Low-cost remote sensing instruments for atmospheric trace species and improvements in radiometric calibration

Comparisons of a new class of ultra stable ion-assisted-deposition (IAD) narrow band interference filters fabricated from thin films of refractory metal oxides and SiO2 have produced "hard" filters which are radiometrically stable under conditions of extreme environmental stress such as high temperature, humidity, and space. The new IAD interference filter technology can be used to derive detector-based radiometric scales with significantly smaller uncertainties than a source-based radiometric calibration scale. For the ultraviolet, 250 to 400 nm, a calibration transfer spectroradiometer consisting of a small tandem Ebert-Fastie double monochromator and a multifilter spectroradiometer consisting of a series of narrow band IAD filters combined with a NIST quantum efficiency silicon photodiode for the ultraviolet should be capable of defining a detector-based radiometric calibration scale with uncertainties < 1.0%. The double monochromator and the filter calibration transfer standard spectroradiometer have been used to investigate the radiometric uncertainty and repeatability of three radiance sources; a FEL lamp-diffuser, a xenon are-diffuser, and the aperture of an internally illuminated sphere.