Verification of the optical system performance of FIFI-LS: the Field-Imaging Far-Infrared Line Spectrometer for SOFIA

FIFI-LS is a Field-Imaging Line Spectrometer designed for the SOFIA airborne observatory. The instrument will operate in the far infrared (FIR) wavelength range from 42 to 210 μm. Two spectrometers operating between 42-110 μm and 110-210 μm allow simultaneous and independent diffraction limited 3D imaging over a field of view of 6" × 6" and 12" × 12" respectively. We have developed a telescope simulator to test the imaging and spectral performance of FIFI-LS in the FIR. Here, we present the telescope simulator as well as the performance verification of FIFI-LS using the simulator. Finally we compare the measurements with the theoretical expected performance of FIFI-LS.