Photodiode and inteference filter calibration using a monochromatic illumination and cryogenic calibration system

The SNAP mission will conduct a systematic error limited survey of Type Ia supernovae to measure dark energy in the universe. The final accuracy of the dark energy parameters will depend upon the calibration of the flight instrumentation. To perform ground-based characterizations of SNAP calibration hardware, we have built the Monochromatic Illumination and Cryogenic Calibration System (MICCS). There are two immediate purposes for MICCS. The first purpose is to transfer the NIST irradiance calibration of Si and InGaAs photodiodes to additional photodiodes that are operated at the nominal SNAP focal plane temperature of 140 K. These photodiodes will be used by detector characterization laboratories to measure the quantum efficiency of the SNAP flight detectors. The second purpose of MICCS is to characterize the transmission of interference filters at incident angles and temperature similar to that used on the SNAP focal plane. We examine periodic transmission variations in a set of commercial filters and develop an interpolation method to determine the filter bandpass at any angle relevant to the SNAP focal plane.