IMACS progress report no. 10 B. Bigelow 2 February 1999 Mechanics Objectives for January: Status: IP A. Complete DS preliminary design (TB) IP B. Complete guider optical layout and start mechanical layout (TB/BS) Done C. Review Schier's camera and collimator proposals (TB) IP/Done D. Complete structure and test/install pallet prelim design (BB) Done E. Review electronics prelim design, start Eng/Tech search(?) (BB) IP F. Review software prelim design (BB) IP G. Start schedule/budget revisions for PDR (BB) Mechanics Objectives for February: A. Complete all disperser server prelim. design (TB) B. Complete prelim. guider mechanical layout (TB) C. Complete MOSS and instrument housing prelim. design (BB) D. Let contract to Alan Schier for optics supports (TB) E. Start PDR meeting arrangements (BB) Optics and CCD reports from Brian Sutin and Greg Burley attached. 1) Project scope, budget, and schedule The PDR committee has been selected, and includes Dan Fabricant (CfA), Jerry Nelson, Steve Vogt, and Matt Radovan (all UCO/Lick). Gerry Luppino will presenting the design of the IMACS dewar and detector array, as well as joining in the remainder of the review. The review is scheduled for Saturday, 3 April 1999, pending final acceptance by the committee members. The review will run from 9 AM to 5 PM. A kick-off meeting was held on 1/26/99, to review the PDR document table of contents, and to assign responsibilities for the various sections of the review. The review will cover mainly the mechanical design of the instrument, but will also include presentations on the optics, electronics, and software. A revised project budget and schedule will also be presented. 2) Mechanics Alan Schier sent us a proposal for doing the work on the collimator, long camera, and field lens. After reviewing his proposal, several refinements were made, and a new proposal has been submitted. This new proposal has been accepted, and Alan is starting work on the contents of that proposal. One of the changes requested was that his (Alan's) work include the shutter mechanism. (Bond) The disperser mechanism has had most of its "sub-mechanisms" conceptualized; however, work is still ongoing. The last of the mechanisms to be conceptualized is the portion that will move the element, cell, and mounting ring from the disperser wheel to the focal plane. (Bond) The instrument drawing tree has been developed. The overall model has been structured in such a way that it will be easy for the mechanical engineers to keep the model up to date, while still keeping their subsections local to their computers. (Bond) Preliminary design of the guider camera stages is behind schedule, but will be completed for the PDR. Sutin investigated the possibility of moving the guider fields to areas outside of the nominal 30 arcmin FOV, and found this is feasible. The optical design of the guiders is ready for the mechanical design phase to start. (Bond) There was good progress on instrument structures in January, but some work still remains. Preliminary designs for the instrument assembly/installation carriage, the slit-area structure, and the camera trusses were all completed. The preliminary design of the main truss is complete. The design of the main optics support structure (MOSS) is in progress, and two models of the MOSS were finished in January. All the structure areas, including the housing, will be completed for the PDR. (Bigelow) In general, we are on schedule to have all the preliminary mechanical design ready for the review on April 3rd. 3) Electronics Dave Carr (Magellan Project) has completed a preliminary description of the electrical/electronic design for IMACS. Dave has provided schematics for all of the IMACS motion stages, a preliminary layout for the electronics racks, and a list of standard Magellan components for use in IMACS (motors, limit switches, stepper drivers, etc). Dave will be providing materials for the PDR, and will hopefully be present to answer questions regarding the electronics. 4) Software Christoph Birk is developing motion control and data-taking software for IMACS and DDI (Magellan IR camera/spectrograph). He will be providing a description for the various software suites for IMACS, as well as an overview of the instrument control system, including hardware (computers) and the network topology, for the PDR. 5) Optics Via Brian Sutin: A significant amount of time was spent on a proposal for another spectrograph for Magellan. 1) The TV system is evolving. New ideas are to leave out an installed S-H calibration system. The S-H system should only require initial calibration, so the calibration lamp and pinhole will be manually installed when alignment is required. The altitude bearing of the telescope does not vignette the field of view until a diameter of 35.65 arcmin, leaving enough room to have the TV guiders partially out of the instrument field of view. The image size at the telescope focus is about 0.05 arcsec RMS diameter at this field diameter, with some refocus. The vignetting from the corrector varies from 6% to 17% of the primary. The extra room amounts to 170 arcsec on the radius, while the TV guider FOV is 105 arcsec. Therefore the guiders can be withdrawn completely from the mask area, at the cost of extra vignetting of the guider. 2) The Dynasil Fused Silica field lens has been shipped to Contraves. 3) Ohara had a bad melt on the FPL51Y, a glass used in the long camera. This will cause a delay of a few months in the delivery of the long camera. 4) A thermal analysis of the collimator and long camera shows that a passive thermal compensation system to correct thermal focus for the long camera is not practical. Therefore the decision was to passively correct thermal scale in both the collimator and long camera. The thermal-focus can be corrected actively with the dewar focus. In the case of an FP etalon, the collimator thermal focus can be corrected with the telescope focus. A simple scheme has been chosen for passive thermal correction in both the collimator and long camera, with Delrin spacers controlling the axial position of a singlet element in each. The thermal analysis of the collimator assumed that the field lens and main collimator body were attached together by aluminum. This will most likely not be that case, so the analysis must be rechecked when a stable design for the structure exists. 5) An initial alignment analysis for the the collimator and long camera showed that the overall alignment tolerance is about +/- 0.003". At this level, a few elements can add about a micron to the RMS image diameter for some image, worst case. Since the current plan is to align the optics during assembly, rather than relying on accurate machining, this number is largely irrelevant. A similar analysis for image motion after assembly gives an overall alignment tolerance of +/- 0.001" in order for the most sensitive elements to contribute about a micron to the RMS image diameter, worst case. This value assumes active flexure compensation. Without compensation, the tolerance is 10 times tighter. Since the individual errors in both of these analyses do not add linearly, taking the RMS average of all of the individual element errors is too simplistic. ------------------------------------------------------------------- TODO, February: 1) Ask coating companies for detailed proposals. 2) Wait some more for delivery of Ohara glass, measure and ship blanks 3) to TORC. Also do melt sheet update. 4) Start thinking about filters. 5) Get cost estimate and drawing for 6.5" etalon from Queensgate. 6) Guiders and CCDs Via Greg Burley: Guider camera progress (Jan 99) =============================== 1 - built and powered up the two header boards (no CCD or TE cooler or temp sensor installed yet) 2 - testing and integration of hardware + software in-progress * DSP writes to digital-to-analog converters * DSP generates clock waveforms * DSP reads from analog-to-digital converters * DSP generates the EEV-specified voltages for clock waveforms 3 - currently assembling a suite of DSP test programs to verify the hardware 4 - updated the guider camera website Mosaic camera progess (Jan 99) ============================== Nothing to report this month.