A DC-coupled, high sensitivity bolometric detector system for the infrared telescope in space

The performance of an AC bridge readout system that has been developed for use on the infrared telescope in space is described. The AC bridge readout provides excellent DC stability, allowing observing strategies well suited to spaceborne observations. The ability to modulate the optical signal slowly allows the use of highly sensitive, long time-constant bolometers. At 300 mK, the bolometers have an electrical noise equivalent power of 3*10/sup -17/ W/ square root Hz. The total noise of the differential signal, including amplifier noise, is less than 8*10/sup -17/ W/ square root Hz at frequencies as low as 35 mHz.<
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