We summarize the fabrication, flight qualification, and dark performance of bolometers completed at the Jet Propulsion Laboratory for the High Frequency Instrument (HFI) of the joint ESA/NASA Herschel/ Planck mission to be launched in 2009. The HFI is a multicolor focal plane which consists of 52 bolometers operated at 100 mK. Each bolometer is mounted to a feedhorn-filter assembly which defines one of six frequency bands centered between 100-857 GHz. Four detectors in each of five bands from

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... 3-857 GHz are coupled to both linear polarizations and thus measure the total intensity. In addition, eight detectors in each of four bands (100, 143, 217, and 353 GHz) couple only to a single linear polarization and thus provide measurements of the Stokes parameters, Q and U, as well as the total intensity. The measured noise equivalent power (NEP) of all detectors is at or below the background limit for the telescope and time constants are a few ms, short enough to resolve point sources as the 5 to 9 arc min beams move across the sky at 1 rpm. and 857 GHz. The PSBs, similarly, are mounted to feedhorns with bandpass filters that define four bands centered at 100, 143, 217, and 353 GHz. The SWB and PSBs in each band have a detector noise equivalent power (NEP) so that the in flight sensitivity is limited by the photon noise, in Fig. 1 , which is the quadrature sum of contributions from the background produced by the sky, the cold telescope, and the cryogenic filter stages in the instrument. Each bolometer, feedhorn, and filter assembly, cooled to 100 mK, is mounted at the focal plane of a telescope with 9, 7, and 5 arc min resolution for the bands 100, 143, and ≥217 GHz, respectively. The spacecraft samples the sky by spinning at 1 rpm at its orbit at the Earth-Sun L2 Lagrange point. The response time τ of all bolometers, summarized in Fig. 2 , is fast enough to resolve point sources at the resolution of the telescope. Here we report on the completion of the build,