page_title: Sulfur lamp
section_title: Light pipes
hierarchical_section_title: Sulfur lamp / Light distribution systems / Light pipes
caption_attribution_description: English: Sulfur lamps with light pipes on the ceiling of the U.S. Air and Space Museum in Washington, D.C.
context_page_description: The sulfur lamp is a highly efficient full-spectrum electrodeless lighting system whose light is generated by sulfur plasma that has been excited by microwave radiation. They are a particular type of plasma lamp, and one of the most modern. The technology was developed in the early 1990s, but, although it appeared initially to be very promising, sulfur lighting was a commercial failure by the late 1990s. Since 2005, lamps are again being manufactured for commercial use.
context_section_description: The 3M light pipe is a long, transparent, hollow cylinder with a prismatic surface developed by 3M that distributes the light uniformly over its length.  Light pipes can be as long as 40 metres (130 ft) and are assembled on site from shorter, modular units.  The light pipe is attached to the parabolic reflector of the sulfur lamp.  For shorter pipes, there will be a mirror at the opposite end; for longer ones, there will be a lamp at each end.  The overall appearance of a light pipe has been compared to that of a giant-sized fluorescent tube.  One sulfur lamp with a light pipe can replace dozens of HID lamps.  In the National Air and Space Museum, three lamps, each with a 27-metre (89 ft) pipe, replaced 94 HID lamps while greatly increasing the amount of light delivered.
  The greatly reduced number of lamps may simplify maintenance and reduce installation costs but may also require a backup system for areas where lighting is critical. The light pipes allow the lamp to be placed in an easily accessible area for maintenance and away from places where the heat of the lamp may be a problem.
caption: Sulfur lamps with light pipes on the ceiling of the U.S. Air and Space Museum in Washington, D.C.
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