2007年12月5日星期三

All About Laser

Short for Light Amplification by Stimulated Emission of Radiation, LASER is a mechanical device that produces a narrow beam of light with a well-defined wavelength, capable of traveling over vast distances. The essential difference between the light emitted by a LASER and that by an incandescent light bulb is that unlike the former, the latter emits light into a large solid angle and over a wide spectrum of wavelength.

History

The groundwork for the development of LASER was completed by Albert Einstein in 1917 with the publication of his paper, "Zur Quantentheorie der Strahlung" (On the Quantum Theory of Radiation), which laid the foundation for the development of MASER (Microwave Amplification by Stimulation Emission of Radiation), the earlier version of LASER. Einstein, actually, re-derived Max Plancks Law of Radiation on the basis of the probability coefficients (Einsteins Coefficients) for the absorption, spontaneous, and stimulated emission.

After considerable developments in this field, Charles H. Townes, James P. Gordon and Herbert J. Zeiger, produced the first MASER a device that amplified microwave radiation rather than infrared radiation (which is used in LASER) in 1953. Nikolay Basov and Aleksandr Prokhorov of the erstwhile Soviet Union worked independently on MASER in 1955 and eliminated the problem of lack of continuous output in earlier version by using more than two energy levels. The development of MASER fetched Townes, Basov, and Prokhorov the Nobel Prize in Physics in 1964.

LASER began to take shape in the year 1957, when some extensive work was carried out by Townes and Arthur Leonard Schawlow (from Bell Labs) on the infrared MASER. They named the concept as an "OPTICAL MASER". Taking a cue from the subsequent patent application filed by the Bell Labs, a doctoral student from Columbia University, Gordon Gould, suggested using an open resonator, which became the basis of future lasers. The term "LASER" came to light with the publication of Goulds paper, "The LASER, Light Amplification by Stimulated Emission of Radiation" in The Ann Arbor Conference on Optical Pumping in 1959.

The invention led to a legal battle for the grant of Patent between Gordon Gould and Bell Labs that was finally settled in 1987 in favor of Gould. The first working laser was, however, made by Theodore H. Maiman in 1960 at Hughes Research Laboratories in Malibu, California. Maiman used a solid-state flashlamp-pumped synthetic ruby crystal to produce red laser light at the wavelength of 694 nanometers. Since then, LASER has been refined and adapted for several modern usages. Read more

Uses

The modern cutting-edge technologies in almost every gadget are courtesy the use of adapted LASER technology. Youll find hardly any industry that does not use laser technology to enhance the standard of living of modern human beings.wholesale pearlwholesale necklace Some of the prominent sectors that have benefited from laser use include consumer electronics, military, science and technology, information technology, medicine, law enforcement, entertainment and retail.