Planck pre-launch status: The optical architecture of the HFI

P. A.R. Ade, G. Savini, R. Sudiwala, C. Tucker, A. Catalano, S. Church, R. Colgan, F. X. Desert, E. Gleeson, W. C. Jones, J. M. Lamarre, A. Lange, Y. Longval, B. Maffei, J. A. Murphy, F. Noviello, F. Pajot, J. L. Puget, I. Ristorcelli, A. WoodcraftV. Yurchenko

Research output: Contribution to journalArticlepeer-review

30 Scopus citations


The Planck High Frequency Instrument, HFI, has been designed to allow a clear unobscured view of the CMB sky through an off- axis Gregorian telescope. The prime science target is to measure the polarized anisotropy of the CMB with a sensitivity of 1 part in 106 with a maximum spatial resolution of 5 arcmin (Cl ∼ 3000) in four spectral bands with two further high-frequency channels measuring total power for foreground removal. These requirements place critical constraints on both the telescope configuration and the receiver coupling and require precise determination of the spectral and spatial characteristics at the pixel level, whilst maintaining control of the polarisation. To meet with the sensitivity requirements, the focal plane needs to be cooled with the optics at a few Kelvin and detectors at 100 mK. To limit inherent instrumental thermal emission and diffraction effects, there is no vacuum window, so the detector feedhorns view the telescope secondary directly. This requires that the instrument is launched warm with the cooler chain only being activated during its cruise to L2. Here we present the novel optical configuration designed to meet with all the above criteria.

Original languageEnglish (US)
Article numberA11
JournalAstronomy and Astrophysics
Issue number1
StatePublished - Sep 15 2010

All Science Journal Classification (ASJC) codes

  • Astronomy and Astrophysics
  • Space and Planetary Science


  • cosmic microwave background
  • instrumentation: detectors
  • instrumentation: polarimeters
  • space vehicles: instruments
  • submillimeter: general
  • techniques: photometric


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