ber at low temperatures and bending it until it breaks. The key, Gupta says, is ensuring that a sample is completely free of flaws before the test. Gupta isn't surprised that no one has definitively measured the strength of fiberglass before now. "Industries develop materials quickly for specific applications," he says. "Later, there is time for basic research to further improve a material." To improve a particular formulation of glass and devise new applications for it, researchers need to know how strong it is under ideal conditions. Therefore, Gupta and his colleagues-Charles Kurkjian, formerly of AT&T Bell Labs and now a visiting professor of ceramic and materials engineering at Rutgers University; Richard Brow, professor and chairman of ceramic engineering at University of Missouri-Rolla; and Nathan Lower, a masters student at Univer- sity of Missouri-Rolla-had to determine the ideal conditions for the material. In their latest work, the engineers outlined a set of procedures that researchers in industry and academia can follow to assure that they are meas- uring the ideal strength of a glass fiber. For instance, if small-diameter versions of the fiber seem stronger than larger-diameter versions, then the glass most likely contains flaws. That's because the ideal strength depends on inherent qualities of the glass, not the diameter of the fiber, Gupta says. To measure the ideal strength of E-glass, Gupta and his coresearchers experimented on fibers that were 100 um thick-about the same thickness as a human hair-held at minus 320°F. They bent single fibers into a "U" shape and pressed them between two metal plates until the fibers snapped at the fold. The fibers withstood a pressure of almost 1.5 million pounds per square inch-roughly 1.7 times higher than previously recorded measurements of 870,000 pounds per square inch. The results suggest that the engineers were able to measure the material's true strength. Given the telecommunications industry's current slump, however, Gupta doubts that optical fiber mak