Incandescent lamps

10266913_l_Olivier Le QueinecAn incandescent lamp produces light through heating a filament. Most energy is radiated in the infrared (IR) area (as heat instead of light), which results in a very low efficiency. The health risks are minimal. Because they waste so much energy, the European Union has decided to gradually withdraw incandescent lamps from the market.

 

Halogen lamps

26363262_l_Chayatorn LaorattanavechA halogen lamp is an incandescent lamp, where the bulb is filled with an inert gas under high pressure. To this gas a small amount of halogen (bromine or iodine) is added, from which the lamp gets its name. A halogen lamp works at a very high temperature. This is why its optical spectrum has shifted to the blue part, resulting in more UV light and less infrared emitted. In order to stop the harmful UV light, halogen lamps are made of a special type of quartz (“doted” quarts) or provided with special casings/filters.



Fluorescent lamps

854441_l_ bratan The tube of a fluorescent lamp is covered on the inside by a fluorescent layer and is filled  with mercury gas under low pressure. An electric tension between electrodes at the end of the tube excites the mercury gas, producing ultraviolet light. In the fluorescent layer the UV light is converted into visible light. The fluorescent layer is not always perfectly homogeneous and lets pass a bit of UV light .  This is why a fluorescent lamp gives a bit of ultraviolet and blue light. The most well-known examples are the fluorescent lamp tubes and the compact fluorescent lamps, CFL (also called energy saving lamps).

Compact fluorescent lamps also produce non-optical electromagnetic fields of intermediate frequencies (30-60 kilohertz, kHz). They do not transmit radio waves, reason why they cannot be compared with mobile phones (as is done sometimes). Even the most prominent type of radiation (of 30–60 kHz) lies under the exposure limit if one maintains some distance to the lamp (a few centimetres).

 

LED
16245722_l_Anton StarikovLED lamps (LED, “Light Emitting Diode”) are not lamps in the traditional sense of the word. They do not have a glass bulb and do not contain a filament. The light arises in a crystal made of a semi-conductor, which illuminates if a current is sent through it. All this solidly wrapped in a transparent casing of epoxy resin.
LEDs give light in one specific colour (red, green, blue,…) and there are also infrared or UV LEDs. White light in LED lamps is obtained through illuminating a fluorescent layer by blue or UV light. Nowadays there are also variations which emit white light directly, as a result of the composition of the crystal (such as RGB LEDs). LED lighting does not give infrared or ultraviolet radiation, with the exception of LEDs where the white light is obtained by means of UV light. Blue and cold white LED lamps emit relatively large amounts of blue light, which may pose a health risk (“blue light hazard”).

You can download all information of this section in its entirety as a pdf document (info sheet “Lamps and radiation”).