Testing and Improving the Radiometric Accuracy of FT-IR Transmittance Measurements

Abstract

While FT-IR spectrophotometers have clear advantages over dispersive instruments in throughput and signal averaging, the same design elements that give these advantages can produce more complicated and severe sources of radiometric error in FTIR spectra compared to their dispersive counterparts. However, the high signal-to-noise ratio and good measurement repeatability afforded by FT-IR spectrophotometers are sometimes misinterpreted as low absolute radiometric uncertainty. While the complete radiometric characterization of even one FT-IR instrument is an ambitious long-term goal, it should be possible for users to both understand and reduce the various sources of radiometric error through the use of standard and diagnostic samples appropriate to the measurements of interest.