Signs, sensors and nondestructive testing

Most contractors, as installers of building cabling systems and those involved with telephone companies, CATV or utility outside plant installations, are familiar with fiber optics. Fiber optics, however, has other applications besides communications, some of which may be business opportunities for electrical contractors.

Even specialized communications applications are expanding. Several new fiber optic networks using plastic optical fiber (POF) have been adopted by automotive manufacturers. Last year, about 5 million entertainment and communications devices connected with POF were installed in vehicles. POF is also used to connect air bags and other safety devices in vehicles because of its high reliability.

Medical applications for fiber optics probably don’t have a lot of business interest for contractors, but some may be familiar with the applications because they have had a recent gastrointestinal screening by endoscope. Fiber optics has long been used for medical applications since it allows nonsurgical viewing of the internal human body for diagnosis.

Using bundles of fibers, some of which transmit light into the body and others that capture an image for viewing, endoscopes have become one of medicine’s everyday tools. Recent advances in endoscope construction allow the repair of joints or even hernias using laparoscopic surgery through tiny incisions. The result is much less patient trauma.

Nondestructive testing also uses endoscopes to visually inspect hard-to-reach areas such as the inside of engine cylinders, pipes or even sailboat masts. You may have encountered this when working around engines, pipelines or pumps.

Fiber optics is being used for sensors. Using sophisticated techniques, fiber can be made into microphones, electrical (voltage and current) sensors, chemical detectors and intrusion systems for perimeter protection. Fibers can even be imbedded in concrete structures such as bridges or buildings to monitor stress and detect internal cracks.

Fiber optic sensors all seem to share two features: they are much more sensitive than other types of sensors and much more expensive. Many of the applications are military, where the sensitivity is desirable and cost is not an object, but industrial and utility applications are increasing. Installation of these sensors often requires long fiber optic cable runs, sometimes in difficult remote locations, requiring an experienced contractor’s services.

Fiber optics can be used in signs, either by piping light to a small section of a sign, illuminating a mask or creating a shape, or by creating a matrix that can be selectively lit to create dot-matrix displays. Fiber can also create unique visual effects not easily duplicated with lamps or LEDs. Fiber optic signs are all custom-made and installed ready to wire up and turn on.

The most likely noncommunication fiber optic installation you have encountered is probably lighting, and we mean beyond the fiber optic Christmas trees. Fiber is optimized for delivering light over a distance with low loss, which makes it perfect for lighting. Fiber optic lighting has many advantages over conventional lighting that often justify its higher cost.

Probably the most obvious application is lighting swimming pools and fountains. Because fiber acts as both a light pipe and an insulator, the actual light source can be remotely installed, well away from the water, removing any hazard of electrical shock. Individual fibers can be filtered for spectacular color effects. Multiple fibers can also share one light source, making this application highly efficient.

I have seen many applications of fiber optic lighting recently in museums, where it is used as a source of “cold” light to protect delicate artwork. Fiber optic lighting is easily directed and focused, allowing even small objects to be brilliantly lit. Since the light source is remote so is the heat, and the source can be filtered to produce pleasing light that is not harmful to the valuable item being lit.

There have been many attempts to find ways to use fiber to distribute light inside a building. I remember seeing patents more than 20 years ago where lenses or mirrors would gather sunlight and focus it into fibers for distribution inside a building. I believe the U.S. Navy even considered using it for shipboard lighting. But the cost has always been too high, especially when you consider alternative light sources (electrically powered, of course) are needed for cloudy days or nighttime.

I’m sure electrical contractors who install lighting have become familiar with fiber optic lighting, just as those installing Category 5 or coaxial have leaned all about fiber optics for communications. The applications are quite different, with little commonality in fiber types, connectors, light sources, installation tools and test equipment. But as in any specialized field, if there is a profitable business there, it’s probably worth pursuing. EC

HAYES is a VDV writer and trainer and the president of The Fiber Optic Association. Find him at