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Proceedings Paper

Cryo design for the VLTI MIDI instrument
Author(s): Ralf-Rainer Rohloff; Werner Laun; Uwe Graser; Norbert Ortlieb; Matthias Lebong
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Paper Abstract

The paper describes the cryogenic design of the 8 - 12 micrometers beamcombiner instrument MIDI for the VLTI. Because the instrument is very sensitive at the whole thermal wavelength region, all optics and mechanics inside the dewar have to be cooled to temperatures at 40 K. The main contribution to the heat load is the radiation. We propose to use one liquid Nitrogen cooled radiation shield and a second shield cooled by the first stage of a closed cycle cooler with a refrigeration capacity of 35 W at 50 K and 1.5 W at 4.2 K. The main problems by using a closed cycle cooler are the vibrations which can disturb the interferometric measurements. We measured the vibrations during cooler operation and checked different vibration isolation possibilities.

Paper Details

Date Published: 5 July 2000
PDF: 12 pages
Proc. SPIE 4006, Interferometry in Optical Astronomy, (5 July 2000); doi: 10.1117/12.390219
Show Author Affiliations
Ralf-Rainer Rohloff, Max-Planck-Institut fuer Astronomie (Germany)
Werner Laun, Max-Planck-Institut fuer Astronomie (Germany)
Uwe Graser, Max-Planck-Institut fuer Astronomie (Germany)
Norbert Ortlieb, Max-Planck-Institut fuer Astronomie (Germany)
Matthias Lebong, Max-Planck-Institut fuer Astronomie (Germany)


Published in SPIE Proceedings Vol. 4006:
Interferometry in Optical Astronomy
Pierre J. Lena; Andreas Quirrenbach, Editor(s)

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