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History of Lasers
LASER, an acronym for Light Amplified Stimulated by the Emission of Radiation was named after Einstein's work with stimulated emission. LASER describes the physical process which laser produces light, and Einstein first described the principal of laser action in 1917. The first practical demonstration of this principal took place in 1954 when Charles Townes reported stimulated emission of radiation in the microwave area of the electromagnetic spectrum. Thus the first instrument was called a MASER (Microwave Amplification of Stimulated Radiation). In 1958, Townes and Schawlow proposed extending the principles of maser operation to the infrared and visible light ranges of the spectrum.
Finally in 1960, Theodore Maiman stimulated a ruby crystal to produce a red laser light at a wavelength of 0.69 um. Within a year, this laser was modified for use in ophthalmology for photocoagulation of the retina. This set the stage for the development of other laser wavelengths for use in medicine.
In the last three decades, tremendous advances have been made in the medical use of lasers. Lasers today are designed to selectively target specific chromophores or targets and have become very precise instruments. This process is called selective photothermolysis.
Note: Usually, when the word "radiation" is mentioned, one tends to think of the more hazardous forms of ionizing radiation, such as x-rays and gamma rays. These types of ionizing radiation disrupt molecular structures and can increase the risk of cancer. Laser light, however, emits a non-ionizing form of radiation, which has been proven to be HARMLESS to humans. This includes pregnant women and their babies. |
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