Alight beam orbeam of light is a directional projection oflight energy radiating from alight source.Sunlight forms a light beam (asunbeam) when filtered through media such asclouds,foliage, orwindows. To artificially produce a light beam, alamp and aparabolic reflector is used in manylighting devices such asspotlights,car headlights,PAR Cans, andLED housings. Light from certain types oflaser has the smallest possiblebeam divergence.

From the side, a beam of light is only visible if part of the light is scattered by objects: tiny particles likedust, water droplets (mist,fog,rain),hail,snow, orsmoke, or larger objects such asbirds. 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 theTyndall 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 ahelmet
• Lighthouse, beam sweeping around horizontally
• Searchlight, beam directed at something

For the purpose of visibility of light beams from the side, sometimes ahaze machine orfog machine is used. The difference between the two is that the fog itself is also avisual effect.

• Laser lighting display-Laser beams are often used for visual effects, often in combination with music.
• Searchlights are often used inadvertising, for instance byautomobile 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 formoviepremieres; the waving searchlight beams are still to be seen as a design element in the logo of the20th Century Foxmovie studio.

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

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

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