The realization that the open atmosphere would be a very unreliable medium for the transmission of light led, soon after the invention of the laser, to consideration of the use of conduits, possibly evacuated pipes, for sending the light beams from one place to another, thereby providing a controlled atmosphere. If necessary, such conduits could be fitted with lens and mirror systems to provide beam path correction and beam path redirection. Servomechanisms could be devised to adjust the mirrors and lenses to compensate for such changes as might arise from thermal expansion or other distortions. Such systems could be made to work but undoubtedly they would be very cumbersome and if practical at all, would be so only for very heavy communications traffic routes.
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May 1976
May 01 1976
The fiber lightguide
The central component of a lightwave communication system is a fiber no thicker than a human hair, accurately formed of high‐purity glass, with low dispersion and losses as low as 1 dB per kilometer.
Physics Today 29 (5), 28–37 (1976);