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Light Sources Semiconductor Components Standard Components Sensors and Switches Clutches, Motors, and Solenoids Other Electrical Components Consumables Light Sources Our products use a variety of different light sources. These range from intense sources such as halogen lamps to relatively weak sources such as LED arrays. The light source selected depends on the function--original exposure, quenching, etc.--and the machine design. The most important light sources from a design point of view are those commonly used for original exposure (scanning)--the halogen lamp, the fluorescent lamp, and the xenon lamp. The most basic characteristics of these three lamps are summarized in the following table. Halogen Fluorescent Xenon Light Intensity High Low Low Spectrum Wide Narrow Narrow Temperature dependency* Small Large Large Stability at start-up Good Poor Good Heat output Large Small Smallest Cost High Low Lowest *Dependency of light intensity on temperature of these three lamp types. 1 April 2001 Page 980 Standard Components Light Sources Halogen Lamp A Halogen lamp is an incandescent lamp filled with halogen gas (iodine or bromine). The halogen gas suppresses filament evaporation using a chemical regeneration process known as the "halogen cycle" (see below). Halogen lamps have a long effective life and strong light output. Characteristics · Extensive spectrometric distribution · High illumination level halogen.pcx · Small changes resulting from the temperature of the light source and small transient changes · Long lead time to lighting · Large electricity consumption · Large heat output Halogen Cycle During lamp operation, the halogen gas combines with tungsten molecules that have evaporated off the filament. The evaporated tungsten molecules are then deposited back onto the filament, instead of on the lamp wall. Consequently, there is almost no reduction of light output from lamp wall darkening. Some