High-performance detector read-out at very low temperatures

An infra-red detection system must be physically colder than the objects it needs to observe. As some of the objects to be observed by the European Space Agency´s Infra-red Space Observatory (ISO) might be as cold as a few tens of degrees Kelvin, it is essential that the ISO´s detectors should themselves operate at temperatures close to absolute zero. To avoid problems with electromagnetic interference, it is also necessary that detector read-out (i.e. first-stage signal amplification) be located as close as possible to the detectors. As conventional amplifiers cannot work at temperatures close to absolute zero, special techniques had to be used for the ISO´s detectors