The Ohio State University College of Mathematical & Physical Sciences Department of Astronomy

Attendees: Tom O'Brien, Mark Derwent, Dan Pappalardo, Ray Gonzalez, Jerry Mason, Ed Teiga, Jason Eastman, & Rick Pogge

MODS Electronics

Dan reports that the Calibration/AGW Stage interlock is not done yet, they got delayed by having the wrong relay socket. New parts came in and they can start back in tomorrow. Ed has completed the special interlock cable. He expects to have the system taped and tested by the end of the week.

The integrating sphere lamps and mounting fixtures have been dug out of storage and are in Dan's office. Dan and Rick need to review the requirements for the lamp power supplies, which is up for design work next week.

MODS Mechanical Systems

Mark reported on work with installing the calibration system on MODS1. He revisited the baffle tube hardware and assembled the system on the structure in the shop. He aligned the baffle tube with the calibration tower. A new shim was required to complete the alignment, and they opted to create a castable shim. This is done and all cleaned up. The next steps is to install the baffle tube mating bellows after verifying the shim is correct. The next job up for Mark is to finish the MicroLYNX programming for the calibration tower insert/retract motion and pass this along to Ray for incorporation in the Instrument Control System.

In Enclosure work, Mark is finishing up the order for the MODS1 enclosure framing components. Item has promised us a 2-3 day (!) turn-around time for all of the framework and hardware. Mark is waiting until the frame hardware is in hand before making up the order for the side paneling so he can make sure the measurements are exact. The bill of materials and CAD drawings are all complete and uptodate. They decided to do the details of the access ports on the fly. We are only ordering the parts for MODS1 at this time, and once we have experience assembling that, we will order the parts (modulo any rework we discover) for MODS2. A second hoist has been ordered for the west-campus facility to help handling the full-size enclosure parts, as it was clear a single hoist rigging was non-optimal.

Justin Randles, an undergraduate, will be starting to work on June 13 with us. Mark will be his immediate supervisor, and he will be assisting Dave Steinbrecher for the summer on the MODS1 enclosure assembly.

Optics

Ross reports that SOML has made significant progress on removing the big bumps in the red corrector lens. Ross showed his analysis of before and after CMM measurements after 3 rubbing runs based on his earlier surface "hit map". Overall, about 3-microns of material were successfully removed in the high spots, giving a peak-to-valley variation of about 6-microns across the entire surface, though significant structure remains (e.g. the wedge and some low spots known from the previous full-aperture CMM maps). A fourth rub is in progress near the center of the part not touched during the previous 3 rubbing runs. We await the results.

It is clear that the measuring strategy is much improved, and Ross continues to work with SOML to assist in this effort. They have worked out a procedure for covering most of the regions of essential interest using 2 runs of the CMM at 15-mm steps that speeds the mapping process without sacrificing detail or precision. Each run requires about 9 hours. They are planning to make 2 CMM runs over this weekend after the 4th rubbing run is completed. The goal is to flatten the arc structures seen in the original full-aperture map, and to continue this until they reach the limit of the CMM precision (~1-micron). From there they will flash polish the piece and take the first optical interferometer tests of the surface.

So far they are on-schedule. Ross is continuing to work with SOML on this, and we will plan on a videoconference once the next milestone, the first optical testing, is completed to review progress.

MODS Software

Ray has nearly completed the IIF/TCS modules, and is preparing a report for tomorrow's LBT Software videocon. So far, everything is working well with the new IIF from LBTO, expecially the block reads of TCS parameters. Ray has worked out a way to setup the content of the block reads using external files so we can customize the process without having to break into the code.

In other work, Ray rediscovered some old VLBA code of his that will work well for traversing and displaying runtime logs. He will be incorporating that into the ICS system in progress.

In lab work on the focal-plane suite, Ray ran the multislit and AGW mechanisms together with the filter wheel using the 4-axis box, and has worked out some of the multiplexing issues with the initial software suite. He is now ready for the 16-axis IE box. Other work included finishing the dark-slide testing, and polishing off some widgets developed from that work.