City of Light: The Story of Fiber Optics

36 CITY OF LIGHT
An Array of Light Pipes
A host of other inventors also dabbled with remote viewing, including Henry
C. Saint-René, who taught physics and chemistry at the agriculture school in
Crezancy, a town of about 500 people in the French district of Aisne. Most
of his ideas came from other inventors, but he proposed a novel display based
on moving tinted glass slides in front of lighted openings. Grading the tint
from top to bottom would control brightness, but Saint-René worried that
gaps between the moving slides would ruin the effect.
As he searched for a way to eliminate the gaps, he recalled the principle
of light guiding in fountains. He thought curved glass rods could collect light
from each opening and deliver it to a screen, where their other ends could
be packed together without gaps to form an image. He wrote:
A bent glass rod—its two ends cut perpendicularly to its axis—will receive
on its lower, vertical cross-section the light which it will conduct (acting
like the liquid conduit in an illuminated fountain) to the upper, horizontal
cross-section, where it is perceived by the eye. 4
Saint-René realized that each rod homogenized the light passing through
it, so he needed rods with small ends to show details. He wrote: ‘‘The whole
array gives a complete illusion of the object if the diameter of each point does
not exceed 1/3 millimeter when the viewer is at a distance of one meter from
the image.’’ 5
It is unclear whether Saint-René built anything, but he liked the idea.
However, he evidently lacked the money to file for a patent, or doubted he
could earn back his investment. Instead, in the summer of 1895 he wrote a
description of his invention and sent it in a sealed packet to the French Academy
of Sciences in Paris, which has a novel system for documenting claims
of priority. Inventors can wait years, then ask the Academy to open the packet
and publish a summary in Comptes Rendus to prove their priority. Saint-René
bided his time for over 14 years before asking the Academy to publish his
summary.
No one else shared Saint-René’s enthusiasm, even in 1910 when his idea
finally saw print. His display was the first use of a bundle of glass rods or
fibers to transmit images. Yet it remained obscure because his remote-viewing
system was impractical, one of countless schemes that came and went before
the new technology of television evolved at the hands of a new generation of
engineers and inventors. Saint-René himself vanished from the scene, and his
records probably were destroyed with those of the agriculture school when
World War I ground through the area. 6
The Birth of Television
Invention and technology changed in subtle but crucial ways in the decades
between the Paris exposition and the 1920s. Corporate research labs emerged,