The POLARBEAR Fourier Transform Spectrometer Calibrator and Spectroscopic Characterization of the POLARBEAR Instrument

Abstract

We describe the Fourier Transform Spectrometer (FTS) used for in-field testing of the POLARBEAR receiver, an experiment located in the Atacama Desert of Chile which measures the cosmic microwave background (CMB) polarization. The POLARBEAR-FTS (PB-FTS) is a Martin-Puplett interferometer designed to couple to the Huan Tran Telescope (HTT) on which the POLARBEAR receiver is installed. The PB-FTS measured the spectral response of the POLARBEAR receiver with signal-to-noise ratio (SNR) $>20$ for $\sim$69% of the focal plane detectors due to three features: a high throughput of 15.1 steradian cm${}^2$, optimized optical coupling to the POLARBEAR optics using a custom designed output parabolic mirror, and a continuously modulated output polarizer. The PB-FTS parabolic mirror is designed to mimic the shape of the 2.5 m-diameter HTT primary reflector which allows for optimum optical coupling to the POLARBEAR receiver, reducing aberrations and systematics. One polarizing grid is placed at the output of the PB-FTS, and modulated via continuous rotation. This modulation allows for decomposition of the signal into different harmonics that can be used to probe potentially pernicious sources of systematic error in a polarization-sensitive instrument. The high throughput and continuous output polarizer modulation features are unique compared to other FTS calibrators used in the CMB field. In-field characterization of the POLARBEAR receiver was accomplished using the PB-FTS in April 2014. We discuss the design, construction, and operation of the PB-FTS and present the spectral characterization of the POLARBEAR receiver. We introduce future applications for the PB-FTS in the next-generation CMB experiment, the Simons Array.

References in corpus (12)

• A Joint Analysis of BICEP2/Keck Array and Planck Data
• The Quest for B Modes from Inflationary Gravitational Waves
• A Measurement of the Cosmic Microwave Background B-Mode Polarization Power Spectrum at Sub-Degree Scales with POLARBEAR
• A Measurement of the Cosmic Microwave Background $B$-Mode Polarization Power Spectrum at Sub-Degree Scales from 2 years of POLARBEAR Data
• The POLARBEAR Experiment
• The bolometric focal plane array of the Polarbear CMB experiment
• The bispectrum of polarized galactic foregrounds
• The POLARBEAR-2 and Simons Array Focal Plane Fabrication Status
• 2017 upgrade and performance of BICEP3: a 95GHz refracting telescope for degree-scale CMB polarization
• Design and Deployment of a Multichroic Polarimeter Array on the Atacama Cosmology Telescope
• Optical Characterization of the SPT-3G Focal Plane
• Common-mode rejection in Martin-Puplett spectrometers for astronomical observations at mm-wavelengths

Cited by in corpus (8)

• The Simons Observatory: Galactic Science Goals and Forecasts
• Framework for analysis of next generation, polarised CMB data sets in the presence of galactic foregrounds and systematic effects
• Requirements for future CMB satellite missions: photometric and band-pass response calibration
• The Simons Observatory: impact of bandpass, polarization angle and calibration uncertainties on small-scale power spectrum analysis
• Design and performance of a multi-terahertz Fourier transform spectrometer for axion dark matter experiments
• Characterization of a half-wave plate for cosmic microwave background circular polarization measurement with POLARBEAR
• A measurement of atmospheric circular polarization with POLARBEAR
• Requirements on bandpass resolution and measurement precision for LiteBIRD