A polarization sensitive bolometric receiver for observations of the cosmic microwave background

W. C. Jones, R. S. Bhatia, J. J. Bock, A. E. Lange

Research output: Contribution to journalConference article

40 Scopus citations

Abstract

We have developed a bolometric receiver that is intrinsically sensitive to linear polarization for the purpose of making measurements of the polarization of the cosmic microwave background radiation. The receiver consists of a pair of co-located silicon nitride micromesh absorbers which couple anisotropically to linearly polarized radiation through a corrugated waveguide structure. This system allows background limited, simultaneous measurement of the Stokes I and Q parameters over ∼ 30% bandwidths at frequencies from ∼ 60 to 600 GHz. Since both linear polarizations traverse identical optical paths from the sky to the point of detection, the susceptibility to systematic effects is minimized. The amount of uncorrelated noise between the two polarization senses is limited to the quantum limit of thermal and photon shot noise, while drifts in the relative responsivity to orthogonal polarizations are limited to the effect of non-uniformity in the thin film deposition of the leads and the intrinsic thermistor properties. Devices using NTD Ge thermistors have achieved NEPs of 2 · 10-17 W/√Hz with a 1/f knee below 100 mHz at a base temperature of 270 mK. Numerical modelling of the structures has been used to optimize the bolometer geometry and coupling to optics. Comparisons of numerical results and experimental data are made. A description of how the quantities measured by the device can be interpreted in terms of the Stokes parameters is presented. The receiver developed for the Boomerang and Planck HFI focal planes is presented in detail.

Original languageEnglish (US)
Pages (from-to)227-238
Number of pages12
JournalProceedings of SPIE - The International Society for Optical Engineering
Volume4855
DOIs
StatePublished - 2002
EventMillimeter and Submillimeter Detectors for Astronomy - Waikaloa, HI, United States
Duration: Aug 25 2002Aug 28 2002

All Science Journal Classification (ASJC) codes

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

Keywords

  • Bolometers
  • Cosmic microwave background polarization
  • Cosmology
  • Sub-mm detectors

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