Visible Light and Lasers
Wavelength - 7.60 x 10 ^ -7 to 3.80
x 10 ^ -7 meters.
Who discovered Lasers?
Albert Einstein (1917) proposed the mechanism of stimulated emission - the
principle of laser's action. Einstein's spontaneous emission discovery, a
process that occurs in atoms, led him to develop the idea of stimulator led
emission. In the 1950's, researchers proposed designs for a device that would
stimulate emission to amplify light. The first laser was built by Theodore H. Maiman In 1960.
lasers are produced
The man-made process involves the following:
An energy source
An active medium
An optical cavity.
The active medium absorbs energy from the source, stores it, and releases
it as light. Some of this light triggers other atoms to release their energy,
thus more light is added to the triggering light. Mirrors at the end of the
optical cavity reflect the light back into the active medium, and the process
begins again, making the light grow stronger and causing part of it to emerge
as a narrow beam - a laser. In order to increase light emission there must be
more atoms in the excited state than the ground state; this is called
population inversion. This state does not occur under normal conditions.
Therefore, this process must be assisted by man-made technology, not nature.
How lasers are used:
Lasers are used in Microsurgical
procedures such as making small, precise incisions, liver operations, and
capillary surgery, causing little loss of blood. Lasers are also used to drill
eyes in surgical needles.
- removal of cataracts and correcting vision.
- removal of tattoos and skin lesions.
treatment of skin cancer.
Lasers are used for cutting and welding
procedures - mostly where small parts are involved. Laser beams weld wires onto
microcircuits and repair damaged wires inside glass tubes. By aligning heavy
machinery equipment, a laser interferometer can control the operations of
machinery. Lasers are able to cut teeth in saws. Lasers are also used to create
perfect right angles in place of the traditional chalk-line or T-square.
Lasers are used:
In experimental nuclear
To create holograms
To create super hot gases called plasmas
To monitor shifts in the Earth.
In the Hubble Telescope to overcome the effects of atmospheric turbulence.
Digital sound recording and video recording
devices (CDs, stereophonic systems; video cassettes, videodisks). Automated
checkout systems (scanners). To detect flaws in fabrics.
When lasers aren't controlled properly by a skilled technician, the laser
can possibly do major damage to surrounding environs (ex. burns, cutting,
Lasers using gases can, if not handled correctly, develop leaks, allowing
poisonous vapors to escape into the environment.
Also, very powerful, high concentration lasers can burn or cut the skin.
Lasers can also prove to create more problems in surgical procedures than they
correct. In medical applications, when lasers are used to treat skin cancers,
the laser beam impact may push some live cancer cells deeper into the patients
body, allowing the cancer cells to multiply, and spread further.
Scientific goggles are worn to protect the eyes from harmful light
emissions. Protective gear is worn to prevent accidents to the technician
(gloves, etc.....) The environment may be affected by the gases that are used
to produce the laser because they involve dangerous components, and must be
monitored continually for vapor leaks.
One precaution we take in our environment to protect ourselves from the
dangers of visible light is to safeguard our eyes from direct sunlight, or any
form of bright light. Through the use of sunglasses and various other light
reducing devices, we may greatly reduce damages to the sensitive parts of the
inner eye, especially the retina.
Interesting information not included above:
Laser Centerline Localize is used to help Navy pilots as far as 11 miles
out to sea, land safely on an aircraft carriers in the middle of the night. In
microsurgery, lasers are used in the removal of the heads of human sperm.
(Laser scissors/Laser Tweezers)
The Doppler effect for light.
When a source of light waves is moving with respect to an observer, it
changes the frequency that is observed. When the source of the wave is moving
toward the observer, the observed frequency increases. When the source moves
away from the observer, a lower frequency will be observed.
"Optical Refrigeration Proves Really
Cool"-Science News Oct. 14,1995
Richard I. Epstein, an astrophysicist at Los Almos, New Mexico National
Laboratory and some colleges have developed the "Optical
Refrigerator", using lasers. Since heat rises because of atomic motion, a
carefully turned laser will cool an object to give off energy as fluorescent
light. In 1829, this idea of laser cooling started, but scientists couldn't get
it to work until recently. Now, there are compact, solid state lasers and
fiber-optic materials used.