LIGHTING UP

Advances in micromachining and polymer processing have led to the realisation of an optical lighting film that can compete with mercury lamps

Recent advances in precision micromachining and polymer processing have led to the commercialisation of the Light Pipe by 3M. The Light Pipe itself is the outcome of 10 years of development into the area of Optical Lighting Film (OLF) which can transport and distribute light very efficiently with minimum losses due to absorption and transmission.

OLF is manufactured by a 3M microreplication process that forms very precise prisms on one side of an acrylic or polycarbonate film, with a smooth mirror like finish on the other. Light entering the film from the smooth side is uniformly distributed by the prisms.

The reflectance efficiency of OLF has been calculated as approaching 99%. Installed within an acrylic pipe, the film produces a very uniform intensity distribution throughout the length of the pipe. When used with a high intensity lamp at one or both ends, the light pipe distributes light through the microscopic prisms on the surface of the OLF.

Light can be distributed directly from the light pipe or transported through it from the light source to a remote location where illumination is desired. Because the designer can locate heat sources, such as the lamp and ballast, away from hazardous or low temperature areas, safety is increased and maintenance and cooling costs are reduced.

Light pipes have been used with a variety of light sources, but most effectively with another new type of lighting technology, the electrodeless sulphur lamp from Fusion Lighting. The golf-ball sized lightbulb contains a small amount of sulphur and inert argon gas. When the sulphur is bombarded by focused microwave energy, it forms a plasma that glows very brightly, producing a light similar to sunlight. The light is so intense that it can be distributed by the light pipe over a very large area.

The light pipe/sulphur lamp combination has already been successfully installed at the Smithsonian National Air and Space Museum in Washington, DC. Originally, the museum’s Space Hall, as it is called, was lit by 94 conventional mercury lamps using 29,000W of energy. Now, it is lit by three 1000W sulphur lamps that are installed in three 90ft long light pipes.

Figure 1: Optical Lighting Film is installed as the interior lining of a 3M Light Pipe

Figure 2: The Light Pipe and electrodeless microwave sulphur lamp offer an innovative way to distribute light

Figure 3: The Smithsonian National Air and Space Museum in Washington, DC has been lit up with a new light pipe/sulphur lamp system with components from 3M and Fusion Lighting

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