Aperture area measurement facility

Metadata Updated: March 8, 2017

NIST has established an absolute aperture area measurement facility for circular and near-circular apertures use in radiometric instruments. The facility consists of the aperture area instrument, which is housed in the Advanced Measurement Laboratory (AML). The instrument is based on non-contact, video microscopy. Apertures with nominal diameters ranging from 0.5 mm to 50 mm, with both knife and flat edges, can be measured. The measurement is made by locating the edge points along the internal aperture circumference and using fitting routines to determine the geometric aperture area.The instrument consists of a broadband light source (white light with green pass filter), a Kohler illuminator, an air bearing-supported open-frame XY stage with a heterodyne laser interferometer feedback system for XY-axis positioning, a Z-axis translation stage carrying a microscope with long working distance objectives, a digital CCD camera and a control computer. The optical and mechanical components are supported on a granite base and vertical bridge structure mounted on a vibration-isolated optical table. A 10-cm diameter circular opening at the center of the base allows the Kohler illuminator to illuminate the sample from below. The base carries the XY stage and the interferometer and the bridge structure carries the Z-axis stage.Characterization of the whole system and all its components were initially performed and only minor periodic recalibration and alignment are necessary.Below is a table of the sources of uncertainty in area measurements in this facility. Two examples, a 5 mm and 50 mm diameter aperture, and the typical values of each component encountered in measuring these aperture sizes, are shown.Uncertainties2.5 mm radius25 mm radiusSourceQuantityu(R)u(R)/Ru(A)/Au(R)u(R)/Ru(A)/ARandom + form50 nm5.00E-52.00E-54.00E-55.00E-52.00E-64.00E-6Sys. stage2.6E-6*2R1.30E-55.20E-61.04E-51.30E-45.20E-61.04E-5Sys. imaging4 nm4.00E-61.60E-63.20E-64.00E-61.60E-73.20E-7Thermal change0.310E-6R7.50E-63.00E-66.00E-67.50E-53.00E-66.00E-6Geometry[HTML_REMOVED]=0.33.42E-51.37E-52.74E-53.43E-41.37E-52.74E-5TOTAL (k=1)6.69E-52.67E-55.35E-54.40E-41.76E-53.52E-5TOTAL (k=2)1.34E-45.35E-51.07E-48.79E-43.52E-57.03E-5Specifications / Capabilities:This aperture facility can routinely measure circular apertures with diameters from 0.5 mm to 50 mm. It may be able to accommodate up to 80 mm diameter apertures, which is close to the limits of linear stage travel. Non-circular apertures can be also measured but may require additional research work. The facility is also equipped with a touch probe stylus for apertures with a long vertical edge (land).Scientific Opportunities / Applications:This vision-based dimensional metrology system is flexible enough to look at dimensional metrology of irregularly-shaped system provided optical contrast is adequate.

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Public: This dataset is intended for public access and use. License: No license information was provided. If this work was prepared by an officer or employee of the United States government as part of that person's official duties it is considered a U.S. Government Work.

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Dates

Metadata Created Date March 8, 2017
Metadata Updated Date March 8, 2017

Metadata Source

Harvested from Federal Laboratory Consortium Data.json

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Resource Type Dataset
Metadata Created Date March 8, 2017
Metadata Updated Date March 8, 2017
Publisher Federal Laboratory Consortium
Unique Identifier C3978643-DFEF-4399-ABAC-70DC845DEA6D
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Maritoni Litorja
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Harvest Source Title Federal Laboratory Consortium Data.json
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