ABSTRACT
Enormous improvements in Light-emitting diode (LED) lighting technologies in the past decade have led many to wonder if LED lighting will be chosen for nearly all illumination purposes. The idea is becoming increasingly popular as LEDs’ theoretical luminous efficacy, at the small-scale source level, is calculated to be about twice that of the current state-of-the-art fluorescent lamps. Luminance is defined by optical power density or luminous flux density, per unit solid angle. It is used to characterize brightness of automotive headlights, projection lights, and various computer monitor displays; when used exclusively, luminance is usually not a suitable parameter for illumination applications. LED lamps operate based on electroluminescence in semiconductor materials. LED technologies have undergone many years of industrial and academic developments in various fields including display and communications. Light sources and luminaires have been developed by engineers and scientists and used by lighting designers for illumination applications for over a century.
