9A9 - Pulsed laser holograms

The limited coherence of most pulsed lasers is the principle difficulty in making pulsed holograms. This paper describes techniques used for the production of quality holograms of back lighted subjects, using ordinary pulsed lasers. The arrangements used achieve a temporal and spatial matching of the scene and reference beams to the degree required by the laser coherence cell. Techniques are described which prevent the destruction of the spatial match when using a diffusing screen. The use of lenses to permit the recording of large subjects on small holograms with limited pulsed energy is described. The limitations on subject motion are described. Experimental examples of the techniques are illustrated by holographic recordings of bullets in flight. The technique of double exposure holographic interferometry is also illustrated.