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Technology and Culture 46.1 (2005) 77-103
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Holography and the Emergence of Technical Communities
Sean F. Johnston
In November 1964, a bemused magazine journalist recorded this scene in a crowded Boston hotel suite:
A few dozen normally sedate scientists and engineers were playing with a toy locomotive, a toy train-conductor and other such items. The train wasn't really there at all. But if you stood in exactly the right place and looked into a piece of equipment you would have seen it, real as life. The toys had been "reconstructed" by a technique that looks simple, yet is one of the most sophisticated developments in modern science. The "reconstruction" was done with a gas laser made by Perkin-Elmer Corp., and a "hologram," a special photographic plate made by researchers at the University of Michigan.1
The hotel gathering mirrored the surprise of optical specialists at a remarkable paper given at a conference in Washington, D.C., eight months earlier. As the paper's coauthor, Emmett Leith, recalled of that first demonstration: "There was a big exodus of people from the meeting room. . . . We went up and found a line that stretched down the hall as far as you could see. They would look at the hologram, and even though most of them were optical scientists, they did not understand what was going on. They assumed it was [End Page 77] a projection system done with mirrors, and that the little toy train was hidden somewhere."2
The members of the expert audiences at these 1964 meetings struggled to fit this stunning new type of image into their understanding of optics. Their varying success in doing so illustrated a gradual process of intellectual adaptation and cultural mutation. This extraordinary new technology, sprouting in a quiet disciplinary backwater, was taken up by existing technical communities and gave rise to new ones. Technology and technical communities grew together, mutually shaping and stabilizing each other.
During its first fifty years, the itinerant subject latterly known as holography was repeatedly reconceptualized in new intellectual and geographical territories. Conceived in 1947 by Dennis Gabor, an émigré Hungarian research engineer at British Thomson-Houston in England, as a means of improving image quality in electron microscopy, it was variously dubbed "holoscopy," "wave front reconstruction," and "diffraction microscopy," as a handful of researchers pursued it over the ensuing decade.3 As an "improved" form of microscopy it was eventually judged to have severe limitations: electron microscopes proved too unstable to yield the necessarily long photographic exposures, and the optical technique itself was marred by an undesired "conjugate" image. By 1958 research had ceased, and the sole industrial laboratory pursuing the technique had categorized it as a white elephant.4 Holography was revitalized unexpectedly in the early 1960s by electrical engineers and physicists combining findings in information theory and coherent optics with newly available lasers.5
The novel principle behind the invention of holography is a two-step imaging process. First, an interference pattern (the "hologram") is recorded by superposing two beams of light, one reflected from the subject and the other traveling directly from the light source. The light must have a high degree of coherence, that is, a well-defined wavelength and stability of phase. Since 1963, holograms have almost exclusively been recorded using lasers, but other light sources, such as filtered mercury lamps, have adequate coherence for some purposes. The interference pattern of the hologram [End Page 78] is recorded on a photosensitive material such as high-resolution photographic film. Because these materials are very insensitive to light and must record patterns finer than several thousand lines per millimeter, the long exposure normally restricts the technique to inanimate objects. Nevertheless, methods of synthesizing holograms from cinema film allow images of outdoor scenes and living subjects to be reconstructed in three dimensions and with limited animation.
The second step of the imaging process is the reconstruction of the wave front of light by illuminating the hologram with a suitable light source. Until the end of the 1960s, most holograms had...