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Applied Optics

Applied Optics


  • Editor: Joseph N. Mait
  • Vol. 53, Iss. 8 — Mar. 10, 2014
  • pp: 1546–1553

Large-aperture, equal-path interferometer for precision measurements of flat transparent surfaces

Leslie L. Deck, Peter J. de Groot, and James A. Soobitsky  »View Author Affiliations

Applied Optics, Vol. 53, Issue 8, pp. 1546-1553 (2014)

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The measurement of flat optical components often presents difficulties because the presence of parallel surfaces generates multiple reflections that confuse conventional laser-based interferometers. These same parts have increasingly demanding surface finish tolerances as technologies improve over time, further complicating the metrology task. Here we describe an interferometric optical system for high-accuracy noncontact evaluation of the form and texture of precision flat surfaces based on an equal-optical-path geometry that uses extended, broadband illumination to reduce the influence of speckle noise, multiple reflections, and coherent artifacts by a factor of 10 when compared to laser-based systems. Combined with a low-distortion, fixed-focus imaging system and 4-Mpixel camera, the 100 mm aperture instrument offers surface height resolutions of 0.1 nm over lateral spatial frequencies extending from 0.01 to 10 cycles/mm. The instrument is vibration resistant for production-line testing of flat optics such as glass hard disks for the data-storage industry and flat-panel-display substrates.

© 2014 Optical Society of America

OCIS Codes
(120.3180) Instrumentation, measurement, and metrology : Interferometry
(120.3940) Instrumentation, measurement, and metrology : Metrology
(120.5060) Instrumentation, measurement, and metrology : Phase modulation
(120.6650) Instrumentation, measurement, and metrology : Surface measurements, figure
(120.7280) Instrumentation, measurement, and metrology : Vibration analysis

ToC Category:
Instrumentation, Measurement, and Metrology

Original Manuscript: December 9, 2013
Manuscript Accepted: January 15, 2014
Published: March 5, 2014

Leslie L. Deck, Peter J. de Groot, and James A. Soobitsky, "Large-aperture, equal-path interferometer for precision measurements of flat transparent surfaces," Appl. Opt. 53, 1546-1553 (2014)

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