Spectral characterization of the Roman Space Telescope Grism and Prism assemblies

The Roman Space Telescope (RST) Wide Field Instrument (WFI) recently completed its thermal vacuum (TVAC) campaign in Boulder, CO. This campaign, which concludes multiple years of preparation, represented the last opportunity for characterization and verification of the Grism and Prism spectral properties before launch; currently scheduled for late-2026.

To this end, a highly-automated series of measurements were performed to acquire images of calibration spectra at many field points. Features that were measured during these efforts include dispersion scale, blue/red bandpass edges, diffraction order radiometry, and ghost images. A summary of the techniques and
results for several of these efforts is provided here.