Maro Publications

Lasers

Notes

From 01/24/2015 through 7/3/2012

Maro Topics

Comments

Patent Abstracts

Patent Titles

Laser Applications

Laser Sintering

Laser Ultrasonics

Radiation

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Notes

A laser is a device that emits light (electromagnetic radiation) through a process of optical amplification based on the stimulated emission of photons.  The term "laser" originated as an acronym for Light Amplification by Stimulated Emission of Radiation. The emitted laser light is notable for its high degree of spatial and temporal coherence, unattainable using other technologies.

Spatial coherence typically is expressed through the output being a narrow beam which is diffraction-limited, often a so-called "pencil beam." Laser beams can be focused to very tiny spots, achieving a very high irradiance.  Or they can be launched into a beam of very low divergence in order to concentrate their power at a large distance.

Temporal (or longitudinal) coherence implies a polarized wave at a single frequency whose phase is correlated over a relatively large distance (the coherence length) along the beam.  A beam produced by a thermal or other incoherent light source has an instantaneous amplitude and phase which vary randomly with respect to time and position, and thus a very short coherence length.

Most so-called "single wavelength" lasers actually produce radiation in several modes having slightly different frequencies (wavelengths), often not in a single polarization. And although temporal coherence implies monochromaticity, there are even lasers that emit a broad spectrum of light, or emit different wavelengths of light simultaneously.  There are some lasers which are not single spatial mode and consequently their light beams diverge more than required by the diffraction limit.  However all such devices are classified as "lasers" based on their method of producing that light: stimulated emission.  Lasers are employed in applications where light of the required spatial or temporal coherence could not be produced using simpler technologies.

(Wikipedia, Lasers, 7/3/2012)

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Interested!!
Bookmark this page to follow future developments!.
(RDC 6/5/2012)

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Roger D. Corneliussen
Editor
www.maropolymeronline.com

Maro Polymer Links
Tel: 610 363 9920
Fax: 610 363 9921
E-Mail: cornelrd@bee.net  

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Copyright 2012 by Roger D. Corneliussen.
No part of this transmission is to be duplicated in any manner or forwarded by electronic mail without the express written permission of Roger D. Corneliussen
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* Date of latest addition; date of first entry is 7/3/2012.