Some applications of holography in fluid mechanics

The methods of wavefront reconstruction or holography discovered by Gabor and developed by Leith and Upatnieks greatly increase the amount of information which may be recorded on a single photographic plate. Holography often requires the use of slow, high resolution plates and at first sight might seem unsuitable for use in aerodynamics, in which we are usually concerned with rapidly changing phase objects. The present paper shows, however, that for some purposes the spatial frequencies required are low enough to record on fast plates. A single hologram can be produced which can be viewed at leisure by all the normal visualization methods. Some experimental results are given.