Rings observed on a transparent plate coated with a diffusing layer.
We have observed a series of regularly spaced concentric rings on a transparent plate with parallel faces coated with a thin layer of diffusing material on which a beam of light was focused. This is not due to the phenomenon of interference or diffraction but is caused simply by a visualization on the diffusing layer of the light intensity resulting from multiple total or partial reflections on the two faces. We obtained good agreement between experimental measurements and a mathematical model. We followed two approaches in the calculations: one using a closed expression, and the other a simulation by the Monte Carlo method. Both methods are based on Fresnel's formula for the transmission of light.
Bourdinaud
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Blumenfeld
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