Description of activities in this Quarterly Report is abbreviated in lieu of the much more complete account in the CDR Report, which was presented on November 17, 1995. Some of the activities described here continued beyond the quarter to November 1. Budget and Schedule are reviewed as usual.
2. Mechanical:
1. An error budget was prepared for image quality and image stability. Image quality is acceptable, but the goal for image stability (0.25px) cannot be met passively and will require active flexure compensation.
2. A finite-element analysis of the 2-inch thick steel drive disk was carried out. Passive deflections are acceptable.
3. Construction is 80% complete on the collimator cell.
4. Construction on the tent mirror cell is 60% complete.
5. Further progress was made on the grating slide mechanism, grating mount, and census of which gratings will go in each position. A barebones grating-change procedure and handler/helper was developed.
6. Filter size was selected, ant the filter wheel was laid out.
7. Dave Cowley visited CARA to discuss a rail/installation/storage schemes for the Nasmyth platform. A scheme was adopted involving a turntable arrangement that will be shared with NIRSPEC. CARA has generously agreed to fabricate it. We are now designing the hard points to support the instruments when in use.
3. Optics:
1. Harland Epps is currently not working with the DEIMOS Project owing to disagreements over his tasks and areas of responsibility. Negotiations are continuing.
2. Lens couplant material: Last quarter, an experiment to couple two CaF2 and a flint element with Sylgard 527 failed. This quarter we carried out several tests of grease on the same setup. The grease layer did not fail internally like Sylgard, but it did migrate substantially and non-repeatability with temperature cycling (25 C to -15 C). It was therefore deemed unsuitable. Rigid cements appear to induce undesirably high internal stresses. (Dan Fabricant, private communication.) We have therefore adopted fluid coupling as the preferred coupling solution for most of the camera elements.
3. Finite element analysis of gravitational deflections of several optical elements were carried out, and the effects on image motion and image quality were incorporated into anerror budget. Gravitational deflections of the collimator have only a small effect. The tent mirror is swaybacked at a level that is just objectionable (0.03" of image motion), and we may want to correct this with some kind of simple actuator. Distortions of camera lens elements are small, except for Element 6, which is thin and affected by hydrostatic pressure. We may want to couple this element with cement or grease.
4. Brian Sutin computed sensitivities of the image quality and stability to displacements and tilts of the camera lenses. The predicted effects due to deflections in the planned elastomeric lens support scheme (see next item) are generally small except perhaps for Element 6.
5. In light of points 2-4 above an athermalized, elastomeric scheme to support the camera lens elements is the current preferred option. Elastomeric beads around each element simultaneously support the glass and contain the coupling fluid. By controlling bead width and thickness, the design can be athermalized using outer support rings made of aluminum. With RTV560 as the elastromer, lens deflections are estimated to be on the order of 0.001-inch and the mismatch among those deflections is on the order of 0.0003-inch. We are indebted to Dan Fabricant and Bob Fata for suggesting the elastomeric approach.
6. Conversations with LLNL and Cleveland Crystal to Solgel coat the camera optics have begun. Dip tests will be conducted to verify that the Solgel solution is benign on our glasses. However, Cleveland Crystal does not anticipate a problem.
7. Glass production and CaF2 production at Ohara and Optovac are on schedule. Glass delivery is expected in early December.
8. A barebones alignment plan for shop assembly in Santa Cruz was developed. A plan for integration to the telescope is still needed.
9. The design of the optical tooling needed for the camera lenses is well along.
4. Detectors:
1. A problem has developed with the CCD devices from Orbit. It stems from an undiagnosed failure or impurity in the silicon wafers supplied by a subcontractor. Orbit is checking, but progress has been slow.
2. Thinning activities were delayed owing to schedule slips at Davis. These have been resolved, and work is expected to pick up again soon.
3. A Lincoln Labs 1000K x 1000K thick device is due here for testing. The amplifier characteristics should be typical of what we can expect on the real devices. Work on our contract is proceeding, and a preliminary chip layout was circulated and approved.
5. Software and Electronics
1. Bob Kibrick conducted a thorough inventory of all motors, actuators, switches, and sensors. The electronics schematics are being updated to reflect these findings.
2. We are lacking an adequate number of digital I/O bits. Solutions are being explored.
3. Two handpaddles are being designed to allow manual control of all stages without the need for the instrument computer.
4. A first walk-through was held of routine maintenance procedures, including grating changes. The results of 1 and 3 were reconciled to these findings. In normal practice, these procedures will be managed by the instrument computer, which will guide that Astronomer and/or Instrument Specialist through a set process. A start was made on software requirements for these.
5. Further progress was made on the layout for the GUI.
6. The Software PDR is still planned for late February.
6. Budget:
The budget and expenditures through the end of September 1995 are shown on Table 1. To the end of this quarter we spent a total of $873,392 on the project, $348,263 of which was on labor and $533,100 on materials and supplies.
At the end of this quarter, the budget was revised to reflect the current project expectations. Table 2 shows the revisions, which resulted in a net increase to the contingency fund of about $60,000. The major contributor was the decrease in the estimated cost of the mask cutter due to the fact that we can cut very acceptable slits with a modified NC machine rather than a laser cutter.
During the quarter we spent $164,497. Of that amount approximately $58,000 was for materials and supplies. The major expenditures for materials and supplies were $16,000 for flexure control piezo drivers, and $12,000 for optical fabrication materials. We also spent $15,000 on mechanical items used to build the collimator cell, prototype the slit mask handler, test mask cutters, and generally on the structure. Significant labor effort was also expended in Optics and Mechanics during the quarter. In Optics, optical couplants were being researched and optical fabrication tools for the camera designed. In Mechanics, we continued with the design effort, built the collimator cell, and prototypes the slitmask handler and the tent mirror support.
In terms of overall labor contribution, we continue to be below the original projection (see Figure 1), primarily due to the fact that optical fabrication of the cameras has not begun nor has a major software effort. Optical fabrication of the collimator is scheduled to start in the 6th quarter (and has), and the Software Group is preparing for the Software PDR, currently scheduled for February 1996.
Expenditures on materials and supplies is about as expected (Figure 2). Overall expenditures on the project are a little lower than the original projection (Figure 3).
7. Schedule:
Figure 4 shows the current project schedule. With the possible exception of the software effort, we remain on schedule for a projected commissioning date in mid 1998 for the two beam instrument.
The following is a list of the milestones for the quarter from Quarterly Report Four, together with the progress made on them:
1. Preparation for the CDR started during the quarter, including work on the report, schedules and logistics. (The review was held as planned on November 17 - 18.)
2. Work continued on the grating slide, slit mask handling assemblies, collimator cell, tent mirror assembly and the camera cells. A prototype slit mask handler was constructed which proved the concept. Very good progress has been made on the collimator cell construction, and a prototype of the tent mirror assembly was completed. Little work was done on the grating slide during this quarter to allow progress on the slit mask handler.
3. As stated above prototypes for the slit mask handler and tent mirror assemblies have been completed.
4. Construction of the collimator cell is in progress and will be completed next quarter.
5. No work on the CCD mosaics was done in this quarter, and is not expected to start until the early part of next year. This slippage is not expected to effect the progress of CCD or dewar development.
6. Research on optical couplant continued through this quarter, with use of grease showing moderate success and the probability of using a fluid increasing.
7. Cold tests on the motors, motor drivers, and encoders were successfully completed.
8. Testing the Lantronix terminal server continued and were successful. Use of this device has now been accepted into the project design.
9. The list of DEIMOS FITS keywords for CCD mosaic images was circulated at the September SSC meeting. No objections were noted.
10. A detailed list of all proposed DEIMOS keywords has been started.
11. Preparation of the functional requirements documents has begun.
12. Testing of the Orbit chips began, with disappointing results.
Milestones For The Next Quarter:
1. Complete preparations for, and hold the optical/mechanical/electrical CDR (it was held November 17-18, 1995).
2. Continue with slit mask holder design, and improvements of the prototype.
3. Pick up the design of the structure, rotator and instrument handling facilities on the platform.
4. Work on the mechanical design of the camera cells to accommodate grease and alternately oil as the optical couplant.
5. Continue development of the error budget.
6. Continue research on optical couplants.
7. Receive the Optical Glass and start recalculations based on the melt sheet data.
8. Complete the collimator blank and start optical figuring.
9. Complete the collimator cell and install in model.
10. Continue with a detailed list of all proposed DEIMOS keywords.
11. Continue preparation of the functional requirements documents and prepare for the Software PDR.
12. Continue with the CCD development efforts.
13. Decide which option, either delivering one or two beams with the instrument, is the base schedule. Currently shown as the two beam option.