About cookies on this site Our websites require some cookies to function properly (required). In addition, other cookies may be used with your consent to analyze site usage, improve the user experience and for advertising. For more information, please review your options. By visiting our website, you agree to our processing of information as described in IBM’sprivacy statement. To provide a smooth navigation, your cookie preferences will be shared across the IBM web domains listed here.
Publication
Applied Optics
Paper
Scanning differential interferometer to measure index heterogeneity
Abstract
The index heterogeneity of rectangular glass samples is measured to a repeatability of 2 x 10-8 by a scanning differential interferometer. The noise-limited instrument resolution is 2 nm of optical path length. The surface figure is decoupled from bulk inhomogeneity by a thin film of index-matching liquid, which is located by surface tension between the interferometer cavity and the test sample. An algorithm based on Poisson’s equation reconstructs the integrated optical path length profile from data in differential form with a minimal integration of noise. © 1992 Optical Society of America.