Light beam

 ( Light ) 

A light beam or beam of light is a directional projection of light energy radiating from a light source. Sunlight forms a light beam (a sunbeam) when filtered through media such as , foliage, or . To artificially produce a light beam, a lamp and a parabolic reflector is used in many lighting devices such as spotlights, headlamp, PAR Cans, and LED housings. Light from certain types of laser has the smallest possible beam divergence.

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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 . 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.

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Visibility from the side as side effect

• Flashlight (UK 'Torch'), 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

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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 film ; 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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Other applications

• Optical communication
• Infrared Data Association (IrDA) standards
• Infrared remote control
• Security alarms
• Fibre optics
• Laser pointer
• Laser sight
• List of applications for lasers

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See also

• Beam diameter
• Collimated beam
• Crepuscular rays
• Light pillar, atmospheric optical phenomena
• Pencil beam
• Ray (optics)
• Relativistic beaming

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External links

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

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