DEIMOS Meeting Minutes Thursday, March 23, 1995 NS-143 9:30 am Present: Terry Ricketts, Marlene Couture, Eric James, Jack Osborne, David Hilyard, Richard Stover, Dean Tucker, David Cowley, Steve Allen, Sandy Faber, Bob Kibrick, Harland Epps, Neal Jern, Deanne Lago. Announcements · The optical glass was ordered (3 barrels + 2 additional spares for the first element) for $193K (we had budgeted $80K) so the following items were removed from the budget: · The window, we will still design the cell and if a window is available later, it could go right in. · Optical Equipment 20K - this amount listed was for equipment that had already been purchased. · The Supplies Budget was reduced by 12K, which was largely the lab renovations. · The second TV camera. If anyone wants a detail of these changes David can mail you one. Approximately 103K was identified with these savings, 90K went into the Optical Glass budget and the remainder put back into the contingency. · Bill Shepard has left Lick, David will now be doing the work on the Laser Cutter until another individual can be identified to take on this task. Terry Ricketts is working 1/2 time until mid-June on the Electronics Budget and other items Bill was working on. · The meeting with Frank Melsheimer last week went really well, notes were circulated, if you want a copy please notify Deanne. · A prospectus is being prepared for the second beam, which will require its budget projection. David will be passing out the draft for input/corrections before a final version is done. Detectors A handout was distributed regarding the CCD thinning effort being done here at Lick. We are using the UC Davis micro-machine facility right now. Bill Brown is devoting at least two days a week at Davis using their facilities, where we can do all the chemical thinning steps while we are putting our facility (including a class-100 cleanroom) together. We will also be able to use the UC Davis facility during the seismic upgrade work which will be done on Nat. Sci. II (while the building is vacated). The lab will be more elaborate than our first design because we have obtained over 130K of equipment donated by Intel, this was exactly the equipment that we needed and more. (A complete wet bench and several other pieces of equipment designed specifically for thinning wafers.) The cleanroom is being financed by CARA. When Nat. Sci. II is vacated the Natural Sciences Division will provide funds to relocate our thinning efforts back to Davis during the construction work. It is anticipated that we will only have to vacate our facility for approximately two months. We have been making modifications at Orbit to the original CCD design to make various parts of the thinning operation easier to do and to improve the yield that we receive from these devices at Orbit. The first run is underway at this time, results should be received in approximately six weeks. Richard brought a sample of one of the first test wafers to the meeting which has been bonded and thinned (without CCDs). They consist of a silicon wafer (just like the ones that we make the CCDs on) bonded to a handle wafer and then thinned. We are doing thinning experiments/tests to characterize the process. The way these devices are thinned is to glue them to the handle wafer, then the CCD wafer is mechanically ground down to a couple of mils and then chemically thinned. This chemical process is designed to stop at our epitaxial layer where the active part of the CCD is. The thermal characteristics of the handle wafer and what is being bonded to it is identical but the glue has it's own properties. It will be a thin layer and we don't anticipate a problem with it at this time. Our milestones have changed slightly: · The packaging goal (originally three months), will be deferred for awhile because proper development of the packaging depends on the design of the CCD itself. · The chemical thinning total was seven months to thin silicon (without CCD), and we're on schedule now. We're hoping within the next month or so to have a CCD uniformly thinned to the correct thickness. · The wafer slicing original goal was nine months to slice them to where they are actually buttable. This work has not been started. We have encountered one small problem, the CCDs can't be seen through an IR microscope to align them on the wafer saw because of the aluminum nitrite coating which is opaque to IR. We're hoping that with a sufficiently bright IR source we will in fact see the wafer. If we can't we will have to investigate the slicing process further. · The finished CCD in twelve months can still be obtained as everything stands to date. Lincoln Labs has been fully approved by the Air Force. The Keck/CCD working group met to go over the contract with them and have made a few modifications to it. (Jerry Luppino is in charge of this project.) Their devices are looking pretty good especially because they will have lower read noise than the Orbit devices. However the Lincoln devices may not be ready in time for DEIMOS needs. It should be noted that the Lincoln devices do not have an MPP mode. Harland must be assured that the CCDs are flat because he can not make any optical adjustments for them if they are not flat. Richard stressed that they are checking flatness during each step of the thinning process. Structure Eric James will begin full time on the DEIMOS structure immediately. After our meeting with Frank Melsheimer it was decided that we were going to go with a monocot structure for the larger part of the instrument because it is so stiff. This structure is a cylinder with bulkheads on the inside for attaching the various things that need to be attached, because we can't attach directly to the skin. The placement of the drive ring and it's width is being designed now. The drive ring can now be larger than 72" in diameter. The 72" number was chosen because it fit on the bullard, however this may have been constraining the whole instrument too greatly. We are not looking at other alternatives, (essentially a larger diameter disk) if it will serve our purpose. If this alternative is chosen, we will have it fabricated elsewhere. In addition to the cylinders, one of the proposals we are looking at is boxing in the camera detector area. This would help to shield the detector/ camera etc. Slit Mask/Handler/Cutter We have talked about packaging the slit mask into a caterpillar instead of a wheel, however we will only be able to move back approximately 3" from the focus. The key question facing us was how to make the slit mask storage thin along the direction of the light travel. The number of gratings have changed from two to three. The slit mask itself has not changed, we have decided upon a cylinder with a tip angle that will make the images best. The tilt is picked once then all the slit masks will be made the same. We are looking at two alternatives for the grating handler: · One is an actual slide in which the gratings are mounted inside a device that moves them to various angles. · The other version would be to mount the gratings into a cell which is in turn moved by a handler and put into a device that places it into the exit pupil plane. Both of these options have good and bad points. We are thinking of independent tilt mechanisms rather than tilt with a whole slide because it needs to move to precise accuracy. The flexure control may have to split into a separate chassis. We may also be looking at putting the servo amps towards the instrument, we really don't want the cables twisting that carry the current for the motors, they will not twist as well as a smaller cable just carrying the signals to tell something else to move. Other instruments have experienced problems with the cable wraps going around the telescope. The servos do not need to be inside the instrument, they can fit on the outside (inside an insulated enclosure). We might want to use the galil servo controllers like MOS which mount out on the rotating part and the only thing that comes off the rotating part are the serial lines. The cutter RFQ will be re-formatted and a draft should be ready within the next three weeks. David will be contacting the vendors to advise them of the changes. The skin material may possibly be 5-mil stainless steel. We will advise the vendors of a stiffness material constant to match and also its opaqueness to our specifications. We are also soliciting the vendor feedback on this as they may think of things we haven't. Cutting speed is also important, we have a minimum specification of eight hours to cut ten masks (this includes the entire process). How repetitive a process is this? Will the whole process fall apart if the operator needs to take a break? Electronics Budget Terry has been looking over the design and budget as it is, to familiarize himself with everything. He has questions about the CCD controller and flexure control system. The calibration lamp requirements still needs to be resolved. What kind are going where? What kind of supplies/ controls are needed? What will the light source be, etalon or a combination of neon/mercury? Terry spoke with Richard, Bob and Wei regarding the CCD controllers. They decided to separate the CCD controllers that will be talking to the CCDs for the flexure correction from the other mosaic controllers. By using the same ones we would be trying to have the same timing card talk to all of them. Bob mentioned that if we are going to use the Lincoln chips we may very well paint ourselves into a corner if we try to use the one controller to run the mosaic and do the flexure control. The Lincoln chip will have to be clocking it during integration in order to keep the dark current down. To try and have the one timing board interlace the clocking of the mosaic and the readout of the flexure chips could be a problem. This will be discussed at another time. However our budget assumes we will be using Richard's chip and should price the controllers on the same assumption. The way the Leach boards are presently designed is that they are made to work with an un-termi- nated VME bus. This is ok if we have a small number of cards with a short bus but with the number of cards we are starting to talk about we will end up with a very long VME bus. This creates the worry about termination. We may be forced to sub-divide this bus into smaller busses and end up with multiple timing cards, each one driving at the most four of the analog boards. Once that is done there is no reason why we shouldn't do the same thing with the flexure corrector. They might go in the same chassis, but they will have to be separate units. A meeting was scheduled for 2:00 pm this afternoon to discuss this. Camera/Camera Optical Design At the SSC meeting in February, our camera design called for a material called BAK-5 and this allowed us to move the camera down to 3900Å. Unfortunately this material is unavailable. We are now implementing our back-up design which utilizes a material called SK-01 as the basic replacement. The downside of this is that SK-01 is more expensive. The upside is that it is available and it gets better transmission. We are now looking at nearly 90% expected internal transmission of the material at 3900Å. We have adopted the pre-construction design, for which we are going to order the glass early in March. Jack has given his mechanical approval to the camera design and Brian Sutin has calcu- lated the end-to-end performance in a worst case limit and it is acceptable. We plan to buy three full sets of the optical glass components from OHARA. We are purchasing three full sets because we want to eventually hope to make two cameras and we must have back- up material. There is no guarantee that because it was purchased once a replacement piece will be available in the future. Each cycle is different so the materials won't be optically the same. Rob Sparrow the General Manager of Optovac who produces the CaF2 visited us on March 7th. A detailed RFQ was sent to him on the 16th and a response is still pending. The delivery delay from Optovac is that they will need to build a new furnace to accommodate our order. We should receive a response from him within a week or two. We own one boule already and are planning on purchasing three additional boules. One of them will be held as a back-up (spare). Optovac will be doing the generating of the boules and send us rough generated lens forms from which we can do the fine grind/polishing. We have the possi- bility that we still have a boule that is not needed it could probably be sold back to Optovac. The timeline for the camera is on schedule as presented to the SSC in February. The only change is that it will now take 6 - 7 months to receive the optical glass (mid October/November). This will create a bit of a problem because the pre-construction design can't be updated and released before all the melt-sheet data is available. This could delay the start-up of the construction, (worst case would be the beginning of January 1996 before polishing can begin.) Brian Sutin has done a study of the collimator and it seems that it will be an elliptical shaped mirror with a elliptical constant of -.75. We need to finalize the mechanical design of the mirror blank and how it is going to be held so we can proceed to order the material. We should be able to grind and polish the mirror as soon as the blank arrives, pending schedule of the flow of work in the Optical shop. Before we order this blank, Jack should sign-off on what it's structure should be like and also a fine-eyed element analysis of the blank by David Hilyard. Some questions pending: · If the blank needs a hole, who cuts the hole us or them? · Who generates the rough curve? · OHARA is also making a Zerodur like material at the moment, but it probably is not much cheaper than Schott. However if we decide to go with zerodur we may ask them for a quote. · ULE has a good price too according to Frank Melsheimer. We are still planning for a solid blank at this time. · Kodak is still being considered for doing the rough generation. · Slumped glass will also be investigated. The PDR committee said we should hold off on everything except for the camera optics until after the CDR therefore we are going to seek approval from the SSC to place an order for the Colli- mator mirror glass. Software We are still planning a software review in early July and to have the documentation for that review frozen and ready for distribution in June. Will we need a separate review later for the controller related software? There are still several issues pending regarding the actual archi- tecture, and the specific characteristics of the Leach-2 system. This will all effect the electronics structure and what the software is going to do. The other option is to try and identify two or three different architectures that might come to pass with the CCDs and electronics. We could give some description of what the software would look like for each of those paths. In the Software PDR we will be focusing on pinning down as many of the requirements as possible. We will want to get some fairly tight functional documents for those areas which we can determine. Unfortu- nately we are still hindered until the CCD development is further along. Personnel wise we are still under staffed. Steve Allen will revert to full-time status starting April 1, 1995 and will be working on the research area identified in the November PDR (i.e. a survey of current disk technology, rating disk drives, through puts, pricing etc.) to obtain some limits on how we can configure a disk for recording the images. Dean is still involved with MOS so can't devote as much time to DEIMOS. Bob has submitted a P.O. for hardware to upgrade Kaminari and it was installed yesterday. This will enable us to begin getting benchmarks of resources required to do basic operations on simulated DEIMOS images. Bob is trying to arrange for a demo of a Quad-rate system (an overlay to the X-windows system) which allows you to take a multi screen workstation and logically make the separate monitors a single physical screen. This will give us a more realistic display of these large images. We unfor- tunately don't have any machines here that can demo it. There is one at CARA and arrangements were made to have a machine available, however the demo version shipped to CARA but it did not arrive in time (before Bob and his group had to leave). Hopefully the folks at CARA can demo it for us, if not we may be able to "rig" something up here. We will need to watch the Epics system which will be used at Keck II. June was identified as a time to review the Epics system at Keck, this may not be in time for our Software PDR documen- tation. This could be a way we want to go with DEIMOS. We need to choose a PDR board and date soon. It should be set for early July to better facilitate the Software group. At the moment the PDR is tentatively scheduled for July 7. Schedule The schedule for the remainder of the project is progressing with a few tight spots. As the CDR will be in November, we are going to start to push to get things solidified for that. Budget The budget is being re-done in the following areas: · Funds have moved funds around for the glass order. · Funding for manpower in the assemble and test areas did not have an actual allocations in them. · The electronics budget is in the process of overhaul. · The money for the second beam is also being anticipated. Late next week David will forward to individuals his proposed changes for review. After input it will be forwarded to Marlene. Change in Scope's will be circulated for particular items. At this time a prospectus is being drafted to present to potential investors. The UCSC Devel- opment Office has provided us with a format, David Koo is writing text, Sandy is locating illustra- tions, David Cowley is trying to prepare the budget. Sandy is hoping to get them the material by the end of next week. The Development Office will in turn take this prospectus to a potential UC investor in Idaho who is thinking about donating funds. DEIMOS will be one of two proposals presented to him to choose from. Quarterly Report #3 The deadline for this report is approaching. David is hoping to have a draft circulated in early April. We need to complete it for our presentation to the SSC in May.