Holographic Interferometry: Then and Now

In the autumn of 1964, Robert L. Powell and I discovered holographic interferometry while working at the Radar Laboratory of the University of Michigan's Institute of Science and Technology. I have worked in this field ever since, and I have watched it grow from an unexplored technology to a widespread industrial testing method, and I have contributed to these developments. In this paper, I will trace my history in this field-our discovery and my involvement in its theory and applications. I will conclude with a discussion of digital holography, which is currently replacing photographic holography for most research and industrial applications.