Sandia National Laboratories have discovered that the human eye is comfortable viewing under white light emitted by the diode lasers as well as under light emitted by LEDs.
The light is generated by passing electric current through the respective materials by both devices. In case of LEDs they emit light through spontaneous emission, while lasers produce light by its bouncing action. The discovery by Sandia will further enable LEDs to replace the traditional tungsten bulbs as light sources, with their higher lighting efficiency. However, the efficiency of the diode lasers is much higher when compared to LEDs.
One of the researchers at Sandia explained that they had to face the challenge of convincing people about the lighting capacity of diode lasers before going ahead with experimental proof. Prior to the experiment the common assumption was that the quality of light emitted by diodes was of poor quality and not very pleasing for viewing. Another fact was that the light from the diodes was much narrower when compared to that of LEDs. The tests were conducted at the University of Mexico’s Center for High Technology Materials. A group of forty volunteers were made to sit in front of two identical scenes of fruits in bowls. These were kept in adjacent chambers and illuminated by different sources like white LEDs, tungsten filament bulbs, lasers etc. Viewing preferences of the participants were recorded without disclosing the type of light source to them. The computer programming for changing the sources was written by a doctoral student. Each of the participants was made to choose between changing light sources for as many as 80 times. The entire experiment spanned for twenty minutes. Out of the results five were disqualified when the participants were proved to be color blind. The summed results showed that the preference among the group was more towards diode-laser based lighting when compared to LED light sources.
Diode lasers are slightly costlier to make when compared to LEDs, however blue diode lasers are being preferred by automobile manufacturers for their headlights. One of the researchers explained that the best way of using diode lasers will be to alternate between the colours for various applications. He explained that blue light can be used for illuminating phosphorus, used for fluorescent lighting.