Measurements of Infrared Sources with the Missile Defense Transfer Radiometer

The Missile Defense Transfer Radiometer (MDXR) was designed to calibrate infrared collimated and flood sources over the fW/cm^2 to uW/cm^2 power range from 3 um to 28 um in wavelength. The MDXR can operate in three different modes: as a filter radiometer, a Fourier-transform spectrometer (FTS)-based spectroradiometer, and as an absolute cryogenic radiometer (ACR). Since 2010, the MDXR has been used to make measurements of the collimated infrared irradiance at the output port of five different infrared test chambers at several facilities. We present a selection of results from these calibration efforts compared to signal predictions from the respective chamber models, as measured by the three different MDXR calibration modes. We also compare the results to previous measurements made of the same chambers with the NIST BXR. In general, the results are found to agree within their combined uncertainties, with the MDXR having lower uncertainty and greater spectral coverage. The FTS spectroradiometer in the MDXR has also been used to characterize the spectral output of monochromator sources located in test chambers