Infrared Background Signature Survey Experiment (IBSS) Test Results Of The Optical Subsystem

The test results of the IBSS Optical Subsystem are presented. The newly developed instrument consists of a spectrometer and a radiometer together with a diffraction-limited telescope. The instrument is designed for remote measurements of infrared emissions aboard spacecraft and is cooled with supercritical helium to temperatures down to 5-20 K in order to suppress the self-emission of the instrument. The optical layout of the telescope is optimized for high straylight rejection of the earth's radiation and for for good image quality, which is required for spatial observations. The performance data of the instrument, i.e. image quality, detector performance data, and spectral resolution were verified by several cooling cycles.