In 2007 existed incandescent lamps, a phenomenon intensified by the halogen cycle and the sophisticated schemes of reflector sources.

It was necessary to understand how to manage the visible radiation and the powerfull charge of infrared radiation that were part of that kind of technology.

There were also fluorescent sources that showed us how phosphores were able to turn ultraviolet radiation into visible radiation. Their collocation in the chromatic diagram showed their interaction with the sensitivity of the human eye.

Another memorable type of lamp is the gas-discharge lamp using metal halides. The effect is given by mixing rare earth elements wisely. Each of these elements releases radiation of specific wavelenghts. This amount of radiation produces a continuous luminous spectrum of high color saturation.

The LEDs, instead, were used essentially for signalization. Many of the concepts we have mentioned have been applied, reproduced and expanded on the basis of this physical priciple.