NIST - National Institute of Standards and Technology
09/01/2026 | Press release | Distributed by Public on 09/02/2026 03:30
Optical Measurement of Radiometric Aperture Areas
Published
September 1, 2026
Author(s)
Ulf Griesmann
Abstract
The National Institute of Standards and Technology (NIST) calibrates the areas of radiometric and photometric apertures using an optical coordinate measuring machine, which provides direct traceabililty of aperture areas to the length unit meter of the International System of Units (SI). This measurement system combines a two-dimensional motion stage with laser interferometers for position feedback, and a high-magnification optical transmission microscope. For area measurements, apertures are mounted on the motion stage in the focal plane of an illuminator. The microscope is then used to locate points on the edge of the apertures in the coordinate system of the motion stage. The aperture area is calculated from a set of aperture edge positions that have been measured along the full length of an aperture's edge. This publication describes the measurement instrument, provides a summary of the general measurement procedure, and it documents the software algorithms that are applied in the measurements. The traceability of aperture area measurements to the SI, and the components of measurement uncertainty that contribute to the total measurement uncertainty stated in the calibration reports are explained.
Citation
Special Publication (NIST SP) - 250-102
Report Number
250-102
NIST Pub Series
Pub Type
NIST Pubs
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Keywords
radiometric apertures, aperture area, laser interferometry, optical microscopy, optical coordinate measuring machine
Citation
Griesmann, U. (2026), Optical Measurement of Radiometric Aperture Areas, Special Publication (NIST SP), National Institute of Standards and Technology, Gaithersburg, MD, [online], https://doi.org/10.6028/NIST.SP.250-102, https://tsapps.nist.gov/publication/get_pdf.cfm?pub_id=961177 (Accessed September 2, 2026)
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NIST - National Institute of Standards and Technology published this content on September 01, 2026, and is solely responsible for the information contained herein. Distributed via Public Technologies (PUBT), unedited and unaltered, on September 02, 2026 at 09:30 UTC. If you believe the information included in the content is inaccurate or outdated and requires editing or removal, please contact us at [email protected]