Mar 2013

Light Sources Part III – Halogen

People ask me all the time about halogen light bulbs. Most of the questions are: Do they get hot? Yes they do get hot. Halogen lights bulbs are a form of incandescent lighting, and all incandescent light bulbs get hot. However halogen bulbs operate at higher temperatures because the gas inside the glass enclosure is under more pressure that regular incandescent light bulbs.

A Typical Halogen Light Bulb.

Because the halogen gas inside the capsule is under high pressure the capsule must be made of a hard quartz glass. They are sometimes referred to as quartz halogen. You should not handle the quartz bulbs with bare hands as the oil from your skin can shorten the life of the halogen light bulb.The filament of all incandescent light bulbs is made of tungsten. Halogen light bulbs have a longer life that regular incandescent bulbs because of something called the halogen cycle. During the halogen cycle tungsten is evaporated away from the filament and combines with the halogen. Then in a chemical reaction the tungsten is deposited back onto the filament and that extends the life of the light bulb. Halogen light bulbs can be smaller in size than other incandescent light bulbs so you find them in mini pendants and other small light fixtures. They also produce a pleasant white light usually about 3000K.

MR16 Halogen Directional Light Bulb.

Another popular halogen light bulb is the MR16. They are used in many track heads, recessed lights and landscape lights. The are a “mirror reflector” light bulb hence the name MR. The number 16 is the diameter of the face of the bulb. It is a directional light bulb that focuses a beam of light onto an object or work surface. This a very useful light bulb for lighting art, kitchen counters and other applications where a directional light source is needed.

Halogen bulbs in different shapes, beam spreads and lumen output are a necessary for tool for a lighting designer’s bag of tricks. Remember always pick the light bulb first then the fixture to house it. Different light bulbs do different things. You want to match the lighting task with the proper light source. That is what I do as a lighting designer. Please visit my website, fogglighting.com.