Visible Light and Lasers
Wavelength - 7.60 x 10 ^ -7 to 3.80
x 10 ^ -7 meters.
The
Discovery Zone
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.
How
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:
Medicine
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.
Ophthalmology
- removal of cataracts and correcting vision.
Dermatology
- removal of tattoos and skin lesions.
Dentistry -
filling cavities.
Oncology -
treatment of skin cancer.
Industry:
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.
Science:
Lasers are used:
In experimental nuclear
fission devices
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.
Consumer
goods:
Digital sound recording and video recording devices (CDs, stereophonic systems; video cassettes, videodisks). Automated checkout systems (scanners). To detect flaws in fabrics.
Dangers
When lasers aren't controlled properly by a skilled technician, the laser
can possibly do major damage to surrounding environs (ex. burns, cutting,
etc..).
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.
Precautions:
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.
Contributors: