IMACS final integration and assembly

Installation of structure light baffles

The baffle between the field lens (left, big end of cone) and the collimator
barrel is now installed.  The large black cover at the upper left seals the area around
the mask server.  The slit area is exposed to telescope air - the rest of the instrument
is sealed at the field lens.  Barbell weights near the center of the image are ballast,
to rotationally balance the structure.

The FOSS disc is made air and light-tight by a set of PVC plastic
covers which show up here slightly darker than the "IMACS Grey"

Installation of the IMACS short camera

First, the short camera has to be threaded into the structure,
between the utility wrap and the mainframe.

Tyson Hare installing the camera counterweight mount.

Front of the short camera on the way in.

Weights installed.

Inserting the camera in the MOSS structure.

Bigelow butts in...





Short camera seen from the telescope focus.


Front of short camera peeking out from behind the disperser server.



Steve Gunnels lends a hand attaching the dewar to the dewar installation too.


Bigelow can't help himself and butts in again...


Front view of the 8K array.


Ian Thompson guides $500K of silicon toward the short camera.


Close up of the 8K array.

Dewar installed!


IMACS as it appeared on 1/13/03.  Note that the utility wrap (center-right) is now installed, as are
the hoses for liquid cooling and air (blue), and Cryotiger coolant lines (silver).

IMACS side view.  Note enclosure panels mounted in slit area (far left).  The collimator,
f/4 camera, and its filter server can be seen in the center of the instrument.

A laser-cut slit mask with about 650 cross patterns for image testing, mounted on the mask server.
Each cross is made up of 4 small slits and a round central hole.  This mask took about 3 hours of
machine time on the laser mask cutter.


IMACS as it appeared for the OCIW open house in late October.  Note that the dewar is mounted on
the short camera barrel at the extreme right in this image.  The long camera with its shutter and
filter server can be seen in the lower middle of the image.  The slit mask server and field lens can
be seen at the far left.

View of the slit area.  A slit mask is shown in the center of the image.  Below the mask,
the principal guide camera is shown.  To the left of the mask is the mask shuttle, holding
additional (test) slit masks.  At the far right, the center field guide camera can be seen.

The field lens is shown with cross hairs used for alignment of the lens and the mask transfer system.

Field lens shown with slit mask retracted.  Center field guider at right.

Alan Baggish and Christoph Birk with the IMACS utility wrap.  The carrier is
an IGUS chain.  The flexible part of the wrap is about 13 feet long, and the
cable length (racks to instrument bulkhead) is about 35 feet long.

The utility wrap structure.  The grey ring guides and supports the moving portion of the utility wrap.
The black inner section defines the inner radius for the wrap, and includes a pass-through to the
instrument bulkhead (shown at the 7:00 position).


The dewar now has 8 detectors installed, and both cryotigers are now
installed and operational.  Black structure at right is the rotating support
for the IGUS utility chain.  The fixed IGUS support is being re-worked at
Rettig.  Note that the front enclosure panels are finished and installed.
Work continues with installation of the middle and rear panels.

Rear quarter view...




First light with Science Array!

First light image taken with one of four CCDs currently installed in the IMACS
science array.  The spots are images of 0.5 arcsec holes, on 1 arcmin centers,
on a laser-cut testing slitmask.   The origin of the shadow has not yet been

A single spot, showing most of the energy concentrated in 3-4 0.11 arcsec pixels,
taken from the image above.  Note that the holes in the slit mask are not perfectly
round, and make a contribution to the shape of the spot.

The dewar mounted on the back of the long camera.  Note that only one cryotiger
was installed for the first light exercise - the second cooling head was damaged
and returned to APD for repair.  The shutter can be seen mounted in the camera
behind the dewar.


Latest flexure map.  Note that the hysteresis seen in the earlier map is almost completely
gone now.  The source(s) of this flexure is still not completely understood, although some
of it is almost certainly due to major (temporary) imbalances in the structure.  The hysteresis
seen in the previous image was probably due to loose lens assemblies in the collimator.


First flexure map!  The data shown in the plot below was taken with a guide camera
located at the long camera focus, as the instrument structure was rotated in 30 degree
increments up to 240 degrees, and then back to the starting point.  Note that the instument
structure is not yet balanced.  In any case, at this early stage of final assembly, instrument
flexure is already within the range of the flexure control system (+/- 100 microns), and should
only improve as the remaining sub-assemblies balance the loads on the structure.



First Light!  The field lens, collimator, imaging mirror, and long camera have all been installed, and first light images have been taken with a guide camera located at the focus of the long camera.  We have seen 0.5 arcsec images of 0.5 arcsec slits on axis.  Preliminary flexure measurents show about +/- 10 px of flexure for a 180 degree rotation of the instrument.  As the long camera was not loaded with the 50Kg dewar, and the structure is not fully loaded with the short camera and disperser server, AND the optical assemblies have not been assembled with all fasteners (!), we expect the flexure numbers to improve dramatically as balance improves with final assembly.  Nevertheless, we are happy with these early numbers!




The aluminum plate at the rear of the MOSS is an adapter for mounting a Davidson D-275 alignment telescope.  The D-275 will be used to define the main optical axis, to which the slit masks and field lens will be aligned.  The recently modified trolley crane (note new cross beam at top) is being used to load the heavy items.

4/5/02 - End view of the instrument.

4/5/02 - The collimator can be seen, partly covered by a temporary baffle, and inserted in the MOSS.

4/5/02 - The slit mask server installed on the FOSS.