Annual Report 2011 Max Planck Institute for Astronomy

76 IV. Instrumental Developments and Projects
Cryostat for: L/M-Band (3 – 5 mm) N-Band (8 – 13 mm)
Cooler Pulse Tube Cooler (Cryomech PT 410)
Detector Hawai II RG 5 mm Raytheon Aquarius
Pixel / pixel size 2K3 2K/18mm 1K3 1 K / 30 mm
Cryostat: Size (h 3 w 3 l) / weight: 205 3 98 3 68 cm / 1500 kg
Temperature Detector / Optics 40K/40K 8K/40K
Temperature stability 0.1 K
Adjustable support (range / accuracy) 5 mm (in h, x, y) / 0.2 mm
Cool-down time < 3.5 days
Accessibility of cold optics / detector Accessible without dismounting the cryostat
Detector displacement from vibrations < 2 mm < 3.5 mm
Table IV.3.2: The main requirements for the two cryostats.
mized between the contradicting properties of a sufficient
cooling on the one hand and an efficient vibration
damping on the other side.
In addition to these tests we had to perform several calculations,
e.g. a Finite Element Analysis for the characterization
of damage-prevention against Paranal-typical
earth-quakes or the temperature distribution of the optics
during cool-down. Also a thorough hazard analysis
for the cryostat operation had to be delivered to eso.
Table IV.3.2 shows the main requirements for the two
cryostats.
In parallel we continued in finalizing the design of
the control electronics for the upcoming second part of
the FDR in April 2012. Because of the limited space
in the labs on Paranal a major effort had to flow into
a compact design of the electronics. The control of
70 motors and of a lot of additional devices had to be
packed into 3 cabinets.
Thomas Henning, Uwe Graser,
Werner Laun, Michael Lehmitz,
Marcus Mellein, Udo Neumann,
Vianak Naranjo