@inproceedings{9f3942eb9f084b8ea3be0c50af61c315,
title = "Optical performance of the BICEP2 Telescope at the South Pole",
abstract = "Bicep2 deployed to the South Pole during the 2009-2010 austral summer, and is now mapping the polarization of the cosmic microwave background (CMB), searching for evidence of inflationary cosmology. Bicep2 belongs to a new class of telescopes including Keck (ground-based) and Spider (balloon-borne) that follow on Bicep's strategy of employing small, cold, on-axis refracting optics. This common design provides key advantages ideal for targeting the polarization signature from inflation, including: (i) A large field of view, allowing substantial light collecting power despite the small aperture, while still resolving the degree-scale polarization of the CMB; (ii) liquid helium-cooled optics and cold stop, allowing for low, stable instrument loading; (iii) the ability to rotate the entire telescope about the boresight; (iv) a baffled primary aperture, reducing sidelobe pickup; and (v) the ability to characterize the far field optical performance of the telescope using ground-based sources. We describe the last of these advantages in detail, including our efforts to measure the main beam shape, beammatch between orthogonally-polarized pairs, polarization efficiency and response angle, sidelobe pickup, and ghost imaging. We do so with ground-based polarized microwave sources mounted in the far field as well as with astronomical calibrators. Ultimately, Bicep2's sensitivity to CMB polarization from inflation will rely on precise calibration of these beam features.",
keywords = "Bicep, Bicep2, Cosmic microwave background, Keck, Polarization, Spider",
author = "Aikin, {Randol W.} and Ade, {P. A.} and S. Benton and Bock, {J. J.} and Bonetti, {J. A.} and Brevik, {J. A.} and Dowell, {C. D.} and L. Duband and Filippini, {J. P.} and Golwala, {S. R.} and M. Halpern and Hristov, {V. V.} and K. Irwin and Kaufman, {J. P.} and Keating, {B. G.} and Kovac, {J. M.} and Kuo, {C. L.} and Lange, {A. E.} and Netterfield, {C. B.} and Nguyen, {H. T.} and {Ogburn Iv}, {R. W.} and A. Orlando and C. Pryke and S. Richter and Ruhl, {J. E.} and Runyan, {M. C.} and C. Sheehy and Stokes, {S. A.} and R. Sudiwala and Teply, {G. P.} and Tolan, {J. E.} and Turner, {A. D.} and P. Wilson and Wong, {C. L.}",
year = "2010",
doi = "10.1117/12.857868",
language = "English (US)",
isbn = "9780819482310",
series = "Proceedings of SPIE - The International Society for Optical Engineering",
booktitle = "Millimeter, Submillimeter, and Far-Infrared Detectors and Instrumentation for Astronomy V",
note = "Millimeter, Submillimeter, and Far-Infrared Detectors and Instrumentation for Astronomy V ; Conference date: 29-06-2010 Through 02-07-2010",
}