Wide-Field-of-View Millimeter-Wave Telescope Design with Ultra-Low Cross-Polarization
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 most 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 polarization crosstalk and a large diffraction-limited field of view well suited to millimeter-wave imaging arrays.
- Research Organization:
- Pacific Northwest National Lab. (PNNL), Richland, WA (United States)
- Sponsoring Organization:
- USDOE
- DOE Contract Number:
- AC05-76RL01830
- OSTI ID:
- 1092024
- Report Number(s):
- PNNL-SA-86574; NN2001000
- Resource Relation:
- Conference: Passive and Active Millimeter-Wave Imaging XV, April 23, 2012, Baltimore, Maryland. Proceedings of the SPIE, 8362:Paper No. 836207
- Country of Publication:
- United States
- Language:
- English
Similar Records
Fully Polarimetric Passive W-band Millimeter Wave Imager for Wide Area Search
Optical design concept of the CMB-S4 large-aperture telescopes and cameras