Optical design for the Submillimeter and Far InfraRed Experiment (SAFIRE)

The SAFIRE, the Submillimeter and Far InfraRed Experiment, was designed for interstellar physics in the airborne Observatory SOFIA. SAFIRE is a cryogenic Echelle Grating spectrograph for covering 27 to 470 microns, with R ranging from 2-6,000. Here we will discuss the details of the optical design, the design process, and the performance of the instrument.