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Optical Engineering

Interferometric but nonspectroscopic technique for measuring the thickness of a transparent plate
Author(s): John C. Brasunas; G. Mark Cushman
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Paper Abstract

A simple technique is presented for estimating the thickness of a transparent plate. Using a laser source and detector, the transmitted light is measured as a function of angle of incidence. With prior knowledge of the refractive index of the plate at the laser wavelength, the observed fringes can be processed to estimate the plate thickness. The technique works with a modest degree of wedging, as long as fringes are discernible. Formal estimates of the error budget indicate the accuracy of this method is approximately 1 μm. If fringes are measured versus both angle and wavelength, it should be possible to estimate both thickness and refractive index.

Paper Details

Date Published: 1 July 1995
PDF: 5 pages
Opt. Eng. 34(7) doi: 10.1117/12.206585
Published in: Optical Engineering Volume 34, Issue 7
Show Author Affiliations
John C. Brasunas, NASA Goddard Space Flight Ctr. (United States)
G. Mark Cushman, Hughes-STX (United States)

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