Optical characterization of the BICEP3 CMB polarimeter at the South Pole

K. S. Karkare, P. A.R. Ade, Z. Ahmed, K. D. Alexander, M. Amiri, D. Barkats, S. J. Benton, C. A. Bischoff, J. J. Bock, H. Boenish, R. Bowens-Rubin, I. Buder, E. Bullock, V. Buza, J. Connors, J. P. Filippini, S. T. Fliescher, J. A. Grayson, M. Halpern, S. A. HarrisonG. C. Hilton, V. V. Hristov, H. Hui, K. D. Irwin, J. H. Kang, E. Karpel, S. Kefeli, S. A. Kernasovskiy, J. M. Kovac, C. L. Kuo, E. M. Leitch, M. Lueker, K. G. Megerian, V. Monticue, T. Namikawa, C. B. Netterfield, H. T. Nguyen, R. O'Brient, R. W. Ogburn, C. L. Pryke, C. D. Reintsema, S. Richter, M. T. St Germaine, R. Schwarz, C. D. Sheehy, Z. K. Staniszewski, B. Steinbach, G. P. Teply, K. L. Thompson, J. E. Tolan, C. Tucker, A. D. Turner, A. G. Vieregg, A. Wandui, A. Weber, J. Willmert, C. L. Wong, W. L.K. Wu, K. W. Yoon

Research output: Chapter in Book/Report/Conference proceedingConference contribution

13 Scopus citations


BICEP3 is a small-aperture refracting cosmic microwave background (CMB) telescope designed to make sensitive polarization maps in pursuit of a potential B-mode signal from inflationary gravitational waves. It is the latest in the Bicep/Keck Array series of CMB experiments located at the South Pole, which has provided the most stringent constraints on inflation to date. For the 2016 observing season, BICEP3 was outfitted with a full suite of 2400 optically coupled detectors operating at 95 GHz. In these proceedings we report on the far field beam performance using calibration data taken during the 2015-2016 summer deployment season in situ with a thermal chopped source. We generate high-fidelity per-detector beam maps, show the array-averaged beam profile, and characterize the differential beam response between co-located, orthogonally polarized detectors which contributes to the leading instrumental systematic in pair differencing experiments. We find that the levels of differential pointing, beamwidth, and ellipticity are similar to or lower than those measured for Bicep2 and Keck Array. The magnitude and distribution of Bicep3's differential beam mismatch - and the level to which temperature-to-polarization leakage may be marginalized over or subtracted in analysis - will inform the design of next-generation CMB experiments with many thousands of detectors.

Original languageEnglish (US)
Title of host publicationMillimeter, Submillimeter, and Far-Infrared Detectors and Instrumentation for Astronomy VIII
EditorsJonas Zmuidzinas, Wayne S. Holland
ISBN (Electronic)9781510602076
StatePublished - 2016
EventMillimeter, Submillimeter, and Far-Infrared Detectors and Instrumentation for Astronomy VIII - Edinburgh, United Kingdom
Duration: Jun 28 2016Jul 1 2016

Publication series

NameProceedings of SPIE - The International Society for Optical Engineering
ISSN (Print)0277-786X
ISSN (Electronic)1996-756X


OtherMillimeter, Submillimeter, and Far-Infrared Detectors and Instrumentation for Astronomy VIII
Country/TerritoryUnited Kingdom

All Science Journal Classification (ASJC) codes

  • Electronic, Optical and Magnetic Materials
  • Condensed Matter Physics
  • Computer Science Applications
  • Applied Mathematics
  • Electrical and Electronic Engineering


  • Cosmic microwave background
  • Gravitational waves
  • Inflation
  • Polarization


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