quartztungstenhalogen

Quartz tungsten halogen (QTH) lamps are a subclass of incandescent lamps characterized by a tungsten filament enclosed in a fused quartz envelope filled with a halogen gas (iodine or bromine) and a noble gas such as argon. The halogen cycle causes evaporated tungsten to react with the halogen and redeposit on the filament, enabling higher operating temperatures, a compact envelope design, and relatively longer life for an incandescent lamp. Because the quartz envelope withstands higher temperatures than ordinary glass, QTH lamps can operate at higher brightness with a stable color temperature and good overall performance.

Construction and operation: The quartz envelope and high-temperature filament produce a bright, white light with good color rendering. They are available in mains-voltage and low-voltage versions (the latter often using a transformer). Typical color temperatures range from about 2700 to 3200 kelvin, providing a warm to neutral white light. The lamps usually have a lifespan of roughly 2000–4000 hours, shorter at higher wattages or under harsh operating conditions.

Usage and applications: QTH lamps have been widely used in theatre and studio lighting, film and video lighting, projection, architecture lighting, and in some automotive headlights in earlier designs. They are valued for instant full brightness, good dimming response, and excellent color rendering, but they consume more power than modern LEDs and generate significant heat.

Safety and handling: The lamps operate at high temperatures and must be handled with care. Avoid touching the glass with bare skin, as oils can weaken the envelope. They require appropriate fixtures with adequate cooling, and should be replaced with the same wattage and type to maintain light quality.