Sidelobe Modeling and Mitigation for a Three Mirror Anastigmat Cosmic Microwave Background Telescope
arXiv:2302.10971 · doi:10.1364/AO.488454
Abstract
Telescopes measuring cosmic microwave background (CMB) polarization on large angular scales require exquisite control of systematic errors to ensure the fidelity of the cosmological results. In particular, far-sidelobe contamination from wide angle scattering is a potentially prominent source of systematic error for large aperture microwave telescopes. Here we describe and demonstrate a ray-tracing-based modeling technique to predict far sidelobes for a Three Mirror Anistigmat (TMA) telescope designed to observe the CMB from the South Pole. Those sidelobes are produced by light scattered in the receiver optics subsequently interacting with the walls of the surrounding telescope enclosure. After comparing simulated sidelobe maps and angular power spectra for different enclosure wall treatments, we propose a highly scattering surface that would provide more than an order of magnitude reduction in the degree-scale far-sidelobe contrast compared to a typical reflective surface. We conclude by discussing the fabrication of a prototype scattering wall panel and presenting measurements of its angular scattering profile.
arXiv comment14 pages, 8 figures
References in corpus (16)
- HEALPix -- a Framework for High Resolution Discretization, and Fast Analysis of Data Distributed on the Sphere
- BICEP / Keck XIII: Improved Constraints on Primordial Gravitational Waves using Planck, WMAP, and BICEP/Keck Observations through the 2018 Observing Season
- CMB-S4 Science Case, Reference Design, and Project Plan
- CMB-S4: Forecasting Constraints on Primordial Gravitational Waves
- Planck constraints on the tensor-to-scalar ratio
- SPTpol: an instrument for CMB polarization measurements with the South Pole Telescope
- Measurements of B-mode Polarization of the Cosmic Microwave Background from 500 Square Degrees of SPTpol Data
- XL-Calibur -- a second-generation balloon-borne hard X-ray polarimetry mission
- BICEP3 performance overview and planned Keck Array upgrade
- The Simons Observatory: Modeling Optical Systematics in the Large Aperture Telescope
- Two-year Cosmology Large Angular Scale Surveyor (CLASS) Observations: 40 GHz Telescope Pointing, Beam Profile, Window Function, and Polarization Performance
- Performance and on-sky optical characterization of the SPTpol instrument
- Far Sidelobes from Baffles and Telescope Support Structures in the Atacama Cosmology Telescope
- A Simulation-Based Method for Correcting Mode Coupling in CMB Angular Power Spectra
- Fabrication of a Monolithic 5-Meter Aluminum Reflector for Millimeter-Wavelength Observations of the Cosmic Microwave Background
- Modeling sidelobe response for ground-based mm-wavelength telescopes with the geometrical theory of diffraction