The FUV Calibration Facility is used for detector-based radiometry and other measurements of optical properties in the far ultraviolet (FUV) from 50 nm to 254 nm wavelength (5 eV to 25 eV photon energy).
The light source is a duoplasmatron - a hot-filament discharge confined in a magnetic field - which provides the characteristic emission spectrum of the neutral and singly ionized species of the source gas. The FUV Calibration Facility source can operate on H2, He, Ne, Ar, or Kr. The H2 discharge gives a rich spectrum of molecular lines and molecular continuum radiation in additional to the atomic emission. The radiation is monochromatised by a 1-m focal length, spherical-grating monochromator and the exit beam is passed into the experimental chamber.
Various experiment stations can be mounted at the output of the monochromator to enable different measurements. One station allows the interchange of two detectors in the beam to calibrate one against the other. A second allows the calibration of a detector against a double-plate ionization chamber. A third limits the size of the beam to allow uniformity scanning of a detector.