Light beam

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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 nursery decoration

Flashlight - beam directed by hand stocking holders

Headlight - forward beam; the lamp is mounted in a vehicle, or on the forehead of a person, e.g. built into a helmet advent wreath

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 beams used for visual effects during musical performance.

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

Ray (optics)

Pencil beam

Crepuscular rays

Laser

Lighthouse

Sunbeam

References

^ Guinness world record for harbour show (21 Nov 2005)

External links

A short video showing how you can put sound on a light beam and transmit it by the Vega Science Trust

Categories: Lighting | Geometrical opticsHidden categories: Articles lacking sources from August 2007 | All articles lacking sources