title: Testing the radiometric accuracy of Fourier transform infrared transmittance measurements.
abstract: We have investigated the ordinate scale accuracy of ambient temperature transmittance measurements made with a Fourier transform infrared (FT-IR) spectrophotometer over the wavelength range of 2-10 mum. Two approaches are used: (1) measurements of Si wafers whose index of refraction are well known from 2 to 5 mum, in which case the FT-IR result is compared with calculated values; (2) comparison of FT-IR and laser transmittance measurements at 3.39 and 10.6 mum on nominally neutral-density filters that are free of etaloning effects. Various schemes are employed to estimate and reduce systematic error sources in both the FT-IR and laser measurements, and quantitative uncertainty analyses are performed.
authors.forename: S G
authors.initials: SG
authors.lastname: Kaplan
authors.forename: L M
authors.initials: LM
authors.lastname: Hanssen
authors.forename: R U
authors.initials: RU
authors.lastname: Datla