Light tube
[2] Manufacturing custom designed infrared light pipes, hollow waveguides and homogenizers is non-trivial.
The first commercial reflector systems were patented and marketed in the 1850s by Paul Emile Chappuis in London, utilizing various forms of angled mirror designs.
A tube lined with highly reflective material leads the light rays through a building, starting from an entrance-point located on its roof or one of its outer walls.
The entrance point usually comprises a dome (cupola), which has the function of collecting and reflecting as much sunlight as possible into the tube.
The light pipes were designed to passively transport daylighting through relatively small inlet glazing areas by reflecting sunlight to depths greater than conventional sidelight windows or skylights.
[5][6] A set-up in which a laser cut acrylic panel is arranged to redirect sunlight into a horizontally or vertically orientated mirrored pipe, combined with a light spreading system with a triangular arrangement of laser cut panels that spread the light into the room, was developed at the Queensland University of Technology in Brisbane.
A solar lighting system based on plastic optical fibers was in development at Oak Ridge National Laboratory in 2004.
[13][14] The system was installed at the American Museum of Science and Energy, Tennessee, USA, in 2005,[15] and brought to market the same year by the company Sunlight Direct.
In view of the usually small diameter of the fibers, an efficient daylighting set-up requires a parabolic collector to track the sun and concentrate its light.
[19][20] The optic fibers in this system are made of PMMA (PolyMethyl MethAcrylate) and sheathed with Megolon, a halogen-free thermoplastic resin.
[27][28] A large solar pipe based on the same principle was set up in the narrow courtyard of a 14-floor building of a Washington, D.C. law firm in 2001,[29][30][31][32][33] and a similar proposal has been made for London.
Solar light pipes, compared to conventional skylights and other windows, offer better heat insulation properties and more flexibility for use in inner rooms, but less visual contact with the external environment.
On a more practical note, light tubes do not require electric installations or insulation and are thus especially useful for indoor wet areas such as bathrooms and pools.
[citation needed] Due to the relatively small size and high light output of sun pipes, they have an ideal application to security-oriented situations, such as prisons, police cells, and other locations where restricted access is required.
Moulded plastic light tubes are commonly used in the electronics industry to direct illumination from LEDs on a circuit board to indicator symbols or buttons.
These light tubes typically take on a highly complex shape that uses either gentle curving bends as in an optic fiber or has sharp prismatic folds which reflect off the angled corners.
Light tube indicators make electronics cheaper to manufacture since the old way would be to mount a tiny lamp into a small socket directly behind the spot to be illuminated.
