CFHT operating manual - Homepage Usask

ESPaDOnS: picture gallery http://webast.ast.obs-mip.fr/magnetisme/espadons_new/gallery.html
detailed view of the calibration box containing flat-field and spectral reference (thorium) lamps; a
short optical fibre conveys light from the lamps (collected on the left edge of the calibration box) to the main Cassegrain
structure;
The spectrograph and enclosure
The spectrograph is the main module
of ESPaDOnS, both in cost and size.
The image on the right shows the
image slicer module with the slit
shutter (behind the small black disc
in the middle) corresponding to
where the photons are injected within
the spectrograph; after a first pass on
the main collimator (not visible on
this image), the beam is dispersed
vertically by the grating (on the right
side of the image) before passing a
second time on the main collimator; a
first spectrum (running vertically)
with all orders overlapping (no cross
dispersion) is formed close to the flat
mirror (visible at the immediate left
of the slit shutter) before being
reflected off to the other side of the
spectrograph (transfer collimator,
prism train, camera and dewar, all
hiding behind the large black baffles
visible on the left side of the image).
Selected images of individual
components are presented below:
detailed view of the electronic rack containing all control harware for the Cassegrain module.
close-up view of the image slicer bench, showing the fibre bundle (on the left) bringing photons
from the Cassegrain module along with the manual and motorised newport stages (both translation and rotation) for
positionning the fibre and dedicated optics (three reimaging triplets plus a field doublet lens) with respect to the
rotatable image slicer (hiding behind the central newport stage);
detailed view of the main collimator mirror, cut off (along with the transfer collimator) from a
parent parabolic mirror of 68cm diameter; the exposure meter (picking off a very small amount of light from the main
beam in its way from the main collimator to the grating) is also visible in the foreground;
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