From vsd@astro1.shef.ac.uk. Thu May 31 14:46:28 2001 Date: Thu, 31 May 2001 14:02:19 +0100 (BST) From: Vikram Dhillon To: Andrew Vick Subject: Re: Design review results doc. Hi Andy, Here is my contribution to the documentation you requested. Sorry it is a little late. Regards, Vik. Optics procurement, coating and mounting ---------------------------------------- > Current status Lenses: Under manufacture by Specac. Windows: Under manufacture by Specac. Filters: Quotes received from Asahi and Barr. Asahi selected. Dichroics: Quotes received from CVI, Stilint and Barr. CVI selected. > Major milestones Lenses: Delivery of coated lenses, mounted in barrels, expected at end of September 2001. Windows: Delivery of coated windows expected at end of September 2001. Filters: Order to be placed in mid-June. Delivery expected by mid-August 2001. Dichroics: Order to be placed in mid-June 2001. Delivery expected by end of August 2001. > Raised issues Lenses: Colin Dickson: "The Calcium Flouride optics ( approx 108.5 dia. x 15 thick ) need special consideration during instrument build, handling and operation, to protect them from physical damage, stress points ( already identified), and thermal shock. Resolution: Specac have been contacted about this. It has been made clear that the lenses will have to operate in temperatures ranging from 263 K to 303 K and accommodate temperature changes of up to 10 K/hour. Specac have already taken this into accout in their barrel design, but have suggested they test it via thermal cycling (which we will have to pay for - awaiting a quote). The barrels themselves will protect the CaF2 elements from physical damage during instrument build, handling and operation. Windows: No problems foreseen. Filters: Are they affordable within the current budget, given that the ING have pulled out of the buying consortium? Resolution: Yes. See overall project management section below. Dichroics: 1. Will they produce ghosts? 2. What if the incident light is polarised? 3. In what way are the images in the three arms rotated/flipped/mirrored? Resolution: 1. The dichroics will not produce detectable ghosts, thanks to the fact that they are in a collimated beam (i.e. the ghosts will fall on top of the direct images). 2. If the incident light exhibits variable polarisation, the dichroic cut-points and overall efficiencies will vary. The only way out of this is to either depolarise the light using a rotating half-wave plate (available in the WHT A&G box) or not observe such objects. 3. A key requirement is that the images in each arm fall on the same pixels on the CCD. It appears that the images in the blue and green arms are 180 degree rotations of each other, so the chips can be mounted in such a way to counteract this. The red arm, however, is a mirror image of the other two. DA/DJI believe this can be resolved in the electronics, but this needs to be checked. Tully also agreed to check that the images are indeed rotated/mirrored in the way described above using Zemax. > Risk areas None foreseen. Overall project management and commissioning -------------------------------------------- > Current status Project currently on schedule (and on budget) for a successful commissioning run on the WHT in February 2002. > Major milestones May 2001: CDR. Sept 2001: Construction of opto-mechanical chassis complete. Sept 2001: Delivery of the complete camera and collimator optical assemblies (and filters, windows and dichroics). Sept 30, 2001: PATT and commissioning time deadlines for Semester 2002A. Oct 2001: delivery of detector and data acquisition systems from UKATC. Oct 2001: delivery of pipeline data reduction system from Southampton. Dec 2001: Completion of integration, alignment and testing at Sheffield. Jan 2002: Packing and shipping to La Palma. Feb 2002: Commissioning and first science observations at the Cassegrain focus of the WHT. > Raised issues 1. Additional visit to UKATC by MJS+VSD required to review the final mechanical design in greater detail. 2. Some of Tully Peacocke's time will be required at the end of 2001 during the alignment stage of integration (either at Sheffield or the UKATC). 3. An acceptance test document will have to be written and agreed upon by the time UKATC deliver their system. This will largely be based upon the contract signed by UKATC and the University of Sheffield. 4. The project will most probably be just within budget, assuming that the problem with claiming VAT from PPARC for the UKATC work is resolved. VSD agreed to contact PPARC about this. 5. There is currently just over 19 kpounds left in the ULTRACAM budget, which is not quite enough to pay for the remaining optics, mechanical parts, data reduction PC, disk space, tape drive, tapes, integration and commissioning costs. A large fraction of this, however, is for the tape drive and tapes. If we are prepared to forego archiving our raw data, we will be just within budget. It was agreed that archiving raw data on tapes is unecessary, given our limited budget, the presence of the pipeline reduction software and the huge (potential) capacity of the RAID array. It was agreed that we would instead spend as much money as the budget allows on hard disks for the RAID array. 6. An approximate quote for the Aristarchos collimator has just been received from Specac (6 kpounds). This will have to come from the British Council grant recently awarded to Emilios Harlaftis and VSD. It is not clear, however, that we will be allowed to spend the BC money on the collimator. If not, there will be a serious budget shortfall. > Risk areas 1. Reclamation of VAT from PPARC. 2. Use of British Council grant to purchase Aristarchos collimator. 3. The decision not to archive raw data means that the pipeline data reduction system must be able to fully reduce the data in real-time or near real-time. This has yet to be fully tested.