If well designed, an LED circuit can approach of 80% efficiency, which means it will convert 80% of the electric energy to light. LEDs are used in general at automotive, aviation lighting & traffic signal.

As more powerful LEDs and LED illumination systems become available, developers of both lighting and illumination devices are taking advantage of them to develop novel products. In the design of its next-generation hand-held DataMan 7500 readers, for example, Cognex incorporated a custom LED design that offers on-axis, off-axis, and dome illumination. "Direct front lighting, however, can produce an image with excessive contrast. In such cases, important object features could be hidden by dark or bright areas in the image. In these cases, darkfield illumination is best used to illuminate the contour of the mark, enhancing embossed or engraved surface features."

While the luminous efficiency of white LEDs is currently 40 lm/W, the target, according to the Optoelectronics Industry Association, is to reach 150 lm/W by 2012. One of the two approaches to increasing the light output from LED lighting sources is to produce single-power LED packages that can be attached to a printed-circuit board in tight clusters.

The operational life of current white LED lamps is 100,000 hours. This is 11 years of continuous operation, or 22 years of 50% operation. The long operational life of a led lamp is a stark contrast to the average life of an incandescent bulb, which is approximately 5000 hours. The main limitation to the adoption of white LED lighting as a lighting standard is the current high cost of led bulbs. If the lighting device needs to be embedded into a very inaccessible place, using LEDs would virtually eliminate the need for routine bulb replacement.

Although the cost keeps going down, LED light bulbs are still expensive. A single AC bulb (17 LED), replacing a 25 watt incandescent, will cost about $40. Although LED's are expensive, the cost is recouped over time and in energy cost savings. Factor in that it is significantly cheaper to maintain led lights, the best value comes from commercial use where maintenance and replacement costs are expensive. Traffic lights and outdoor signs, for example, are being switched over to LED's in many cities. Smaller arrays, such as those in flashlights, headlamps and small task lights are great for specialty and outdoor use. LED based automotive headlights are current being used in high end luxury cars.

It will be interesting to see what developments are coming for more residential applications of LED lights. LED lighting technology has been researched and developed for the past two decades and we are beginning to see practical applications from this work. There is already wide spread use of LED traffic signs and LED headlights where a premium is placed on a reliable light source that is cheaper and less labor intensive to maintain. We in the industry are certain that tomorrows LED lights will last longer and consume even less power than todays energy efficient led light bulbs. LED lighting will be used to replace virtually every type of light, bulb, and lamp that is currently in use.