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Proceedings Paper

Wide-field-of-view millimeter-wave telescope design with ultra-low cross-polarization
Author(s): Bruce E. Bernacki; James F. Kelly; David Sheen; Brian Hatchell; Patrick Valdez; Jonathan Tedeschi; Thomas Hall; Douglas McMakin
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Paper Abstract

As millimeter-wave arrays become available, off-axis imaging performance of the fore optics increases in importance due to the relatively large physical extent of the arrays. Typically, simple optical telescope designs are adapted to millimeter-wave imaging but single-mirror spherical or classic conic designs cannot deliver adequate image quality except near the optical axis. Since millimeter-wave designs are quasi-optical, optical ray tracing and commercial design software can be used to optimize designs to improve off-axis imaging as well as minimize cross-polarization. Methods that obey the Dragone-Mizuguchi condition for the design of reflective millimeter-wave telescopes with low cross-polarization also provide additional degrees of freedom that offer larger fields of view than possible with single-reflector designs. Dragone's graphical design method does not lend itself readily to computer-based optical design approaches, but subsequent authors expanded on Dragone's geometric design approach with analytic expressions that describe the location, shape, off-axis height and tilt of the telescope elements that satisfy Dragone's design rules and can be used as a first-order design for subsequent computer-based design and optimization. We investigate two design variants that obey the Dragone-Mizuguchi conditions that exhibit ultra-low cross-polarization and a large diffraction-limited field of view well suited to millimeter-wave imaging arrays.

Paper Details

Date Published: 8 May 2012
PDF: 11 pages
Proc. SPIE 8362, Passive and Active Millimeter-Wave Imaging XV, 836207 (8 May 2012); doi: 10.1117/12.917773
Show Author Affiliations
Bruce E. Bernacki, Pacific Northwest National Lab. (United States)
James F. Kelly, Pacific Northwest National Lab. (United States)
David Sheen, Pacific Northwest National Lab. (United States)
Brian Hatchell, Pacific Northwest National Lab. (United States)
Patrick Valdez, Pacific Northwest National Lab. (United States)
Jonathan Tedeschi, Pacific Northwest National Lab. (United States)
Thomas Hall, Pacific Northwest National Lab. (United States)
Douglas McMakin, Pacific Northwest National Lab. (United States)


Published in SPIE Proceedings Vol. 8362:
Passive and Active Millimeter-Wave Imaging XV
David A. Wikner; Arttu R. Luukanen, Editor(s)

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