City of Light: The Story of Fiber Optics

74 CITY OF LIGHT
Some applications were quite specific. Lured to IBM by a handsome salary
offer after earning America’s first doctorate in fiber optics from Rochester, 66
Bob Potter put fibers to work reading the punched paper cards that symbolized
computers in the 1960s. Early card readers used an array of 12 small and
short-lived ‘‘grain of wheat’’ bulbs, one to illuminate each row of holes in the
moving card. Potter replaced them with a fiber bundle that collected light
from one long-lived bulb and split into 12 smaller bundles, one going to each
hole. Before it became the first fiber-optic system to march into obsolescence,
it earned American Optical some money on its fiber-optic investment.
Flexible bundles soon spread beyond medicine. American Optical developed
bundles 9 and 15 feet long for NASA testing of the Saturn boosters used in
the Apollo program. An American security agency investigated flexible bundles
for surveillance. 67
Ulexite: A natural fiber bundle
Nature makes its own bundles of optical fibers: a mineral called ulexite. It’s a
complex boron compound formed where mineral-rich lakes evaporate, found in
Boron, California. As the mineral crystallizes, long, thin crystals grow parallel to
each other and eventually merge into a solid block. Slice the block perpendicular
to the filaments and polish the faces smooth, and it acts like a fiber-optic
faceplate. Toy and rock shops sometimes sell it as ‘‘television stone.’’
Although ulexite was discovered around 1850, nobody took a close look at
its optical properties until roughly a century later. It inspired no fiber-optic
pioneers; some had never heard of it until I mentioned it. Only in 1963, several
years after the faceplate was invented, did Bob Potter recognize ulexite as a
natural fiber bundle.
Parallel filamentary crystals in ulexite guide light along their lengths like fibers in
a faceplate. (Courtesy Dan Garlick, from G. Donald Garlick and W. Barclay
Kamp, ‘‘The strange optical properties of ulexite,’’ Journal of Geological
Education 39, pp. 398–402, 1991)