The halogen lamp is made of tungsten wire, but it is enclosed in a smaller quartz glass bulb. Because the glass bulb is very close to the filament, if it is made of glass, it will melt easily. The gas in the glass bulb is composed of different gases to form a halogen lamp group. These gases have an interesting property: they combine with tungsten vapor. If the temperature is not high enough, the tungsten atoms combined with the halogen gas evaporate and redeposit on the filament. This cycle process makes the filament last a lot of time. In addition, it can run hot filaments, which means you get more light energy. You still get a lot of heat, but because the quartz bulb is so close to the filament, it is hotter than a normal light bulb.
Halogen bulbs can also operate at a higher temperature than ordinary incandescent lamps, and their brightness and efficiency are also higher. However, at this temperature, ordinary glass may soften, so halogen bulbs need to use quartz glass with a higher melting point. Since quartz glass cannot block ultraviolet light, halogen bulbs usually require an additional ultraviolet filter.
If there is oil on the crystal glass on the halogen bulb, it will cause the temperature on the glass to be different and reduce the life of the bulb. Therefore, avoid touching the glass of the bulb when changing halogen bulbs. If you touch it with your fingers, clean it with alcohol.