A light beam or beam of light is a narrow projection of light energy radiating from a source into a beam. Sunlight is a natural example of a light beam when filtered through various mediums (clouds, foliage, windows, etc). To artificially produce a light beam, a lamp and a parabolic reflector is used in many lighting devices such as spotlights, car headlights, PAR Cans and LED housings. Light from certain types of laser has the smallest possible beam divergence, thus producing the most parallel light beams possible.
Contents |
Visible light beams
From the side, a beam of light is only visible if part of the light is scattered by objects: tiny particles like dust, water droplets (mist, fog, rain), hail, snow, or smoke, or larger objects such as birds. If there are many objects in the light path, then it appears as a continuous beam, but if there are only a few objects, then the light is visible as a few individual bright points. In any case, this scattering of light from a beam, and the resultant visibility of a light beam from the side, is known as the Tyndall effect.
Visibility from the side as side-effect
- Flashlight - beam directed by hand
- Headlight - forward beam; the lamp is mounted in a vehicle, or on the forehead of a person, e.g. built into a helmet
- Lighthouse - beam sweeping around horizontally
- Searchlight - beam directed at something
Visibility from the side as purpose
For the purpose of visibility of light beams from the side, sometimes a haze machine or fog machine is used. The difference between the two is that the fog itself is also a visual effect.
- Laser lighting display- Laser beams are often used for visual effects, often in combination with music.
- Searchlights are often used in advertising, for instance by automobile dealers; the beam of light is visible over a large area, and (at least in theory) interested persons can find the dealer or store by following the beam to its source. This also used to be done for movie premieres; the waving searchlight beams are still to be seen as a design element in the logo of the 20th Century Fox movie studio.
See also
References
External links
Open source encyclopedia content modification information:
This page was last modified on 21 February 2010 at 17:24.
Authorship and Review
Open source encyclopedia content provided here is not reviewed directly by PediaView.com. Content is authored by an open community of volunteers and is not produced by or in any way affiliated with PediaView.com.
Usage Guidelines
This article is licensed under the GNU Free Documentation License. It uses material from the Wikipedia article on "Light beam", which is available in its original form here:
http://en.wikipedia.org/w/index.php?title=Light_beam
All Wikipedia text is available under the terms of the GNU Free Documentation License. Wikipedia® itself is a registered trademark of the Wikimedia Foundation, Inc.