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 et al. (11 more) A&A, 520 (2010) A11 Published online: 15 September 2010 DOI: 10.1051/0004-6361/200913039