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Proceedings Paper

Optical properties of dielectrics in the mm range: the case of spurious polarization induced by a vacuum window
Author(s): Claudio Macculi; Stefano Cortiglioni; Ettore Carretti; Mario Zannoni; Oscar A. Peverini; Riccardo Tascone; Augusto Olivieri
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Paper Abstract

The noise of radioastronomy receivers is usually kept low by cooling the front-end into cryostats, where the internal and the external environments are interfaced by optical windows. Such dielectric windows can sistematically correlate the incoming unpolarized radiation and decorrelate its polarized component. Here, we present a study on the effects of dielectrics in high sensitivity microwave polarimetry, including a model of the induced spurious polarization, a selection of materials in term of their optical properties as well as measurements of their optical parameters. The interesting result is that isotropic dielectrics can produce spurious polarization both when transmit anisotropic diffuse radiation or are not thermally uniform. Finally, such a model can be used to design a calibrator which generates very low polarized signal.

Paper Details

Date Published: 8 October 2004
PDF: 12 pages
Proc. SPIE 5498, Millimeter and Submillimeter Detectors for Astronomy II, (8 October 2004); doi: 10.1117/12.551753
Show Author Affiliations
Claudio Macculi, CNR-ISAF Bologna (Italy)
Stefano Cortiglioni, CNR-ISAF Bologna (Italy)
Ettore Carretti, CNR-ISAF Bologna (Italy)
Mario Zannoni, CNR-ISAF Milano (Italy)
Oscar A. Peverini, CNR-IEIIT Torino (Italy)
Riccardo Tascone, CNR-IEIIT Torino (Italy)
Augusto Olivieri, CNR-IEIIT Torino (Italy)


Published in SPIE Proceedings Vol. 5498:
Millimeter and Submillimeter Detectors for Astronomy II
Jonas Zmuidzinas; Wayne S. Holland; Stafford Withington, Editor(s)

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