12 September 2012 The cryostat for the GRAVITY beam combiner instrument at the VLTI
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GRAVITY is a second generation VLTI instrument for high-precision narrow-angle astrometry and phase-referenced interferometric imaging in the astronomical K-band. The cryostat of the beam combiner instrument provides the required temperatures for the various subunits ranging from 40K to 290K with a milli-Kelvin temperature stability for some selected units. The bath cryostat is cooled with liquid nitrogen and makes use of the exhaust gas to cool the main optical bench to an intermediate temperature of 240K. The fringe tracking detector will be cooled separately by a single-stage pulse tube cooler to a temperature of 40K. The pulse tube cooler is optimized for minimum vibrations. In particular its warm side is connected to the 80K reservoir of the LN2 cryostat to minimize the required input power. All temperature levels are actively stabilized by electric heaters. The cold bench is supported separately from the vacuum vessel and the liquid nitrogen reservoir to minimize the transfer of acoustic noise onto the instrument.
© (2012) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
M. Haug, F. Haussmann, S. Kellner, R. Hofmann, J. Eder, F. Eisenhauer, J.-L. Lizon, G. Thummes, H. Weisz, "The cryostat for the GRAVITY beam combiner instrument at the VLTI", Proc. SPIE 8445, Optical and Infrared Interferometry III, 84452V (12 September 2012); doi: 10.1117/12.925312; https://doi.org/10.1117/12.925312


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