Transcript Charles Townes: The Laser - University of California, Irvine

Charles Townes
The Laser
What is a Laser?
L ight
A mplification by
S timulated
E mission of
R adiation
How does it work?
Fig 1
Fig 2
When atoms are stimulated by some energy
source, its electrons absorb the energy and
go into a higher quantum level. These
electrons then try to go back to their
original levels, releasing their energy in the
form of a photon of light. Figures 1 and 2
show this phenomenon.
A laser uses this principal within its tube, to
manipulate and control the light emission.
Since a normal flashlight uses a same
principal as that in figures 1 and 2, it is
important to note how a laser differs.
Lasers are:
Monochromatic: Having the same color of light
Coherent: The photons have same wave phase
Directional: The path of the photons are very
similar
These properties are attained through the
mirrors found in the laser
How does it work? 2
Fig 1
Fig 2
After the photons are released, they bounce around in the laser tube until their orientations cause them to
bounce between the full reflective mirror on one end and a partial reflective one. As these photons are
doing this, they are also colliding with other atoms causing their electrons to release photons which
happen to have he same wavelength (color) and phase as the the photon that impacted it, this is
known as stimulated emission. Finally, these photons which are oriented by the mirrors will go
through the partial reflected one in a intense column of light that is highly directional, and whose
photons are of the same wavelength and phase. Figure1 shows how the photons are traveling against
the mirrored surface of the tube. Figure 2 shows the photons finally leaving the tube all traveling in
the same direction.
Why are Lasers important?
•Cd players
•Barcode scanners
•Eye surgery
•Weapon guidance
•Fiber optic communications
•Laser Printers
•Laser telescopes
Are just a few of the current uses with many more being developed
every day!
Who’s idea was the Laser?
Charles Hard Townes
•Born July 28, 1915 in Greenville, S.C
•Bachelor of Science degree in physics and
Bachelor of Arts degree in Modern Languages from
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Furman University by the age of 19.
•Master of Arts degree in Physics at Duke
University
•Ph.D. degree from The California Institute of
Technology with a thesis on isotope separation
and nuclear spins
What else did he do?
M icrowave
A mplification by
S timulated
E mission of
R adiation
Before Townes developed the laser, he
worked on and developed the maser.
This device is basically the same
science as the laser except it operates
on the microwave band instead of the
optical. This device has been used in
things like the atomic clock and
electronic amplifiers for radio
telescopes. His breakthrough idea on
how to make shorter waves using
atoms not only gave rise to the
impressive laser but he is also credited
to the development of the maser.
Although the technology is similar,
each has found its own uses in
modern society.
What is he doing now?

Currently Charles Townes works as a
graduate professor at the University of
California at Berkeley, where he lives
with his wife and four daughters.

In 1998 he was celebrated at the 40th
anniversary of the laser which was
held by bell labs.

He also is an active member with
america’s youth as well its graduate
students. He has given talks with
young student audiences about his
life in an attempt to inspire and
amaze.
Timeline
1915- Born
1939 - Joins Bell Labs
1948 - Becomes an associate professor of physics at Columbia University.
1950 - Becomes a professor of physics at Columbia and executive director of the Columbia Radiation
Laboratory
1953 - Builds the first maser with J. P. Gordon and H. J. Zeiger at Columbia.
1957 - Works with A.L.Schawlow on the theory of the laser based on the principles of the maser
1959-61 - Becomes vice-president and director of research for the Institute for Defense Analysis in
Washington, D.C.
1960 - Receives with Schawlow a patent for the Laser.
1964 -- Shares the Nobel prize with A. Prokhorov and N. Basov of the Lebedev Institute in Moscow for
"fundamental work in the field of quantum electronics which has led to the construction of oscillators and
amplifiers based on the maser-laser principle.”
1966 - Becomes Institute Professor at MIT.
1967 - Becomes University Professor of Physics at the University of California at Berkeley.
1986 - Becomes University Professor of Physics, Emeritus, at the University of California at Berkeley.
Conclusion
Today, lasers are found in many aspects of our lives. We cannot
even go the buy groceries without noticing their impact on modern
society. As time goes on people will find more and more uses for
this simple yet important light making device. The next time one
see a laser in use, remember that at one time a man named Charles
H. Townes dreamed about it before it was ever created. Although,
many did not believe his inventions would have much use, even he
could not have predicted how important it has become.