringe and flexure tracking detector of the
LBT LINC-NIRVANA beam-combiner instrument
New Frontiers in Stellar Interferometry,
Proceedings of SPIE Volume 5491.
Edited by Wesley A. Traub. Bellingham, WA: The International Society
for Optical Engineering, 2004., p.1445-1453
Abstract
LINC-NIRVANA is a near-ýinfrared (1-ý2.4 micron)
beam-ýcombiner instrument for the Large Binocular Telescope
(LBT). LINC-NIRVANA is being built by a consortium of
groups at the Max-ýPlanck-ýInstitut fur Astronomie in Heidelberg, the
Osservatorio Astrofisico di Arcetri in Florence, the Universitat
zu Koln, and the Max-ýPlanck-ýInstitut fur Radioastronomie
in Bonn. The MPI fur Radioastronomie is responsible for the
nearý-infrared detector for the fringe and flexure tracking
system (FFTS). We describe the design and construction of
the detector control electronics as well as the first
laboratory measurements of performance parameters of the NIR detector
for the fringe and flexure tracking system of the LBT LINC-NIRVANA
instrument. This detector has to record LBT interferograms of suitable
reference stars in the FOV at a frame rate of the order of
200 frames per second using, for example, 32 x 32-ýpixel
subframes. Moreover, special noise reduction techniques have
to be applied. The fringe-ýtracker interferograms are required for
monitoring and closed-ýloop correction of the atmospheric optical
path difference of the two LBT wavefronts (see C.
Straubmeier et al., "A fringe and flexure tracking system
for LINC-NIRVANA: basic design and principle of
operation"). We will describe our laboratory measurements of
maximum frame rate, readout noise, photometric stability, and other
important parameters together with first measurements of
laboratory simulations of LBT interferograms.
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