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

Attendees: Darren DePoy, Jen Marshall, Tom O'Brien, Jerry Mason, Bruce Atwood, Paul Martini, Paul Byard, Ray Gonzalez, Pat Osmer, Mark Derwent, Dan Papallardo, & Rick Pogge.

MODS2 Structure

Tom and Mark visited Indian Creek Fabricators last week for the last fitting of the MODS2 structure. Indian Creek is a lot busier place than when we first started working with them. Tom & Mark setup for the alignment test of the collimator structure with the upper structure, the last set of measurements (using a 5-meter measuring rod) required before the final welding and collimator arm attachment can proceed. The process, once going, is very deterministic, and was "extremely successful": all measurements were within 1-2mm over roughly 3.5meter distances. The system was left in Indian Creek's hands for finishing, and should be done and delivered by the end of October. We may also take delivery of the original assembly fixture for the upper structure for storage on west campus.

The "Birdhouse" on west campus where we will store and work on MODS2 while MODS1 is in the main McPherson shop is taking shape. We've taken delivery of the 3-ton crane and will proceed to assemble it. Everything will be ready well in advance of the MODS2 delivery.

IMCS Testing

Work continues to prepare for the full-up Image-Motion Compensation System (IMCS) tests on the MODS1 structure with the blue-channel optics. Highlights:

• The multislit mechanism is now mounted in its final configuration. This went better than anticipated: only one custom cast-epoxy shim was required, all others used fixed-thickness shims. The multislit mechanism defines the fundamental frame of reference of the MODS optical system, so this is a crucial milestone.
• With the multislit mechanism in place, the alignment with the docking ring was confirmed, then the collimator "foot" structure was tested. It is where it is supposed to be, within 2mm in over 3.5-meters of path-length.
• Jason has nearly finished installation of the dichroic beam splitters in the laser projectors. Still a few finishing details to complete.
• Dan and Ed have finished wiring up the collimator tip/tilt/focus (TTF) actuators, are beginning testing. The first 3 TTF actuators that pass the test will be given to Tom to mount on MODS1 for the IMCS tests, with the other 3 going to Ray for testing the motion-control software.
• The collimator mirror for the tests has been mounted and silvered and is ready to install on the TTF actuators.
• Mark has populated one of the grating-select turrets with two flats: one in a grating-tilt mechanism that will only be used for gratings in the deployed MODS, and the other in the standard "manual" adjustment system that will only be used for flats in a deployed MODs. Both have bypass gratings installed in the center holes. The was mounted in MODS1 today without incident (it takes a couple of hours).

  One of the remaining issues with the imaging flats is to test the flat/grating co-alignment procedures. This aligns the flat or grating along the slit axis by using a double eccentric mechanism on the tilt-axis bearing. This will be cumbersome but only needs to be done once.

• The silvered camera primary mirror is mounted in its cell, and ready for integration into a camera. The camera truss rods need to be painted (there are some mild spots of corrosion on the invar rods, all about the size of finger prints), and then the blue camera (less corrector lens) will be re-assembled.
• The Quad Cell Sensor mount is being assembled and should be in Tom's hands for mounting in the completed blue test camera soon.
• Dan is assembling the 4-axis motion control electronics box (the so-called "4-side box") needed for the IMCS testing.
• Last week MODS1 was successfully rotated in position angle by "indexing" it on the mounting ring by 60-degrees (MODS mates to the mounting ring using 6 ball-and-socket points at 60-degree intervals). The procedure turned out to be very easy when good tail support is provided.
• Ray has be iterating with Tom and Mark on the software needed for the IMCS tests. This software includes modules that will be part of the final IMCS control system, and a series of test utilities that will be needed by Tom and company for lab testing and integration, with the end goal of becoming part of the eventual engineering support toolkit for the delivered MODS.

MODS Slit Masks

Tom has taken delivery of test pieces of MODS mask blanks with various coatings, purchased from NiCoForm, Inc., an electroforming company in Rochester, NY. The masks are made of NiColoy&tm;, NiCoForm's proprietary Nickel-Cobalt alloy, electroformed to a thickness of 150-micron in the correct spherical shape for MODS using a spherical mandrel. The vendor has modified the tooling to make removal of the finished piece easier. In addition to uncoated NiCo mask blanks, they produced blanks coated on both sides with Copper Black (and it is real black, if a wee fragile), and with Gold on the convex side and Copper Black on the concave side (a test concept for LUCIFER masks). So far they look terrific, and while the thickness uniformity could get better, this is a normal improvement path when starting an electroforming process. NiCo is about the best material to use for laser machining, and has lots of promise as a mask material for MODS.

With the mask blank samples in hand, the next step is to do test laser machining to see if they will produce slits good enough to meet our specifications, and what laser parameters are required (laser power, beam delivery optics, etc.) This latter will let us make a more informed decision about what laser cutting head will be required.

We've begun discussions with a possible laser machine vendor about a promising path to getting a suitable laser machine. One option we are considering is mating a laser cutting head (diode-pumped Nd:YAG) with a mini-Haas 3-axis milling machine. It has lots of desirable properties. The vendor is an integrator that works with a German laser firm. This vendor has also expressed interest in doing test machining of our parts using a similar machine.

CCD Dewars

We have placed an order with Meyer Tool Company for 5 dewars. We expect delivery of all 5 within 18-weeks of their receiving the order, hence likely in late-Feb/mid-March 2006.

Bruce has recieved a response from Mike Lesser regarding the CCD design effort for MODS. We are waiting for the response from E2V (due Oct 12 or so), and will then be deciding how to proceed. We want this to start as soon as possible to ensure we have the best detectors in time for MODS2 (we will retrofit MODS1 at the same time MODS2 is deployed: MODS1 will be initially deployed with 4Kx4K CCDS provided by the UA ITL).

New ISL Positions

The ad for the new Electronic Technician (Jr. Engineer) level has appeared in the most recent campus "Green Sheet", and will be posted to local papers soon.

Once the Optical Engineer ad appears officially, we'll be posting to the AAS Job Registry, CCD-World, SPIE, etc.

MODS Electronics

Dan reports that all the machining is done for the metal parts of the "4-Wide Box" (4-axis motion control electronics), and he will start assembly soon.

In the meantime, Dan has been busy testing the Collimator TTF actuators, and calibrating the proximity switches and connectors. Ed has wired up three 6-meter cables needed for the IMCS, but we'll just wire the motors in directly at this point as we do not yet have a final motor cabling design ready (the IMCS test exercise will help inform how to best address that). So far tests are proceeding using the 1-axis motion control system (the "Single-Wide Box").

MODS Software

Ray has the IMCS analysis software about done. All of the components have been integrated into the Instrument Manager and are working well. The current work is building a GUI for Tom that provides a real-time x,y plot of the quad-cell output for IMCS testing. So far it works very well. We can readout the Quad Cell at about 100Hz max, and get realtime plots plus logging for later analysis (e.g., to do analyze vibration modes, etc.). This tool looks like a promising prototype for a similar toolkit for monitoring motors in real-time. Ray and Tom are working out the detailed specifications.

MODS Mechanicals

Mark reports that he has received all of the parts for the Dichroic Beam Selector drum, and assembled the first unit. It looks great, and no major re-work is required. This is the last major mechanism for MODS, so we're nearing an important milestone on the moving parts of MODS.

The next big looming job is the MODS enclosure. This design affects so many areas of MODS (light tightness, service ports, where to mount electronics, dewar fill ports, etc.), that we need to get onto this and discuss it further over the next few weeks.

SPIE Meeting

The next SPIE Astronomical Instrumentation Meeting will be in May 2006 in Orlando, Florida. The abstract deadline is in November, so talk to Darren if you are planning to attend and/or give a paper/poster.

Upcoming Events

For next week, the main topics will be the on-going large-optics fabrication saga, optical coatings, the enclosure design, and an update on the budget.

The new LBT Director Richard Green and Mark Wagner will be visiting OSU on November 1 and 2.