Acoustical Holography

Only a space limitation of 115 seats prevented this First International Symposium on Acoustical Holography from having an attendance of over 250. Unfortunately, the size of the auditorium of the Douglas Advanced Research Laboratories required that attendance be by invitation only, and many deserving and interested scientists could not be present. This volume presents the proceedings of the symposium, and hopefully will help compen- sate those individuals who were unable to attend. The symposium itself consisted of sixteen formal papers. The seven- teenth, by Dr. P. Greguss, was not received in time to be read but is included in these proceedings. The presence of Professor Dennis Gabor considerably enhanced the informal sessions, which frequently became as spirited as one might expect in a new field. Dr. H. M. A. El-Sum, a consultant to the Douglas Advanced Research Laboratories and a pioneer in the field of holography, set the stage with the first paper. He provided a general introduction to the physical principles and practical methods involved in optical and acoustical holography. His paper also included a summary of various specific techniques currently used in sound holography, with the advantages, disadvantages, and limitations involved for each approach.