Experiments to measure the polarization of the CMB require an exquisite characterization and control of optical systematics to achieve their scientific goals. Relevant parameters are the polarized co- and cross-polar beam shape, absolute and relative polarization angle among detector pairs, polarization frequency dependence across the bandpass, and polarization properties of far sidelobes. In...
The BICEP/Keck telescopes are a suite of CMB polarimeters located at the South Pole searching for evidence of inflationary gravitational waves. We invest much of our effort in acquiring high-fidelity calibrations of the optical performance to mitigate systematics in our results. To that end, we map far-field optical response using ground-based, non-thermal, finely-polarized Broad Spectrum...
Calibrating raw detector time-ordered data (TOD) to a standard unit is often the first step in processing data sets acquired by large arrays of detectors over many months of observations. The calibration method must be accurate, to suppress systematic errors in the final results, and robust, to be applicable to a vast majority of observations.
The raw calibration method developed for the CLASS...
The LiteBIRD Low Frequency Telescope (LFT) is a crossed-Dragone telescope that observes 34-161 GHz with a field of view of 18 x 9 degrees. We developed a 1/4-scaled model of the LFT and measured its far-sidelobes and polarization angles at multiple positions on the focal plane at accordingly scaled wavelength. The near-field measurements were consistent with physical optics simulation down to...
