Nouveau procédé d'observation du profil et de l'éetat des surfaces par microscopie électronique; applications à...

In the first part of this paper, we show how great is the interest, from the optical point of view, of obtaining as precise as possible a determination of the shape of the surfaces. The first examples given deal with thin films; then we consider the optical gratings: here the problem is particularly important, for the true shape of the grooves, which is often different from the ideal, has a direct repercussion on the efficiency. The usual methods employed in electron microscopy do not reveal with a sufficiently good precision the topography of the surfaces. We describe the technique we have devised: it gives an image of the profile of these surfaces and enables us to know their true shape. A number of photographs obtained on thin films of CaF(2) and Se, and also on optical gratings, provide illustrations of the capabilities of this new method of observation by electron microscopy.