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

Attendees: Darren DePoy, Dan Papallardo, Jerry Mason, Tom O'Brien, Paul Byard, Jen Marshall, Pat Osmer, Mark Derwent, Amy Stutz, and Rick Pogge.

Optics Fabrication

Darren visited SOML earlier this week and got an update on their progress with the MODS camera optics fabrication.

To recall, SOML is the prime contractor for MODS optics, making 4 camera primaries, 4 camera correctors, 4 field flatteners (dewar windows), and 4 field lenses.

SOML is making excellent progress. They have two full-time opticians working on it, and are going to subcontract to a third part-time optician.

All substrates are in hand except for the two red field flatteners, as we have not yet decided to go with BK7 or NZK7. They need to know within the next 3-4 months, so it is not a problem.

All of the materials for making their tools are on hand, in particular they have the 6 large granite substrates, a diamond tool for their NC mill, and have installed their new coordinate measuring machine (CMM). The manufacture of the tools is well underway, with 3 of the granite pieces already having spherical surfaces generated, a lapping fixture for the camera primary mirrors made, a holding fixture for the blanks, and molds for casting various tools out of E6. Also encouraging are that the null lenses for testing the correctors are nearly complete.

With all of this in place they will begin grinding in the next few wkees, and hope to have the initial spheres on the corrector lenses and camera primary mirrors by the start of 2003. At this pace, we could see the first optics for the MODS1 blue channel by mid-2003.

Mechanical

A package of drawings has been sent to ASU for making the camera primary focussing mechanism.

The last big remaining design issue is the MODS focal plane. In particular, there was much discussion about the Acquisition and Guide cameras, and what their specifications are. Darren has been tasked with developing a specification document. Our first-order plan is to adopt as much of the current Potsdam AGW system as we can to MODS, meaning primarily cameras and their related software.

As a reminder, MODS extends too far into the Gregorian focus station to use a straight-up AGW unit as is being designed for LUCIFER. Instead, we will adapt key components (namely the guide camera and shack-hartman sensor) to the MODS focal plane area, providing the various mountings and mechanisms ourselves.

The other remaining issue is the Calibration System. Rick has been tasked with revising the previous draft calibration protocol document into a specification document for the new system as it has emerged. This will provide Tom with what he needs to work with Paul to determine the final design and placement of the system relative to the MODS structure.