An Optical Test Facility for the B-BOP Bolometers of the SPICA Mission

The B-BOP instrument developed for the SPICA observatory will use a new generation of submillimeter in pixel polarization sensitive bolometers cooled at 50mK. An ultra-low background testbed for these bolometers has been developed for the M5 phase A at ESA. The main challenge is there to combine a very low flux on the detectors (ifW) a "flat" spectrum around 100 mu m, and a very high dynamic range (up to 10 pW), in the volume of a commercial dilution cryostat. All these constraints were achieved by the use of an inverted telescope optics that dilutes a multi emitter source through a rotatice polariser. This allowed us to perform the first measurements on bolometer arrays produced by CEA-Leti.