ISOPHOT calibration facility and pre-flight characterization

摘要

A calibration facility simulating the optical and cryogenic environment of the ISO satellite has been built for characterizing the ISOPHOT instrument. This facility uses a commercially calibrated, 900 K - blackbody radiation source and an optics at room temperature to provide an f/15 beam to the instrument which is contained in a LHe-cryostat. The low level infrared flux levels of ISO are obtained by use of a light sealed instrument chamber and cold attenuation filters. The infrared flux can be calculated using the known blackbody emission and the cold calibrated transmission spectra of the filters. The calibration facility further provides a scanning mechanism, a light modulator and filters for polarization measurements and wavelength calibrations of the ISOPHOT spectrometer channels. Electrical support equipment for the instrument operation and software for data archiving and analysis have been customized for this project. The test program comprised a standardized acceptance test for the entire instrument and special tests addressing individual instrument properties. The data obtained contain the photometric sensitivities of ISOPHOT, optimized instrument settings, reference data for the integrated system tests and inputs for the ongoing mission planning.