Holography as a New Tool for Investigating Photochemical Reactions in the Solid State

Abstract

Abstract In general holography1 is known as a technique to produce a threedimensional picture which can be stored in a twodimensional photographic film. To do this an object wave, carrying all information about the object in its intensity and phase distribution, is overlapped with a reference wave at the surface of a photographic film (see Figure 1a). Since both waves are mutually coherent in space and time they produce an interference pattern. This interference pattern is impressed photochemically into the film. The photochemically stored interference pattern is called the hologram. If such a hologram is illuminated by the reference wave only (see Figure 1b) the stored interference fringes diffract part of the reference wave in such a way that an exact reconstruction of the object wave occurs. Since not only the intensity but also the phase of the object wave are reconstructed correctly a three-dimensional picture is reproduced. During the past decade 2 the applications of holography have increased strongly including for example holographic interferometry, optical memories and holographic optical elements. In this article a new application will be described which uses the connection between the growth of a hologram and the photochemical impressed interference pattern to detect the photochemistry going on in the holographic film. The techniques3-8 developed so far will be described shortly.