Abstract
Holography provides a method of storing the information (size and relative position) of a dynamic three-dimensional distribution of particles so that a stationary image can be produced for detailed study. The depth of field is considerably better than normal image formation. The major technique involves forming an in-line Fraunhofer hologram; this hologram is the interference pattern formed between the far field diffraction pattern of the particles and an in-line background. Off-axis holography can also be used. The basic principles of these methods are described, and practical limitations and advantages discussed. Application of the methods to fog, mist, sprays, rocket engine studies, two phase flow, bubble chamber photography, electron beam holography, etc. are reviewed.