Max Planck Institute for Astronomy - Annual Report 2007

94 IV. Instrumental Developments and Projects
Fig. IV.1.3: Lucifer in the MPIA’s experimentation hall during
the integration phase: The upper crystal portion is just being
removed, the cold structure surrounded by super-insulation foil
inside is becoming visible. The telescope simulator is in the
background.
Fig. IV.1.4: The cable routing in the cryostat can be freely seen
through the open flange for the cable bushings.
transmitted to the wave front sensor and serves as the
control signal for the adaptive optics.
In order to limit the space required by the entire
system, the triple lens collimator which follows in the
beam path is pleated with the help of three flat mirrors.
The pupil plane in the collimated beam path coincides
with the plane of the grating (or of the folding mirror).
The subsequent camera systems are housed on a wheel,
thus making it possible to choose between three different
image scales. While the f/30 camera is a cassegrain
system with dual lens corrector, the two faster cameras
are pure lens systems.
The detector is a Hawaii-II type with 2048 2048 18-
µm pixels. The focus position can be corrected during
operations. The 1.8, 3.75, and 30 aperture ratio provide
0.25, 0.12, and 0.015 arc seconds per pixel imaging scales,
respectively.
28 filters can be positioned on two filter wheels. The
filter wheels are located on the convergent optical path
in front of the detector (see Fig. IV.1.2). At present eight
narrow band and ten wide band filters are designed for
both Lucifer instruments.
The Calibration Unit
For calibration purposes, a unit can be swung in front
of the cryostat window which images the light from a
calibration lamp emanating from an Ulbricht integrating
sphere. Both a broadband lamp for the calibration of the
camera and a gas discharge lamp for the calibration of
wavelengths are available here.
The Cryostat
The entire optics, including the telescope’s focal plane,
are cooled in a cryostat to around 70 K. The cryostat’s
housing is a lightweight stainless steel construction (see
Fig. IV.1.3). All supply openings such as plug flange,
CCC cooler, vacuum connections, and in- and outflow of