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

Attendees: Tom O'Brien, Ross Zhelem, Dan Pappalardo, Jason Eastman, Ray Gonzalez, & Rick Pogge

Optics

Ross reported on the results of the first rubbing trial on the red corrector lens at SOML. Steve Miller made a single densely-sampled CMM run with 15-mm steps covering the test region. A single run means no stitching is required. The data look very good, <1um p-v typical residuals in smooth areas, consistent with the expected precision of the CMM. They have achieved the desired 2um/run removal rate on the test region, and are setting up for first a full-aperture 15mm step run with the CMM to make a final high-res surface map, and then start on removal of the the high spots. Ross will receive and analyze the raw CMM data and help create the final hit map

SOML also reports that their optical testing setup is in place and running well, so they will be ready once the rough figuring is done to polish the parent and do full-aperture interferometric tests. They have measured the key wavefront errors of the test setup and return sphere, and have the system full characterized and ready to go.

Ross has a quote for the calibration system integrating sphere port window. It will be a 100mm diameter, 6mm thick piece of fused silica polished flat with no AR coating. One thought is have a hole drilled in the part to use as a way to mount the secondary obscuration mask. Ross will iterate with the vendor on this question - it should be possible.

On the to-do list is to work with Dan to locate all of the lamps and mounting parts for the pen-ray wavelength calibration lamps and quartz-halogen continuum lamps. They should be located among Paul Byard's cabinet of parts in the small downstairs lab where we keep all of the other optics.

MODS Electronics

Dan reports that the Rev2 board is out for manufacturing and the finished boards should arrive in a week. Also, all of the components to populate these boards have arrived, so he will be ready to start assembling the motor boards once the PCBs arrive.

Dan is finishing up the final drawings and pin-out tables for the Calibration/AGW stage hardware interlock cable. We have a concensus for the packaging of the interlock hardware, and Jerry Mason has ordered 2 sets of hardware for this. We should have a working prototype in the next week or so.

MODS Software

Ray has been working with the MODS dark-slide mechanism in the downstairs shop where it has been mounted on MODS1. He ran it with flight wiring and a lab 4-axis box for 1000 cycles. His tests led him to modify the data sheet for the dark slide to slow down the speed by 50%, as it seemed a little too fast. At the new speed it closes in 2 seconds, which is plenty fast enough. The earlier higher speed had some minor bounce issues, and looked more dangerous than it really was.