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
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.