Smithsonian Astrophysical Observatory, 60 Garden Street, Cambridge, Massachusetts 02138-1516

99 -- FOUR PIECES OF STANDARD GRADE ZERODUR SOL RFQ-BF3024 DUE 032999 POC Point of Contact: Elizabeth Ciampaglia, 617/495-7402, FAX 617/496-7992 or email: eciampaglia@cfa.harvard.edu; Contracting Officer: Peter W. Sozanski, 617/495-7376 The Smithsonian Astrophysical Observatory (SAO) intends to purchase, on a sole source basis, four (4) pieces of standard grade Zerodur from Schott Glass Technologies, Inc for SAO's Hectochelle grating mosaic metering structure. After researching and testing various materials, it was determined that Schott's Zerodur best meets the needs of the Hectochelle design. Zerodur was choosen because we require four pieces of low expansion glass with a coefficient of thermal expansion (CTE) that exactly matches that of the substrate material for the Hectochelle echelle grating elements over the operating temperature range (0 degrees to 70 degrees F). The grating substrates are made of Zerodur, and the only material which matches the CTE of Zerodur with sufficient precision over such a large temperature range is Zerodur itself. SAO has conducted a lengthy design study to find solutions to the difficult problem of fixturing these large grating elements with high thermal stability, i.e., the relative orientation of the two grating elements must be maintained to 0.1 arcsec of each other at all operating temperatures. This precision is obtainable only if the metering structure and grating elements are made of the same material. Zerodur is a ceramic material frequently used in optical applications where high thermal stability and stiffness are required. The weight of all Hectochelle subsystems is a crucial design parameter. As Zerodur has the highest mass-to-stiffness ratio of all low expansion glasses, it is preferred for this application as regards weight. A final issue is the machinability of Zerodur. Since the final metering structure will have numerous, precise details machined into it by a fabricator, Zerodur is the preferable material. The shape of these pieces of Zerodur are rectangular prisms. The dimensions of these prisms are: 1 piece -- 40.25 inches by 12.25 inches by 3.25 inches, 1 piece -- 34.75 inches by 13.00 inches by 2.25 inches and 2 pieces -- 8.25 inches by 5.25 inches by 3.00 inches. Two corners of the largest (40.25 inch long) piece are also to be cut off. These pieces must be furnished with a tolerance of +0.10 inch/-0.00 inch. The surface finish is to be 270 grit or better. All responsible sources may submit a quotation which will be considered. A determination by SAO not to compete this proposed purchase order based upon responses to this notice is solely within the discretion of SAO. Information received will normally be considered solely for the purpose of determining whether to conduct a competitive procurement. This acquisition is being conducted under guidelines set forth in FAR, Part 13, Simplified Acquisition Procedures. No written solicitation will be issued for this requirement. Anticipated award date is 29 March 1999. Posted 03/18/99 (I-SN310008). (0077)

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