A new source-based radiometry beamline was recently constructed at the Synchrotron Ultraviolet Radiation Facility (SURF III). The goal of this beamline is to establish a national source standard with a wide spectral range from the far ultraviolet to the infrared by using the calculability of SURF III. The new beamline is a straight-through white-light beamline with few, if any, optical componen...