In 212 BC during the siege of Syracuse, Archimedes is known to have constructed a “burning glass” to set the Roman warships afire. An array of reflective surfaces (mirror or reflective shield) was orientated toward one focal point concentrating enough energy so set the enemy boats on fire, ei a Death ray.
This experiment was reproduced by MIT’s 2.009ers students in 2009, following some previous attempts by George Louis LeClerc, Comte de Buffon, in 1747 and by a Greek scientist, Dr. Ioannis Sakkas in 1975, as described in the following links. http://web.mit.edu/2.009/www/experiments/deathray/10_ArchimedesResult.html and http://www.mlahanas.de/Greeks/Mirrors.htm
A similar approach of light concentration, can be found with the Solar energy plant such as Solar One energy plant Daggnett near Barstow, CA, USA. “Solar One uses thousands of individual sun-tracking mirrors (called heliostats) to reflect solar energy onto a central receiver located on top of a tall tower. The receiver collects the sun’s heat in a heat-transfer fluid that flows through the receiver. Solar One operated successfully from 1982 to 1988, proving that solar power towers work efficiently to produce utility-scale power from sunlight. The Solar One plant used water/steam as the heat-transfer fluid in the receiver; this presented several problems in terms of storage and continuous turbine operation. To address these problems, Solar One was upgraded to Solar Two, which operated from 1996 to 1999. Both systems had a 10 MW power capacity” http://en.wikipedia.org/wiki/The_Solar_Project
This plant was one of the earlier plant . It was followed recently by large development notably in south of Spain. http://en.wikipedia.org/wiki/List_of_solar_thermal_power_stations
The disco ball is the exact opposite of every thing presented above. It does not concentrate or focus light. On the contrary, it redirects light according to its spherical form acting similarly as convex lens, dispersing light in a multiple light projection corresponding to its facetted composition on the surrounding walls.
The movement of the ball or of the light source, enhance the dispersion by adding its own flow to the light dispersion. I have an attraction for these hypnotic light movement. This attraction is not unlike the one most of us share for the fire or the flow of water in a river …
From these few examples, we can gather a few things:
- Use of Mirror to project light into space
- Control of individual reflectors enable to focus or disperse light
- Definition of pixelated network of reflectors
All these examples use direct light, and particularly, it is required or more efficient with parallel light beam, such as Sun light.
Another family of light system are very interesting, they also use sun light ,due to their shape or their size, they are mostly working to create a diffuse soft light , enhance lighting level or control glare.
Some of these systems are developed by Siteco Light controlling system . http://www.siteco.com/en/home.html. These systems seems to be very rationally and carefully engineered, offering more natural light , more evenly distributed.
When I first saw in the book “Solar Power”, I have always found them very attractive but…May be they are too carefully engineered or too evenly distributed, as smart as these systems seem to be, I can not help being bothered as well by their evenness, their aim toward mildness, soft light.
These products are great but they reflect what natural lighting is loosing when one attempt to control it too much, its spontaneity and its intensity. A little bit of glare is acceptable in the street at end of day in the winter when the sun is very low in the horizon, why not in your office or home.
These sources of inspiration have inspired a series of project that are presented under the tittle: Light Shreder in the Project /Timescapes section of this website
Solar Power: The Evolution of Sustainable Architecture by Sophia Behling, Stefan Behling and Norman Foster (Sep 2000)