Date: Thu, 18 Dec 1997 02:46:43 GMT Server: BESTWWWD/1.0 MIME-version: 1.0 Content-type: text/html Content-length: 13568 Last-modified: Sat, 01 Feb 1997 20:51:12 GMT Fiberstars' Fiber Optic Lighting Systems Overview

Fiber Optic Lighting Systems:
An OVERVIEW


When it first appeared as a commercially available product about a decade ago, fiber optic lighting was both a boon -- and something of a disappointment as well.

A boon because fiber optic lighting, then as now, offers a host of advantages unavailable with traditional forms of lighting in any application, indoor or out, commercial or residential. By its nature, fiber optic lighting is generally energy efficient.

Technological advances have made it more so today. To provide illumination over a given area, only a single halogen or HID light source is required to power all or part of a particular fiber optic installation. Fiber optics can readily supplant multiple electrical light sources that usually add up to greater wattage. The illuminator can also be located remotely, at or near floor level, convenient to maintenance checks and for eventual lamp replacement of that single source.

Then as now, the only electrical connection needed for a fiber optic lighting installation is at the illuminator. No wiring and no electrical connection is needed along a given length of fiber optic cable or at a fiber optic point-source fixture.

No wiring and no electrical transmission also mean no additional heat enters the space being illuminated -- and, thus, requires no compensation or removal by ventilation and air conditioning systems. Further, no electrically generated light at the fixture means no harmful, fade-causing UV is added to a space, nor are electromagnetic fields which can interfere with sensitive electronic equipment. In sum, fiber optic lighting requires no voltage at the fixture; emits no heat; is completely safe; and is virtually maintenance free.



With all of these advantages to fiber optic lighting, you might ask, "What was the disappointment?" Primarily it was a lack of sufficient illumination for certain applications, when compared to traditional light sources and fixtures. Early illuminators, though larger in size than today's models, had comparatively lower lumen output. Fiber optic cabling was sometimes a problem, too. Clear plastic outer tubing used to encase the fiber optic strands for side-emission was less densely packed than the best of today's systems.

In the latter regard, the biggest single advance is a patented type of fiber cable known as BritePak. Here, the fiber optic strands are grouped into densely packed bundles that are twisted and drawn through a PVC outer jacket. This is a classic example of the sum being greater than the parts. Twisting noticeably heightens the amount of illumination released along the cable length, when fiber optics are used in linear or accent lighting applications, achieving very even output along a greater distance than ever before.



As more lighting manufacturers race to enter fiber optics, we should pause to recap the basics of any fiber optic system, before detailing some of the most notable advances that have come onto the market recently.

Fiber optic strands used for lighting are closely related to the plastic or glass fiber strands used to carry pulses of laser light from a transmitter to a receiving end in a telecommunications circuit. While fiber optic lighting has been most often applied for linear side-emitting applications, along the length of fiber optic tubing -- and often as a more cost-effective, trouble-free substitute for neon -- it can now to be used as a direct replacement for fixed and aimable point-source light fixtures.

Most optical fibers used for commercial lighting applications in the U.S. have a core material of plastic with a high refractive index and a cladding with a lower refractive index. Light rays generated from the illuminator are transmitted along the core material totally by internal reflection at the core/cladding boundary. These light rays travel through standard bends and are evenly emitted outward along the entire specified length of fiber optic cable, or through to the end for point-source lighting. It is important to note that achieving optimum performance in side-emitting vs. end-emitting applications will depend on the specific angle of focus for the fiber optic cable, when it is ported at the lamp/fiber interface on the illuminator. The fiber optic cabling used, and illuminator's power and features, should be matched for desired effect.

In North America and the Far East, with their advanced plastic-forming technology, plastic optical fibers are preferred for most applications. Plastic has excellent optical transmission of visible light. Fiber optic cable comprised of small-core strands is also highly flexible throughout its productive life -- which runs 20 years. Yet, it is virtually unbreakable and can be cut in the field as necessary. Most large core fiber, being a thermal set process, is limited to a specific length, 100 feet or less. With time, either in storage or in place, large-core fiber becomes very rigid. These factors make conventional large-core plastic difficult to manage on large projects. In Europe, where "basic" materials still predominate, glass fibers are more common. Glass fiber systems used for lighting typically offer shorter cable lengths, are often more expensive and cannot be cut for field fabrication.

A fiber optic system generally involves three components: the light source and its housing, the fiber optic bundle and, for end emission, the receiving-end fitting or fittings. A light generator housing or power source, called an "illuminator," uses a reflector to focus the visible light wave properly into one end of the fiber optic strands.

The number of light sources available for producing the fiber optic illumination has grown from a handful of MR16 tungsten-halogen lamps to include powerful, long lasting 150-and 400-watt metal halide lamps.

The illuminator, as an option, can be fitted with a dichroic glass color filter wheel to provide a continuous or fixed change of color. Computerized programming controls can be used to provide special effects, such as timed light changes or strobe-like bursts of light. Multiple illuminators can be synchronized. These can be integrated with music on a sound system or varied by time of day, greatly expanding the types of creative applications ideal for fiber optic lighting.

Infrared and ultraviolet wavelengths produced by a given light source have long been undesirable byproducts to an installation, for a lighting designer. Using fiber optics, these wavelengths can be easily filtered out prior to entering the fiber, eliminating the damaging effect of UV and IR to objects or materials being illuminated. Conversely, light in the visible spectrum is only slightly absorbed in traveling through the optical fiber, with red wavelengths in particular subject to attenuation.

Various types of aimable, reflecting or diffusing fittings at the end of fiber optic tubing are the final components that can be selected for today's fiber optic systems. This is where a lot of the excitement and creativity now resides with fiber optic lighting when it is used for indoor or outdoor point-source applications.



Until just recently, as indicated previously, most fiber optic lighting applications were linear. It has most often been used in signage, decorative or architectural accent lighting, replacing more trouble-prone and hazardous neon, or as a substitute for standard incandescent or fluorescent cove lighting.

Higher lumens per watt, new smaller-sized illuminators, and the advent of the bundled fiber, have most recently enabled fiber optics to be adapted to a broad range of point-source fixture heads. Such fixture heads have essentially taken two forms on a readily available production basis, outdoor (or, for that matter, indoor) landscape fixtures and recessed ceiling downlights.

The new types of outdoor fixtures which can be illuminated fiber optically include a broad complement of above-ground bollards, step and walkway lighting, path or border lighting, wall-washing or shrubbery-illuminating spot and flood lights, and in-ground fixtures. All are U.L. and CSA-listed, many for use in wet or damp locations. These latter points are particular strengths of fiber optic lighting since, you'll recall, no electrical current is transmitted from the illuminator to a fixture nor are there any lamps at the fixture head. This means a virtually maintenance-free fixture, no sockets or lamps to replace at the fixture.

The new fiber optic recessed ceiling downlights, like their more traditional counterparts, can offer aiming capability and light-enhancing lenses. A particular advantage here is that fiber optic downlights are quite unobtrusive. Only the trim is visible. The light source is, of course, remotely mounted and centralized for convenient lamp replacement. This means freedom to locate fixtures in those inaccessible areas where specifiers cannot use higher maintenance electrical fixtures. Fiber optic fixtures can replace more costly explosion-proof fixtures in hazardous or classified locations, and can easily be retrofitted into ceilings, walls or floors of existing spaces. With no heat in the light, they are also ideal for retail display cases. Plastic fiber is easily field cut and more resistant to damage than many standard lamp and fixture housings.

Like any high-technology product, applications and new-product developments for fiber optic lighting are outpacing the lighting industry as a whole. Each month, lighting designers who have never used fiber optics decide to try it on a project and design with fiber optics specifically in mind. End-users are also rapidly becoming aware of fiber optic lighting and increasingly inquire about or ask for it. An growing number of electrical contractors and other types of installers are finding out how easy it is to acquire experience with fiber optic systems. Fiber optics have recently been installed in locations as varied as the Louvre, Heathrow Airport, Barney's Madison Ave., and the Getty Mansion in Los Angeles, to say nothing of numerous corporate office and high-end residential applications.

The creative uses and effects that can be created with fiber optic lighting are nearly limitless and can be notably distinct from standard lighting solutions -- with less up-front development, lower installed costs and less maintenance required than with gerrymandered methods. The utter common sense and economy of remotely located, programmable single-light-source illuminators, powering a complete multi-fixture system, are increasingly difficult to ignore.



As with desktop computers and the Information Age itself, now is the time for lighting professionals to employ fiber optics for the benefit of clients, lest this rapidly advancing technology pass them by. The new generation of compact, powerful illuminators, highly luminescent tubing, and indoor/outdoor point-source fixtures, can combine to make fiber optics a routine part of any lighting designer's experience and vocabulary. Although much of the terminology of this emerging technology may seem at times relatively complex, the use of fiber optic lighting fares highly when evaluated against basic cost and performance (light output and energy savings) issues, in addition to its many creative aspects. Lighting professionals will find fiber optics more and more desirable for their installations.


        








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