IMACS Engineering Run, Mar 25 - April 2, 2008

IMACS Engineering Run, Mar 25 - April 2, 2008
Tasks
Personnel and Observatory Support Required
Report

Tasks

Mosaic2 Installation

Reassemble ccd/platen in camera
Install Cryotiger compressors and lines
Electronics - ABS box modifications
Cold tests and comissioning
Map out coolant plumbing

S09 / Image Corrections

Continue to improve images (reduce tilt, coma, astigmatism) at f/2 by manipulating position of s09 in the camera and tilting the dewar.

GISMO

Delivered fold mirror plate.
Install cable retraction spring.

Miscellaneous Maintenance and Other Work

Install Slit Mask clamp assembly hardware.
Install new SH Guider linear bearings.

Personnel and Observatory Support Required

SBS

Alan Dressler
Christoph Birk
Greg Burley
Ian Thompson
Tyson Hare

LCO

Instrument Specialist
Machinist

Report

Electronics Upgrade / ABS Box Modification

Electronics Upgrade / ABS Box modifications proved troublesome and required more effort then planned for.
Modifications, as outlined by Alan B. were not possible, primarily due to space constraints.
Luckily the original PI Controller Chassis was populated with 2 E503 back planes that allowed for installation of both PI control hardware. The second PI control chassis should be copied to match this layout.
One Omega controller arrived with a broken retaining clip. The result was that the controller does not sit flush against the panel.
Communication with the new PI controller was not established once intsalled, even thought this was tested successfully in the lab. The work around was to leave the controller powered up with the servo control toggle switch in the 'on' position to close the internal loop, making the stage stiff.
The LVDT cable was found to have been fabricated with pinout errors on 3 of 5 pins. The result was an error in reported step resolution and stroke. Once the problem was tacked down and repaired the LVDT was found to be functioning properly, as tested in the lab.
The newly purchased vacuum gauge controllers were found to be incompatible with the installed wiring. Specifically the new devices use a different communication protocol (serial vs RS232). The older models were installed (original and spare).
Heat exchangers seem oversized for current setup now that three variacs have been removed.
New connector/adapters prevent the lid from closing. The lid was hinged on one edge and taped to the box. This makes access to the electronics inside very akward. Further, more work needs to be done on the cable pass throughs, more material would need to be removed so that the lid could properly close (without other connector issues).
A redesign of the layout should be considered. Currently the layout is quite tight due to the rearrangement needed to fit everything needed for the new f/2 dewar. Specifically, the one bulkhead and inner back plate are cause for concern as many of the devices on the newly installed panel seem to be tightly pressed against many cables and the coolant lines at the bulkhead. At the very least a new, deeper lid is needed to properly close the box.

Mosaic2 Installation

Delivery of Mosaic2 was delayed due to issues with shipment. Specifically, home supplies were included with the shipment causing the Chilean customs authorities to hold the shipment in Santiago for inspection.
The Cryotiger compressors and hoses were already installed when the IMACS team arrived. After several days in operation the compressors settled in at 30 - 40 psi.
Several iterations and hours were needed to level the focal plane assembly in a satisfactory configuration. This process tool longer than expected, but the exercise was instructive as to the mechanical performance of the platen itself. A fea analysis of the platen is needed to confirm predictions.
The Delrin bezel was modified to the smallest dimension possible to allow for future S09 piston and dewar postion movement
New shim plates are needed for both the nominal and tilted setups.
The LVDT cable was found to have been fabricated with pinout errors on 3 of 5 pins. The result was an error in reported step resolution and stroke. Once the problem was tacked down and repaired the LVDT was found to be functioning properly, as tested in the lab. The new focus range was measured to be 4.6 mm.
The dewar seems to hold a vacuum well. The ion pump was activated once cold and after being on the large Varian pump for several hours. The voltage levels and pressure were monitored and indicated all was functioning as expected.
Noise issues were observed and resulted in many hours of investigations. Although the source was not completely known or understood, switching to an external power supply and cable seemed to provide favorable results. The interesting issue is that the noise seen in the new e2v mosaic was not similarly observered with the site mosaic. Dark current was measuered to be 4 - 5 e- and investigations continue.

S09 / Image Corrections

Image correction resulted in sub 2 pixel images FWHM across the field with significantly reduced contributions from tilt, coma, and astigmatism.
Currently S09 is shimmed 1.75 mm (from nominal) toward the camera. This is equivalent to using 1.75 mm (.070") shims from the mounting/shimming surface.
S09 was also translated to to the right 1.0mm and up 0.5 mm (-1.0mm, 0.5mm) when looking toward the instrument along the optical axis, with the instrument in the IMACS home position (NIR @ -46.05º)
Tilt corrections were made by shimming the dewar in the following configuration; .005" shim under upper right corner, .040" shim under upper left corner, .035" shim under lower left corner (with instrument at IMACS home position). After examining the data for this configuration is was suggested that one more iteration could be attempted where .005" of shim was removed from the left side.

SMS Latch Installation

Installed plumbing and hardware, logic and limit switches test and confirmed to be workinf as expected. The hardware mounting plate needs to be revised and refabed due to space issues and fabrication errors.
Configured and tested software lockouts at engrgui level.
Latch will be left in the open position for all masks (excluding GISMO) until all mask wings are modified with cutout. this results in reduced acquisiton field (temporary) for the Principal Guide Camera of approx. 3.5 degrees.
Six new mask wings will be fabricated at SBS. The exchange cycle is expected to last three months.

GISMO

Time constraints prevented installation of GISMO for the purposes of configuring the cable retraction spring.

Miscellaneous Maintenance and Other Work

Delivered repaired Linmot E1000 controller for Gismo spare.
Delivered spare focus motors
Measured mechanical storage cabinet dimensions for plastic storage boxes

General Notes

Thanks to the mountain staff for their assistance in our successful run.
Required Parts

revised SMS pneumatics mount plate
order tool/screw chests
order storage boxes

Future Work

establish communication with the f/2 PI controller
generate flexure map
plumb new dewar cooling system
install and configure GISMO cable return spring