The High Frequency Instrument (HFI) onboard the Planck satellite use bolometric detectors cooled to 100mK to detect sub-millimeter and millimeter radiation. A Simplified functional block-diagram of HFI, from the radiation coming from the observed source to the data flow, is shown on the following figure:

The different sub-systems of HFI are described in this section. I hope you will find all answers to the questions you have on the HFI hardware. If it is not the case or if you have any comment, please do not hesitate to contact me (Michel Piat).