1995 Xycarb #255860 (2000 W / 120 V)

Tungsten halogen lamps are commonly used a source of infrared energy in various industrial processes for e.g. material treatment, the drying of paint and goods, and other high-temperature applications. In the vast majority of cases these infrared lamps are of the linear double-ended kind and are assembled in banks when high irradiation levels are needed to heat large surface areas. However, certain processes, like chemical vapor deposition (CVD) or surface melting, require a very local application of heat that can only achieved with compact sources having an extremely high optical output density.

The lamp presented here belongs to that latter category of infrared sources and was made by Philips for Xycarb, a manufacturer and supplier of material processing machines and of ceramic and semi-conductor materials for the microelectronic industry. The 2-kW #255860 is based on stage & studio quartz halogen lamps, filled with an argon-dibromomethane mixture and provided with a compact low-voltage coiled-coil tungsten filament designed to operate at around 2400 K for an optimum optical emission in the near-infrared with a peak wavelength at 1200 nm. The reduced operating temperature of the tungsten radiator results in a service life extended to 5000 h. The high dissipated power combined with a short filament structure translates into a linear optical power density of about 580 W/cm, which is more than twice as high as that of the largest double-ended infrared sources.

Such intense source of radiation is usually coupled with a water-cooled elliptical mirror that focuses the emitted light onto the material surface to be treated. In usual cases that's a silicon wafer located inside a transparent CVD reactor made of fused silica. The extremely high optical power density achieved at the point of light focus brings the material surface to a high enough temperature resulting in a change of its crystalline structure, its phase, or in the epitaxial growth of material as a result of chemical reactions occurring between the CVD reactor's molecular atmosphere and the extremely hot material surface. While those processes could also be driven with lasers and xenon short-arc lamps, incandescent sources are very much cheaper and more convenient, which still makes them the standard source of infrared energy in high-temperature material processes whose involved surface area is not too small.