The assessment of the performance of a Fourier Transform Spectrometer requires an extended source of rad-iance which is nearly flat cagier the spectral range of interest. It must also be sufficiently low in intensity not to saturate sensitive instruments. A collimated blackbody cannot meet these criteria. An integrating sphere will adequately provide the signal characteristics sought. Such a sphere is described for use in the 500 to 5000 cm-1 spectral range. It is cryogenically cooled to reduce self emissions and is gold coated to provide a high, constant throughput. The output radiance levels are described using a blackbody input. Descriptions of techniques to reduce this level are provided. The unit can also be used in conjunction with a monochromator to provide spectral lines useful for evaluating line profiles throughout the spectral region of use. A brief description is provided of the use of an ambient temperature sphere. This provided useful data in obtaining the spectral calibration of radiometers and in determining the responsivity of various instruments.
D. J. Lovell,
Dean F. Kimball,
"Instrumentation To Assess Interferometer Performance", Proc. SPIE 0191, Multiplex and/or High Throughput Spectroscopy, (29 October 1979); doi: 10.1117/12.957826; https://doi.org/10.1117/12.957826