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

Attendees: Andy Gould, Jason Eastman, Jerry Mason, Ray Gonzalez, Tom O'Brien, Dan Pappalardo, Ross Zhelem, Bruce Atwood, Paul Martini, & Rick Pogge.

MODS Enclosure

All of the parts for the framework for the MODS1 enclosure have arrived from item and assembly has begun in the shop downstairs. We can expect to see the completed framework by the end of July.

MODS Optics

Ross had no news from SOML on red corrector lens progress but was planning to have a talk with Steve Miller later in the week and he would update us next week.

Other optics progress briefs:

• The optical flats for the calibration system integrating sphere exit ports have been ordered and we can expect them in a few weeks.
• The Blue Camera Corrector Lenses have been packed and are awaiting the paperwork before they can be shipped to ZC&R for optical coating.
• The calibration system projector lenses are ready to mount in their cells, with protective covers fabricated and ready to go.
• Ross has most of a draft of the proposed optical alignment procedures that he will be circulating shortly.

MODS Electronics

Dan completed his power budget analysis for the lamp control box, now including the IMCS IR laser unit. The IMCS laser dissipates 5W at 50% duty cycle. All the other systems combined add only 2.5W, so this looks very good for passive cooling, reducing the amount of extra glycol plumbing required on the instrument.

The current lamp box conceptual design includes a WAGO node and 24V power supply, which looks to be a very good solution for controlling the lamps. It becomes a separate network node and is separate from the IEBs, so we don't have to worry about properly swapping and rewiring the lamp controls if we have to swap out an IEB on the mountain. Dan is now proceeding to the detailed design and purchasing of the test parts.

The only sticky bit is that the ThorLabs IR laser we are using for the IMCS is only rated for operation at ambient temperatures between 15-35C. We are talking with technical service people at ThorLabs to better understand how this spec was set, and in the meantime Dan is setting for a cold-soak test to run the laser at -20C in the freezer.

MODS Software

Ray reports that he has been running 9 mechanisms simultanously with the 16-axis IEB#1 in the lab without problems. The software is fine, and he is proceeding to various failure tests, as well as tests involving defeating the hardware interlock for the AGW Stage and Calibration Tower to thoroughly test the backup software interlock. To continue with the multi-mechanism tests, Ray needs to get telemetry on the drive power supply voltage and current through the WAGO units. Dan has been tasked with setting this up.

PLC coding for the MicroLynx controllers is going well, but some issues have emerged between the initial lab checkout coding done by the engineers and the "production" coding for the final control system. The final production coding is more like a state machine, whereas the test coding tends to be more interactive, and uses subroutines in ways that don't work well in a state-machine architecture.

MODS CCDs

Bruce reports that Phil has been making excellent progress on the Altera communications issues, with help from technical experts at Altera (he finally got through to the right engineer). The USB interface is now working very well. They are getting very close to running an actual system to prototype the MkIX digital interface and clock bias boards.

After the meeting, we are invited to look at the mechanical sample 3x8K CCD in Bruce's lab.