Aikin, Randol W. and Bock, J. J. and Brevik, J. A. and Dowell, C. D. and Filippini, J. P. and Golwala, S. R. and Hristov, V. V. and Lange, A. E. and Nguyen, H. T. and Orlando, A. and Richter, S. and Runyan, M. C. and Teply, G. P. (2010) Optical Performance of the BICEP2 Telescope at the South Pole. In: Millimeter, Submillimeter, and Far-Infrared Detectors and Instrumentation for Astronomy V. Proceedings of SPIE (7741). Society of Photo-optical Instrumentation Engineers (SPIE) , Bellingham, WA, Art. No. 77410V. ISBN 978-0-81948-231-0 http://resolver.caltech.edu/CaltechAUTHORS:20110311-145009599
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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 the Keck Array (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, beam-match 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.
|Item Type:||Book Section|
|Additional Information:||© 2010 SPIE. Bicep2 has been made possible by support from the National Science Foundation, Grant No. ANT-0742818. Detector development has been made possible by the generous support of the Gordon and Betty Moore Foundation. We are grateful to have Steffen Richter as our 2010 South Pole winterover. The Bicep2 team would also like to thank the South Pole Station staff for logistical support. We thank our Bicep, Keck, and Spider colleagues for useful discussions and shared expertise. Finally we wish to thank Barbara Wertz and Kathy Deniston for their tireless logistical and administrative support.|
|Subject Keywords:||BICEP; BICEP2; Keck; Spider; Cosmic microwave background; Polarization|
|Official Citation:||Randol W. Aikin, P. A. Ade, S. Benton, J. J. Bock, J. A. Bonetti, J. A. Brevik, C. D. Dowell, L. Duband, J. P. Filippini, S. R. Golwala, M. Halpern, V. V. Hristov, K. Irwin, J. P. Kaufman, B. G. Keating, J. M. Kovac, C. L. Kuo, A. E. Lange, C. B. Netterfield, H. T. Nguyen, R. W. Ogburn IV, A. Orlando, C. Pryke, S. Richter, J. E. Ruhl, M. C. Runyan, C. Sheehy, S. A. Stokes, R. Sudiwala, G. P. Teply, J. E. Tolan, A. D. Turner, P. Wilson and C. L. Wong, "Optical performance of the BICEP2 Telescope at the South Pole", Proc. SPIE 7741, 77410V (2010); doi:10.1117/12.857868|
|Usage Policy:||No commercial reproduction, distribution, display or performance rights in this work are provided.|
|Deposited By:||Ruth Sustaita|
|Deposited On:||15 Mar 2011 15:07|
|Last Modified:||26 Dec 2012 13:01|
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