Interference rings are observed when a ruby maser beam falls on a photographic plate placed normal to the beam, without the use of any lenses. The rings produced by several different ruby rods at distances of 40–700 cm from the ruby rods have been studied. Measurements of the ring radii along with other observations are in good agreement with a simple theory which predicts such ring fringes. The interpretation given here is that these fringes arise from the interference of “off-axis” rays produced by scattering of light in the axial modes at the surfaces or within the ruby rod.
Optical Society of America
Applied Optics2, no. 8: 811–815.
The authors were affiliated with the National Research Council of Canada, Division of Pure Physics and the Radio and Electrical Engineering Division when they authored this article.