Adhere Invar locating pins to grating, allow 24 hours to set and 48-72 hours to cure.
Assemble grating cell and prism cell with dummy optics.
Assemble MOE with dummy optics for fit check and trail installation.
Make modifications as necessary.
Assemble prism in cell.
Assemble grating in cell (after cure time).
Assemble MOE, install on DSS and test.
Make adjustments as necessary.
Report
MOE Installation
MOE optics mounting went smoothly. The threaded holes for mounting the matrix ring to the base plate were not tapped. A metric M10 x 1.5 tap couldn't be found.
There was an interference with the prism cell and the MOS. The MOE prism cell and uprights were modified to accomodate. Modifications involved relocating the prism and cell 11 mm lower along its mounting axis (central axis). This required removal of material (approximately a 10 mm chamfer) along the bottom edge of the cell for clearence with the wheel. One prism cell mounting screw hole was dropped due to this movement.
It appears that intereference is a result of a slight difference between manufacturing drawings and the manufactured part. The as-built is NOT as specified on the drawings. An extra tab of material exists 3/8" into the DSS cutout on the vertical box plates. Also, although not an issue here, a MOS shim extends further than expected which could cause problems.
MOE installation on the wheel should only be done fully assembled, but is very difficult. This interference results in a 3.5% loss due to vingetting, and 2 days lost to making modifications.
New uprights and a new prism cell could be fabricated to account for the above modifications.
Covers are needed for the prism and grating.
GTM Change Tool
Assembled but not tested as work was being conducted on the telescope and IR which prevented necessary access. Installation of the MOE lamps required power to be shutdown for several hours.
Other Issues - Future Work
The GTM setup table was not properly configured for the current mechanism arrangements. The tilt mechanisms were labelled in an effort to prevent this from happening in the future. The setup table was updated to reflect the current mechanism configurations. The setup table needs to be updated everytime gratings are swapped between mechanisms.
Suggested revisions to the setup tool include incorporating pulldowns which would 'remind' user of this issue.
DSS clamping issues were investigated, but the reported problem couldn't be repeated. The status of this issue remains 'under investigation'.
GTM calibrations should be checked and adjusted as necessary.
Look into Glycol plumbing options.
Look into quick release or 1/4 turn fasteners for the front panels to replace the current setup.
