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Measurement of Small Apertures



James A. Fedchak, Adriaan C. Carter, Raju V. Datla


The Low Background Infrared calibration (LBIR) facility at the National Institute of Standards and Technology (NIST) is developing a relative aperture area instrument to measure the areas of apertures with diameters ranging from 5 mm to 0.05 mm. NIST already has the capability of determining the absolute area of apertures with diameters larger than 0.35 mm. The goal of the LBIR facility is to achieve a standard uncertainty of better than 0.1%. We report on the current status of this effort and plans for improvement. We are near the goal for apertures larger than 0.350 mm.


Aperture Area Measurement, blackbody, calibration, LBIR, radiometry


Fedchak, J. , Carter, A. and Datla, R. (2006), Measurement of Small Apertures, Metrologia, [online],, (Accessed May 30, 2024)


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Created March 22, 2006, Updated October 12, 2021