Compact fluorescent lights (CFLs) used in the home produce 60 lumens per watt, while traditional incandescent bulbs emit a miserly 15 or so.
The compact fluorescent lights (CFLs), or "twisties", used in the home produce around 60 lumens per watt.
The number of lumens per watt (lm/W) measures a light's efficiency, while the number of dollars per lumen measures its cost.
The new white LEDs used in his street are rated at around 100 lumens per watt.
To compete with the light output of a single 60-watt incandescent bulb that emits about 800 lumens (a measure of light power as perceived by the human eye), companies such as LED Lighting Fixtures and Permlight of Southern California are designing lamps based on clusters of white LEDs that achieve a similar lumen output, but consume a fraction of the power.
That is a market worth $12 billion around the world, according to Robert Steele, an analyst with Strategies Unlimited in Mountain View, California.A light is judged by the number of lumens it throws (a lumen is a measure of brightness that accounts for the sensitivity of the human eye).
The best xenon projector lamps today typically offer around 30,000 lumens of brightness.Illuminating the same chips with lasers eliminates many of these problems.
Their uniform light is easy to work with.The first commercial laser cinema projectors contain hundreds of tiny laser diodes and offer around twice the brightness (60,000 lumens) of xenon-based projectors, while consuming only about half as much electricity.
Producing practically all their light at a wavelength near the peak sensitivity of the human eye gave them a theoretical luminous efficacy of 200 lumens per watt of electricity consumed, though their real-world performance is around two-thirds that.
That translates into a rating of 200 lumens per watt of electrical power consumed.
The quantity of light flux flowing out from a source is measured in lumens, the lumen being defined as the amount of flux radiated by a small "point" source of one candle power into a cone having a solid angle of one steradian.
