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NIST Industrial Impact

Company: Corning Inc., Corning, New York
Business: Makers of consumer housewares and specialty materials including optical fibers

Company: AT&T Bell Laboratories, Atlanta Works, Norcross, Georgia
Business: Providers of communications services and products, computer systems, and network equipment including optical fibers

As you read this, the world is becoming ever more wired with optical fibers. Growing networks of millions of kilometers of glass fibers cross continents and oceans linking millions of people and computers worldwide with pulses of information-laden light. Without optical fibers, any talk of a National Information Infrastructure would be little more than a pipe dream.

With all of this growth, the need for optical fiber makers and users to standardize products, manufacturing processes, and installation procedures becomes critical. Lacking that, technical incompatibilities that would stunt growth of these networks, hinder their maintenance and repair, and thereby erode the international competitiveness of the U.S. telecommunications industry could emerge. This challenge is a classic call to arms for researchers at the National Institute of Standards and Technology.

Since 1981, NIST has been working closely with the Telecommunications Industry Association to advance both standards and technology for the optical fiber industry. A 1992 report prepared for NIST by an independent economist estimated that NIST's aid in the development of standards and measurement protocols had by then been responsible for annual savings of $9.5 million in the optical fiber industry, which was more than four times the cumulative cost of the collaborative work throughout the entire 1980s.

A recent NIST contribution that has been getting particularly high praise from the industry goes by the unassuming name of SRM 2520. SRM stands for Standard Reference Material, and SRM 2520 is one of about a thousand different SRMs that NIST prepares for hundreds of industries that need reliable benchmarks by which they can calibrate their own tools, instruments, chemical analyses, and other measurement protocols.

At the heart of each SRM 2520, which companies can purchase from NIST for about $1,000, is an optical fiber whose diameter has been more accurately measured and certified than any other fiber
in the world. To certify each standard, NIST metrology expert Ted Doiron designed and built an exquisitely sensitive and accurate micrometer that could measure fiber diameters with an uncertainty
of about 50 nanometers or the width of about 100 molecular layers of the glass. In the hands of the engineers at an optical fiber plant, an SRM 2520 serves as the most reliably calibrated ruler by which they can monitor the uniformity of their own commercial fibers, explains Matt Young, who developed SRM 2520 with Steve Mechels, Paul Hale, and other NIST researchers.

SRM 2520 has become a necessary tool in the production of optical fibers even though the standard only became available in 1993, according to Jan H. Suwinski, an executive vice president of Corning Inc. At the center of the standard fiber is a glass core about 10 micrometers in diameter surrounded by a thicker glass cladding whose outer diameter is about 125 micrometers, or about two hair-widths. (The cladding is coated with a tough polymer to protect the glass from environmental degradation and breakage.)

The particular value of SRM 2520 is emerging as optical fibers reach from major optical cables to individual buildings, homes, and offices. This phase of network growth entails massive amounts of splicing and matching of fibers, which can be more expensive than stringing fibers longer distances, a procedure requiring fewer splices. Industry experts say that variation in fiber diameters would be calamitous because, if the diameters differ, the inner cores probably would fail to align precisely when joined, resulting in degraded light signals. And that spells "disaster" for an industry whose raison d'ˆtre is transmitting signals reliably and clearly. By using SRM 2520 to calibrate the fiber-making process, the optical fiber industry can increase the likelihood that its fibers will align. According to Department of Commerce statistics, the U.S. optical fiber market amounted to $2.1 billion in 1992, which was 40 percent of the world total. That translates into a lot of splicing.

"Another industry-wide study found that the main problem in controlling the cladding diameter was having a reference," notes William Gardner, who specializes in fiber measurement standards at AT&T's optical fiber plant in Norcross, Ga. With SRM 2520, he says, uncertainty in the measurements of fiber diameters now vary within about one-tenth of a micrometer (about the width of a cell nucleus), which is about one-tenth of the uncertainty that was typical before SRM 2520 became available. Both AT&T and Corning now use SRM 2520 routinely for quality control.

In a letter to Judson French, director of NIST's Electronics and Electrical Engineering Laboratory, Corning's Suwinski wrote that "the opportunity to work with NIST on this project gave Corning and other American fiber manufacturers a clear competitive advantage."

For NIST, that kind of industry feedback translates into a mission accomplished. But not completed, notes Young. NIST and the optical fiber industry now are planning to work on other standards, including one for measuring the tiny diameters of ceramic ferrules that are used to connect fibers into continuous pathways of light.

March 1994