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Re: Laser question



On Fri, 10 Dec 1999 05:05:09 -0600 Digby Willard
<dwillard@MAIL.CENTRAL.STPAUL.K12.MN.US> writes:
One of my students just took apart a He-Ne laser and found that the
tube emits at both ends, one of which is covered. Is this supposed to
happen?
Digby Willard

The typical HeNe laser tube has dielectric mirrors at both ends. One of
them
(at the front) usually reflects about 99% of the light and transmits 1%
which
forms the outgoing beam. The mirror at the other end refelcts about
99.9%
of the light back into the tube and transmits a very weak beam.

Some of the HeNe lasers have openings at both ends so a beam is emitted
at each end for alignment of pipes, ceilings etc. This information and
other
interesting information about laser operation can be obtained from
the Metrologic laser teaching supplement. To obtain a free copy, send an
e-mail to A.Swan@metrologic.com

Herb Gottlieb from New York City
(Where not all of our students are as observant as yours)