91av

Lasers making light work

By Jeff Hecht

17 June 1989

91av. Science news and long reads from expert journalists, covering developments in science, technology, health and the environment on the website and the magazine.
Incoherent and coherent light
Absorption of light in lasers
A semi-conductor junction laser

Nearly 30 years afters its birth, the laser still seems exotic. Its most
dramatic uses remain in the laboratory or, in the case of “Star Wars” laser
weapons, in the realm of science fiction. Yet like satellites, lasers have
become part of our lives

LASERS GIVE out a special kind of light called coherent light. You can think
of coherent light as an army of soldiers, marching in step, in the same
direction, and wearing the same uniform. Ordinary light, though, is
incoherent. Like a tightly controlled army, laser light can do things that
less-organised light – or people –…

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