Microwave-powered ultraviolet lamp

When most people think of electric lighting, they think of ordinary lamps used for lighting rooms or shops. But many types of lamps are made for use in highly specialized applications. One example is a successful product made by Fusion Systems. Founded by four scientists and an engineer, the company markets an ultraviolet (UV) lighting system powered by microwaves. Introduced in 1976, the system found a market in industrial processing as a fast, efficient way to cure inks. A major brewery, for example, purchased the system for applying labels to beer cans and quickly curing their inks while the bottles went down the production line. U.S. patents issued for this lighting system include 3872349, 4042850 and 4208587.
The lamp seen here, referred to as a "TEM lamp" is a typical production unit. As in a fluorescent lamp, this lamp makes ultraviolet light by energizing mercury vapor. Fluorescents and other conventional lamps pass an electric current between two electrodes to energize the mercury. But Fusion's lamp has no electrodes. Instead the lamp is placed in a specially made fixture similar in principle to a household microwave oven. The microwaves energize the mercury vapor directly. A small dose of metal halides is also energized in the lamp. The choice of metal halides allows specific wavelengths of light to be produced to meet different needs.
Profits made from the production of this industrial lamp were used by the company to support research and development of a microwave-powered lamp that made visible light. Instead of mercury that lamp used sulfur. However this sulfur lamp did not sell well when introduced in the mid-1990s.
Lamp characteristics: Clear quartz tube containing a metal-halide pellet and a drop of mercury. No electrodes. The air-cooled tube is radiated by microwaves and produces ultraviolet light.
Object Name
discharge lamp
date made
ca. 1996
Date made
ca 1996
Fusion Lighting, Inc.
Physical Description
quartz (overall material)
mercury (drop material)
metal halide (pellet material)
overall: 10 1/4 in x 1/2 in; 26.035 cm x 1.27 cm
Place Made
United States: Maryland, Rockville
ID Number
catalog number
accession number
Energy & Power
See more items in
Work and Industry: Electricity
Data Source
National Museum of American History, Kenneth E. Behring Center
Credit Line
from Fusion Lighting Inc.
Turner, B. P.; Ury, M. G.; Leng, Y.; Love, W.G.. Sulfur Lamps -- Progress In Their Development
Publication title
Lighting A Revolution
Publication URL

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