Geometric area measurements of circular apertures for radiometry at NIST

Joel Fowler, Maritoni Litorja
2003 Metrologia  
NIST has established a geometric aperture-area measurement facility for circular apertures. The instrument consists of an interferometrically controlled XY translation stage for high-accuracy positioning and a video microscope for detection of the edge of the aperture. Least-squares fitting of the edge points located along the aperture's inner circumference to the equation of a circle is used to determine the geometric area. In this paper we describe the measurement method, based on the work
more » ... ased on the work started and described by Fowler et al (1998 Metrologia 35 497-500). Analysis and estimation of various contributions to the overall measurement uncertainty, including the effects of diffraction and partial coherence of light on the edge location, are also discussed.
doi:10.1088/0026-1394/40/1/303 fatcat:j7r7op3oj5gcjcdizzhginf55a