Light tubes or light pipes are physical structures used for transporting or distributing natural or artificial light for the purpose of illumination, and are examples of optical waveguides . In their application to daylighting , they are also often called tubular daylighting devices , sun pipes , sun scopes , or daylight pipes . Light pipes can be divided into two broad categories: hollow structures that contain the light with a reflective lining, and transparent solids that contain the light by total internal reflection . The principles governing the flow of lightnonimaging optics . 
Generally speaking, a light pipe or light tube may refer to:
- a tube or pipe for transport of light to another location, minimizing the loss of light;
- a transparent tube or pipe for distribution of light over icts length, Either for equidistribution along the Entire length (see aussi sulfur lamp ) or for controlled light leakage.
Both have the purpose of lighting, for example in architecture .
IR light pipes / IR light tubes
Manufacturing custom designed Infrared light pipes, Hollow waveguides and homogenizers is non-trivial. This is a highly corrosive coating of laser gold , which can be used in many corrosive atmospheres. Black laser can be applied to certain parts of light pipes to absorb IR light (see photonics ). This is done to limit IR light to only certain areas of the pipe.
While most light pipes are produced with a round cross-section, light pipes are not limited to this geometry. Square and hexagonal cross-sections are used in special applications. Hexagonal pipes tend to produce the most homogenized type of IR Light. The pipes do not need to be straight. Bends in the pipe have a little effect on efficiency.
Light tube with reflective material
Also known as “tubular skylight” or “tubular daylighting device”, this is the oldest and most widespread type of light tube used for daylighting . The concept was originally developed by the ancient Egyptians . The first commercial reflector systems were patented and marketed in the 1850s by Paul Emile Chappuis in London, using various forms of angled mirror designs. Chappuis Ltd’s reflectors were in continuous production until the factory was destroyed in 1943.  The concept was rediscovered and patented in 1986 by Solatube International of Australia. This system has been marketed for residential and commercial use. SunScope, solar pipe, light pipe, light tube and tubular skylight.
A tube 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. A light tube is not Intended for imaging (in contrast to a periscope , for example), THUS picture distortion poses no problem and are in Many Ways Encouraged due to the reduction of “directional” light.
The entrance points usually included a dome ( cupola ), qui Has the function of collecting and Reflecting sunlight as much as possible, into the tube. Many units also have directional “collectors”, “reflectors” or even Fresnel lens devices that assist in collecting additional directional light down the tube.
A set-up in which a laser cut panel is a mirror image of a vertically polarized panel the Queensland University of Technology in Brisbane.  In 2003, Veronica Garcia Hansen, Ken Yeang , and Ian Edmonds were awarded the Far East Economic Review Innovation Award for this development.  
Light transmission efficiency is greatest if the tube is short and straight. In longer, angled, flexible gold tubes, part of the light intensity is lost. To minimize losses, a high reflectivity of the tube lining is crucial; manufacturers claim reflectivities of their materials, in the visible range, of up to almost 99.5 percent.  
At the end point, spread spreads the light into the room.
To further optimize the use of solar light, a heliostat may be installed which tracks the movement of the sun, thus permitting the light of the sun. reflective elements that influence the light path. The heliostat can be set to capture moonlight at night.
Optical fibers are well Known As fiberscopes for imaging applications and as light guides for a wide-range of non-imaging applications . In the latter context, they can also be used for daylighting: a solar lighting system based on plastic optical fibers was developed at Oak Ridge National Laboratory in 2004;   The system was installed at the American Museum of Science and Energy, Tennessee, USA, in 2005,  and brought to market by Sunlight Direct.   However, this system was taken off the market in 2009.
Optical fibers are also used in the Bjork system by Parans Solar Lighting AB.   The optic fibers in this system are made of PMMA ( PolyMethylMethAcrylate ) and sheathed with Megolon, a halogen-free thermoplastic resin. A system such as this, however, is quite expensive. 
A similar system, but using optical fibers of glass, had earlier been under study in Japan. 
In the day of the day, the day-to-day operations of the day, the day-to-day running of the day, is an efficient daylighting set-up and a parabolic collector . Optical fibers intended for light transport need to propagate as much light as possible within the core; in contrast, optical fibers intended for light distribution are designed for the part of the light leak through their cladding. 
Transparent hollow light guides
A prism light guide was developed in 1981 by Lorne Whitehead, a physics professor at the University of British Columbia   and has been used in solar lighting for both transport and distribution of light.   A large solar pipe based on a 14-floor building in Washington, DC law firm in 2001,    [26 ] ]  and a similar proposal has been made for London.  A further system has been installed in Berlin. 
The 3M company developed a system based on optical lighting film  and developed the 3M light pipe,  which is a light guide designed to distribute light uniformly over its length, with a thin film incorporating microscopic prisms,  which has been marketed in connection with artificial light sources, eg sulfur lamps .
In contrast to an optical fiber which has a solid core, a prism light guide leads the light through air and is so referred to as a hollow light guide.
The project ARTHELIO,   partially funded by the European Commission, was an investigation into the years 1998 to 2000 into a system for adaptive mixing of solar and artificial light, and which includes a sulfur lamp , a heliostat , and hollow light guides for light transport and distribution.
Disney has experimented with using 3D printing . 
Fluorescence based system
In Sydney , two fluorescent polymer layers in the sunlight, particularly ultraviolet light , generating red and green light, respectively, which is guided into the interior of a building. There, the red and green light is mixed with artificial blue light to yield white light, without infrared or ultraviolet. This system, which collects light without a mobile device or a parabolic collector, is intended to transfer to any place within a building.   By capturing ultraviolet the system can be especially effective on bright but overcast days; This is because it is less visible than visible components of sunlight.
Properties and applications
Solar and hybrid lighting systems
Solar light pipes, compared to conventional and other windows, offers better heat insulation properties and more flexibility for use in the interior, but less visual contact with the external environment.
In the context of seasonal affective disorder , it may be worth considering that an additional facility of light tubes increases the amount of natural daily light exposure. It could also possibly contribute to residents ‘or employees’ well-being while avoiding over-illumination effects.
Compared to artificial lights , light tubes have the advantage of providing natural light and saving energy. The transmitted light varies over the day; should not be desired, light tubes can be combined with artificial light in a hybrid set-up.    
Some artificial light sources are at least one of the following: a spectrum of the visible range spectrum ,    and more low flicker.  Their spectrum can be made to vary dynamically as in the natural light of the day. Manufacturers et vendors of such sources may claim their natural or similar nature.    When considered as alternatives to solar light pipes, they may be more wasteful in terms of overall energy resources and costs.
They are more practical notes, and they are thus especially useful for indoor wet areas such as bathrooms and pools. From a more artistic point of view, recent developments, especially those pertaining to transparent light tubes, open new and interesting possibilities for architectural design.
Lightboxes have been used in schools,  warehouses, retail environments,   homes,  government buildings, museums, hotels  and restaurants.
They have an ideal application to security oriented situations, such as prisons , police cells and other locations. Being able to have a narrow diameter, and providing a large number of internal security grids, provides access to a secure area.
In electronic devices
Molded plastic light tubes are commonly used in the electronics industry to direct illumination from LEDs on a circuit board. These light tubes typically take on a highly complex shape that is used in the past as an optical fiber or sharp prismatic folds which reflect the angled corners. Multiple light tubes are often made from a single piece of plastic, which is very easy to use.
Light tube indicators make electronics cheaper to manufacture a small lamp in a small socket directly behind the spotlight. This often requires extensive hand-labor for installation and wiring. Light tubes permit all lights to be mounted on a single flat circuit board, but the illumination can be done.
- Anidolic lighting
- Architectural lighting design
- Active daylighting
- Passive daylighting
- Prism deck
- Green building
- Liter of Light project
- Passive house
- Passive solar building design
- Passive solar
- Prism glass
- Tubeless skylight
- Solar power , esp. the sections on solar lighting and solar design in architecture
- Zero energy building
|HAS Wikimedia Commons media related to Category: Tubular daylighting devices .|
- Light Tubes on “Potsdamer Platz” are made by Heliobus AG Switzerland 
- [ “Smart Lighting for a Smart House” (an overview over daylighting, listing aussi light pipes)] HTML
- Solar Lighting and Illumination of Buildings using Light Pipes , Florida Solar Energy Center (University of Central Florida)
- Daylighting Using Tubular Light Systems Guide (thesis)
- (in German) an overview over light guidance – PDF , HTML
- “A Study of Performance of Light Pipes Under Cloudy and Sunny Conditions in the UK”
- “Sunlight in a tube”, World Science, 2005
- A references to the installation and mounting of information
- Kneipp KG, International Lighting in Controlled Environments Workshop, TWTibbitts (editor), 1994, NASA-CP-95-3309 (with an overview on the piping of light)
- (in German) Alexander Rosemann: Hohllichtleiter für Tageslichtnutzung. Pflaum Verlag, München 2002. ISBN 3-7905-0862-4
- “A Design Tool for Predicting the Performance of Light Pipes” Jenkins et al. link title
- UK based Monodraught SunPipe (and www.sunpipe.info)
- UK based < http://www.glidevale.com/downloads/Sunscoop%20Tubular%20Rooflights.pdf > and www.glidevail.com with extensive technical and reference information
- Monodraught SunPipe – the UK’s largest and most successful seller of Light Tube products and solutions.
- Case study installing light tubes in an older residential bungalow
Other approaches to sunlight capture and transmission
- the Japanese approach of “depthscraper” : a rotating mirror planned to throw sunlight deep down into a courtyard.
- Courtyard facade with heliostats in Karl-Scharnagl-Ring Street in Munich, Germany – PDF , HTML
- Heliostats in New York City, USA
- Description, among other topics, of the 3M Solar Optical Products Daylighting Panel
- List of patent publications within the CPC class F21S11 / 00 (“Lighting devices or systems using daylight”), some of which relate to light tubes, for example:
- US patent 4761716
- US patent 6502950
- US patent 6840645
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