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Optical Engineering

Reflection Of Laser Radiation From Transparent Media (N >1) With A Diffusely Reflecting Substrate
Author(s): D. C. Look, Jr.; H. F. Nelson
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Paper Abstract

A small dark ring is formed when laser radiation is incident normally on a thin slab of transparent material that has an index of refraction greater than one, a smooth, specularly reflecting front surface, and a white diffusely reflecting substrate. The dark ring, which is located on the substrate, increases in size as the thickness of the transparent medium increases. It is formed when (1) the ratio of transparent medium thickness to diameter and (2) the ratio of laser beam diameter to transparent medium diameter are small. Since the radius of the dark ring is a function of the transparent medium thickness (as well as the index of refraction), the problem is two-dimensional. Experimental data are presented for the backscattered radiation in the normal direction as a function of radial distance from the incident laser beam. A geometric optics development is used to explain (1) the ring formation and (2) the effect of finite-sized detection apertures. Comparisons with the experimental measurements are used to verify the theoretical analysis.

Paper Details

Date Published: 1 January 1986
PDF: 7 pages
Opt. Eng. 25(1) 251173 doi: 10.1117/12.7973796
Published in: Optical Engineering Volume 25, Issue 1
Show Author Affiliations
D. C. Look, Jr., University of Missouri-Rolla (United States)
H. F. Nelson, University of Missouri-Rolla (United States)

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