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

MODS Optics

Paul Byard reported on the state of the MODS small optics that were polished by SOML and then delivered to JML for coating. JML reported that the blue field flatteners were very rough: 120/80 scratch/dig instead of the 40/20 scratch/dig specification for the parts. The field flatteners have are being returned to OSU for inspection and may need repolishing. JML will be attempting to coat the red field flatteners to see if they will be usable.

As a preparatory fall-back, we have asked JML to give us a quote on making new small optics from scratch (2 field lenses, 2 red field flatteners, and 2 blue field flatteners) to replace the unacceptable parts made by SOML. The red field flatteners are made of expensive NZK7 glass that has long order lead times, so we will also explore what can be done to salvage those parts. We hope they are OK.

MODS Assembly

Tom reported on the design of a mechanical laser alignment tool for MODS that can launch a HeNe laser beam either direction from the instrument focal plane. The laser fixture uses a pentaprism to align the beam perpendicular to any given subassembly mounting point to verify proper alignment, and can shift the x,y position for fine alignment. The alignment system will dock in the multislit mechanism (in place of a slit mask).

MODS has been assigned space in a large indoor loading-dock building on west campus across from the Electrosciences Laboratory. The space is one of 3 high-bay loading docks designed to accommodate tractor-trailers, and has a 14x20-foot door. MODS2 will occupy one of the loading bays starting in mid-August, about when we can take delivery for MODS. The space has concrete floors, power, heat (but no A/C), OK lighting (we'll need to rig better work lights), and is very reasonably priced (~$10K for the 2 years we'll occupy it).

MODS Mechanisms

Tom has been working with the MicroLYNX motors and their Windows software to operate the slit mask system in the lab. This is giving us a lot of experience with the MicroLYNX motors, and they are proving to be close to ideal for MODS. Things are going quite well on this front.

Mark has finished the load analysis of the dichroic beam selector, he's writing up a test report, and generating the RFQ for the machined parts. With this done, he has started working with Bruce on the design of the MODS CCD dewars.

MODS Schedule

The analysis of the revised MODS schedule is complete, now including the latest formal estimates from SOML on their delayed delivery of the MODS large optics. We are now looking at these deployment dates for the two instruments: MODS1 in late-November 2006 and MODS2 in mid-November 2007. These are our current working targets, subject to revision as always. These estimates also do not include readiness of the LBT to receive and mount MODS, so we expect the deployment target to slip further, with us easing our work schedule accordingly if a later practical delivery window is indicated.

The next MODS meeting will be on Tuesday May 24 (travel and the LBT board meeting in Columbus pre-empts our regular times).