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Proceedings Paper

Innovative Nondestructive Techniques For Measuring The Refractive Index Of A Lens Using Laser Light
Author(s): R. S. Kasana; K. J. Rosenbruch
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Paper Abstract

Some nondestructive techniques for measuring the refractive index of a lens have been reported. The salient feature of this innovative approach is to avoid the use of two miscible liquids as commonly used in the liquid immersion method. Wavefront shearing inteferometry and the coherent speckling phenomenon have been applied for determining the focal length of the test lens immersed in different types of liquids. The reported method is quick to perform and adequate for producing good accuracy as compared with existing techniques. Our intentions and the main objectives of our efforts are to point out that the present approach is economic as well as less time-consuming, especially when the type of glass in a lens is to be identified. The preparation and the selection of the required liquids for the miscible liquid immersion technique is a time-consuming process and moreover, it needs a large number of trials to achieve the desired results. In contrast to this, the proposed method does not need two miscible liquids. A mathematical equation has been derived for calculating the lens' index which depends upon the focal lengths of the lens in different liquids and their refractive indices. It has also been deduced that the plano-convex lens and a thin lens behave in the same way and produce identical results. For N liquids there will be N(N-1)/2 ways of calculating the lens' index. Henceforth, the present technique will be termed the nondestructive nonmiscible liquid immersion technique.

Paper Details

Date Published: 26 October 1983
PDF: 7 pages
Proc. SPIE 0398, Industrial Applications of Laser Technology, (26 October 1983); doi: 10.1117/12.935392
Show Author Affiliations
R. S. Kasana, Physikalisch-Technische Bundesanstalt (Germany)
K. J. Rosenbruch, Physikalisch-Technische Bundesanstalt (Germany)

Published in SPIE Proceedings Vol. 0398:
Industrial Applications of Laser Technology
William F. Fagan, Editor(s)

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