Types of luminescence

The photoluminescence occurs when the radiation absorbed by a solid is re-emitted with a different wavelength. When the re-emitted radiation is in the visible spectrum, the phenomenon is called fluorescence or phosphorescence.

Electroluminescence is a phenomenon that is taking place when the light is produced by an electric current passing through certain solid, such as phosphorous materials. It is used in illuminated signs and dashboards, but it has not proved to be a practical light source for indoor or outdoor lighting.

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The evolution of electric lamps


Although technological progress has made it possible to manufacture different lamps, it is the constraints of the external market that have been the main factors to influence their development. Thus, the production of filament lamps used in the early XX century became possible after the development of efficient vacuum pumps and drawing tungsten. However, large-scale electricity generation and distribution to meet the demand for electric lighting was key to market growth. Electric lighting offered many advantages over gas or oil lighting, namely a stable, low-maintenance light and better safety due to the absence of flame and combustion by-products.

During the reconstruction period following the Second World War, the focus was on productivity. The fluorescent tube became the main source of dominant lighting, as it allowed for a shade less and heat-free lighting of factories and offices, and therefore an optimal use of space.
Performance criteria
Performance criteria vary by application. In general, their relative importance does not correspond to any hierarchy.

Luminous flux:


The luminous flux of a lamp determines its good adaptation to the size of the installation and the quantity of light required.


Color Appearance and Color Rendering: Different scales and numeric values apply to color appearance and color rendering. It is important to keep in mind that these figures are for illustrative purposes only and that some are only approximations. As far as possible, adaptation assessments should be made with actual lamps and with colors or materials applicable to the situation.
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