Characterization of argon arc source in the infrared

A wall-stabilized arc source is being investigated as a radiometric source for the near- and mid-infrared spectral range. This arc is similar to the argon mini-arc, which has been used as a radiometric source in the ultraviolet. The potential usefulness of the arc in the infrared (IR) range stems from its high brightness in this region. The arc has been tested as a source for a recently constructed facility for calibrating IR detectors. Over the range 3 µm to 11 µm, the signals with this source were greater by a factor of 6 to 17 than the signals from a 1500 K ceramic element, despite the beam from the arc being smaller in angular extent. The radiance of the source was calibrated from 1,6 µm to 10,6 µm via a 1140 K black body. Over most of this spectral range the radiance of the arc is equal to that of black bodies ranging in temperature from 5000 K to 10000 K. From 1 µm to 3 µm, a spectral scan with relatively high resolution shows a spectrum dominated by strong Ar I line emission. Finally, measurements were made of radiance as a function of arc current and translational position of the source.