Total Internal Reflexion and Huyghens' Construction: the Immersion Grating

Abstract

It is not uncommonly supposed that if light falls on a dense-rare interface at more than the critical angle, no energy can penetrate into the rarer medium. Several workers¹ have shown that a certain amount of energy can penetrate a short distance, but that the disturbance is much attenuated and becomes negligible at a few wave-lengths distance from the interface. This is in accordance with Huyghens' construction² (see diagram, full circles), which gives in this case a series of secondary wavelets lying wholly within their neighbours, and hence not cutting and reinforcing at any considerable distance.