The laser mechanism often uses visible light, which is a portion of the electromagnetic spectrum made up of the radiation groups called radio waves, microwaves, infrared, visible light, ultraviolet, x-rays, and gamma rays.
The electromagnetic radiation is emitted as a narrow, spatially coherent (of the same frequency, phase, and polarization), low-divergence beam, which is called laser light.
The first laser was created on May 16, 1960, just about fifty years ago, by U.S. physicist Theodore Harold 'Ted' Maiman (1927'”2007), who was working at the Hughes Research Laboratories.
Others before him laid out the theory of lasers, including Albert Einstein in 1917 when he described the theoretic foundation for the laser in his paper Zur Quantentheorie der Strahlung (On the Quantum Theory of Radiation).
Now that the laser is fifty years old, Scientific American has come out with a paper that describes the events that led up to its invention.
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The article begins: 'On August 6, 1960, Hughes Research Laboratories scientist Theodore Maiman published a study in Nature (pdf) describing his experiments with "stimulated optical radiation in ruby." (Scientific American is part of Nature Publishing Group.) With this research, he took the laser'”originally "Light Amplification by Stimulated Emission of Radiation"'”out of the realm of science fiction and created a tool that would change the world in ways few people could have conceived of at the time.'
Learn more about lasers at the American Institute of Physics (AIP) article 'Bright idea: The First Lasers.'
This article begins: 'Since ancient times, people believed that rays of light carry grand and mysterious powers. Interest in radiation redoubled around the start of the 20th century with the discovery of radio, X-rays and radioactivity. A whole spectrum of radiation opened up, with wavelengths longer or shorter than light (see sidebar). What amazing new uses might be discovered for use in medicine, communications, scientific research '” or warfare?'
We might not think too much about lasers in our daily lives, but our daily lives are filled with applications that owe their existence to lasers. When you go to the supermarket or any retail store your items are scanned with a barcode scanner that uses a laser. When you play your CDs or DVDs you use a laserdisc player.
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In manufacturing, welding, cutting, and other processes use lasers to make products, and to measure and analyze their safety and reliability.
We defend our country with missiles that use lasers to guide them, and we use instruments that use lasers to spy on our enemies and to find out where we are with respect to an enemy target.
Our police and law enforcement agencies use lasers to make sure we identify criminals through fingerprint detection techniques and to assure we can solve crimes involving forensic identification.
Other uses for lasers are found at "How Lasers Work."
The laser is an amazing invention that makes our world a lot more simple, easy, and fun. And, it makes a world that is much safer, too.
As a note: U.S. physicist Gordon Gould (1920'”2005) is also sometimes given credit for the invention of the laser in 1957 (three years before Dr. Maiman). Unfortunately, he did not file a patent for his invention, while Maiman did. He ended up trying to convince the U.S. Patent and Trademark Office that he had the patient rights for the laser and other related technologies. He is generally claimed to be the first person to use the acronym LASER.
For more information on Dr. Gould, please read the article 'Gordon Gould - History of the Laser.'