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Proceedings Paper

LSST detector module and raft assembly metrology concepts
Author(s): Peter Z. Takacs; Paul O'Connor; Veljko Radeka; George Mahler; James Frank; John Geary
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Paper Abstract

The LSST camera focal plane array will consist of individual Si sensor modules, each 42×42mm2 in size, that are assembled into 3×3 "raft" structures, which are then assembled into the final focal plane array. It is our responsibility at Brookhaven National Lab (BNL) to insure that the individual sensors provided by the manufacturer meet the flatness requirement of 5 μm PV and that the assembled raft structure be within the 6.5 μm PV flatness tolerance. These tolerances must be measured with the detectors operating in a cryogenic environment at -100C in a face-down configuration. Conventional interferometric techniques for flatness testing are inadequate to insure that edge discontinuities between detector elements are within the tolerances because of the quarter-wave phase ambiguity problem. For this reason we have chosen a combination of metrology techniques to solve the discontinuity ambiguity problem that include both a full aperture interferometer and a scanning confocal distance microscope. We will discuss concepts for performing flatness metrology testing with these instruments under these conditions and will present preliminary results of measurement sensitivity and repeatability from tests performed on step height artifacts.

Paper Details

Date Published: 6 July 2006
PDF: 7 pages
Proc. SPIE 6273, Optomechanical Technologies for Astronomy, 62733Q (6 July 2006); doi: 10.1117/12.673399
Show Author Affiliations
Peter Z. Takacs, Brookhaven National Lab. (United States)
Paul O'Connor, Brookhaven National Lab. (United States)
Veljko Radeka, Brookhaven National Lab. (United States)
George Mahler, Brookhaven National Lab. (United States)
James Frank, Brookhaven National Lab. (United States)
John Geary, Harvard Smithsonian (United States)


Published in SPIE Proceedings Vol. 6273:
Optomechanical Technologies for Astronomy
Eli Atad-Ettedgui; Joseph Antebi; Dietrich Lemke, Editor(s)

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