Wide-field-of-view millimeter-wave telescope design with ultra-low cross-polarization

Bruce E. Bernacki; James F. Kelly; David Sheen; Brian Hatchell; Patrick Valdez; Jonathan Tedeschi; Thomas Hall; Douglas McMakin

doi:10.1117/12.917773

8 May 2012 Wide-field-of-view millimeter-wave telescope design with ultra-low cross-polarization

Bruce E. Bernacki, James F. Kelly, David Sheen, Brian Hatchell, Patrick Valdez, Jonathan Tedeschi, Thomas Hall, Douglas McMakin

Author Affiliations +

Proceedings Volume 8362, Passive and Active Millimeter-Wave Imaging XV; 836207 (2012) https://doi.org/10.1117/12.917773
Event: SPIE Defense, Security, and Sensing, 2012, Baltimore, Maryland, United States

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.

Citation Download Citation

Bruce E. Bernacki, James F. Kelly, David Sheen, Brian Hatchell, Patrick Valdez, Jonathan Tedeschi, Thomas Hall, and Douglas McMakin "Wide-field-of-view millimeter-wave telescope design with ultra-low cross-polarization", Proc. SPIE 8362, Passive and Active Millimeter-Wave Imaging XV, 836207 (8 May 2012); https://doi.org/10.1117/12.917773

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