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Applied Optics

Applied Optics


  • Vol. 43, Iss. 10 — Apr. 1, 2004
  • pp: 2023–2028

Effects of source shape on the numerical aperture factor with a geometrical-optics model

Der-Shen Wan, Joanna Schmit, and Erik Novak  »View Author Affiliations

Applied Optics, Vol. 43, Issue 10, pp. 2023-2028 (2004)

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We study the effects of an extended light source on the calibration of an interference microscope, also referred to as an optical profiler. Theoretical and experimental numerical aperture (NA) factors for circular and linear light sources along with collimated laser illumination demonstrate that the shape of the light source or effective aperture cone is critical for a correct NA factor calculation. In practice, more-accurate results for the NA factor are obtained when a linear approximation to the filament light source shape is used in a geometric model. We show that previously measured and derived NA factors show some discrepancies because a circular rather than linear approximation to the filament source was used in the modeling.

© 2004 Optical Society of America

OCIS Codes
(120.2830) Instrumentation, measurement, and metrology : Height measurements
(120.5050) Instrumentation, measurement, and metrology : Phase measurement

Original Manuscript: October 3, 2003
Revised Manuscript: January 20, 2004
Published: April 1, 2004

Der-Shen Wan, Joanna Schmit, and Erik Novak, "Effects of source shape on the numerical aperture factor with a geometrical-optics model," Appl. Opt. 43, 2023-2028 (2004)

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  5. Measurement was performed with a Wyko NT 3300 optical profiler (Veeco Instruments, Tucson, Ariz.).
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