City of Light: The Story of Fiber Optics

99 PERCENT PERSPIRATION 71
Hirschowitz tested the first commercial gastroscope in 1960 at the University
of Alabama Hospital in Birmingham, where he had moved after leaving
Michigan. Other doctors quickly adopted them. 51 They were a dramatic
advance, the first instruments that allowed doctors to see inside the stomach
with little risk to the patient. Only a handful of specialists mastered the delicate
techniques of using semirigid lensed gastroscopes; many more physicians
could use thin, flexible fiberscopes. By the late 1960s, they almost totally
replaced lensed gastroscopes, quickly becoming important new tools in treating
many internal conditions. Only recently have tiny electronic cameras
begun to replace flexible fiber bundles.
Fiber Optics Brighten Military Images
Shortly before the CIA gave up on image scramblers, an old Berkeley friend
at the MIT Lincoln Laboratory near Boston asked Hicks for help. Bill Gardner
was working on image intensifiers, tubes that sense weak visible or infrared
light and turn it into brighter images, so soldiers and pilots can see better.
The Pentagon thought that using one tube to amplify the output of another
should yield even brighter images. However, the output faces of the tubes
were curved so sharply that ordinary optics couldn’t focus light from one tube
onto another. Gardner asked Hicks if fiber optics could do the job. 52
The tube’s input was a flat screen, which released electrons when light hit
it. An electric field inside the tube accelerated the electrons so that they hit
a phosphor screen like a black-and-white television, producing a brighter image.
That screen had to be curved outward to collect electrons in the right
places to replicate the image accurately. Standard optics could not focus light
from the curved phosphor screen onto the flat input face of another tube
without losing light and distorting the picture.
Gardner and Hicks decided the solution was to mount a short, fat bundle
of parallel fibers between the tubes. They ground out one side so that it fit
perfectly over the curved end of the tube. The other end was flat. The array
of short fiber segments, called a ‘‘faceplate,’’ carried light straight from the
curved face to the corresponding point on the flat face of the next tube. 53 The
idea was a logical extension of Baird’s 1927 television patent. (A mineral
known as ulexite forms similar structures naturally—see box, page 74.)
It was also a natural application for the fused multifiber technology American
Optical had started developing for image scramblers. Faceplates sealed
the end of the tube, so they had to be rigid and vacuum tight. The early tubes
had screens a couple of inches across, and the faceplates were disks, which
could be sliced from a fused bundle of multifibers like a salami—or millefiori
paperweights. 54
American Optical charged ahead, fueled by ample Pentagon funding and
its new fiber-optic skills. AO engineers mastered the practical techniques of
making large bundles, drawing them into large multifibers, and slicing the