ABSTRACT
In 1959, E.G. Fridrich and E.H. Wiley of General Electric were granted a patent for a design that lead to the first commercial tungsten-halogen lamp. The late ’80s and early ’90s saw the introduction of halogen lamps made with an infrared reflective coating that increased the filament temperature and improved the lumen efficacy of the lamps. There were many types and sizes of linear halogen lamps that contained iodine crystals. Other lamps were introduced that used bromine gas. It was found that dosing bromine in with the fill gas made production much easier than trying to control the method of getting an unpredictable amount of iodine vapor into the lamp. Halogen lamps are used extensively in airfield lighting, photographic work, automotive lighting and in fiber optic devices. Photographic and television studios use halogen sources because of their good color rendition and high color temperature. Early television cameras required sources of 3200K to 3400K to match the film used.
