- Light beam
A light beam or beam of light is a narrow
projectionof lightenergy radiating from a source into a beam. Sunlightis 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 reflectoris used in many lightingdevices such as spotlights, car headlights, PAR Cans and LED housings.
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 machineor fog machineis used. The difference between the two is that the fog itself is also a visual effect.
Laser lighting display- Laserbeams are often used for visual effects, often in combination with music.
*Searchlights are often used in
advertising, for instance by automobiledealers; 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.
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