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Proceedings Paper

A large free-standing wire grid for microwave variable-delay polarization modulation
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Paper Abstract

One technique for mapping the polarization signature of the cosmic microwave background uses large, polarizing grids in reflection. We present the system requirements, the fabrication, assembly, and alignment procedures, and the test results for the polarizing grid component of a 50 cm clear aperture, Variable-delay Polarization Modulator (VPM). This grid is being built and tested at the Goddard Space Flight Center as part of the Polarimeter for Observing Inflationary Cosmology at the Reionization Epoch (POINCARE). For the demonstration instrument, 64 μm diameter tungsten wires are being assembled into a 200 μm pitch, free-standing wire grid with a 50 cm clear aperture, and an expected overall flatness better than 30 μm. A rectangular, aluminum stretching frame holds the wires with sufficient tension to achieve a minimum resonant frequency of 185 Hz, allowing VPM mirror translation frequencies of several Hz. A lightly loaded, flattening ring with a 50 cm inside diameter rests against the wires and brings them into accurate planarity.

Paper Details

Date Published: 9 July 2008
PDF: 12 pages
Proc. SPIE 7014, Ground-based and Airborne Instrumentation for Astronomy II, 70142A (9 July 2008); doi: 10.1117/12.787979
Show Author Affiliations
G. M. Voellmer, NASA Goddard Space Flight Ctr. (United States)
C. Bennett, Johns Hopkins Univ. (United States)
D. T. Chuss, NASA Goddard Space Flight Ctr. (United States)
J. Eimer, Johns Hopkins Univ. (United States)
H. Hui, Oregon State Univ. (United States)
S. H. Moseley, NASA Goddard Space Flight Ctr. (United States)
G. Novak, Northwestern Univ. (United States)
E. J. Wollack, NASA Goddard Space Flight Ctr. (United States)
L. Zeng, Johns Hopkins Univ. (United States)

Published in SPIE Proceedings Vol. 7014:
Ground-based and Airborne Instrumentation for Astronomy II
Ian S. McLean; Mark M. Casali, Editor(s)

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