As space instrument designs can be different so is the calibration. That means that in many cases a dedicated stimulus must be designed and built. For the on-ground calibration of a space instrument TNO has developed several optical stimuli to be able to acquire complete knowledge of the instrument behavior. Main aspects that are calibrated are:
Radiometric, using calibration standards (NIST) and special sources (sun simulator)
Polarization, using a low radiance stimulator
Wavelength calibration, using spectral line source(s) and lasers
Slit-function, using a dedicated stimulus
Stray-light, using monochromatic sources
Field of view, using narrow field sources (star stimulus)
Many of the instrument characteristics depend on the environment in which the instrument is operated. In case of space instruments this means in vacuum, within a certain temperature range and at zero gravity. Calibration is performed in a dedicated Thermal Vacuum Chamber at the Van Leeuwenhoek Laboratory of TNO in Delft.