Optical Fiber Draw

In 1965, the British Post Office sought a way to replace copper cables with light beams to transmit voice. The logical material for light pipes was glass–and Corning was ideally suited to pursue the possibility.

Corning physicist Robert Maurer enlisted scientist Peter Schultz and engineer Donald Keck in the effort. In a race against other large communications companies, they researched materials and processes others would not have been likely to even consider using for such a purpose.

Their experiments succeeded in 1970. The last to leave for the weekend, Keck lined up a laser at a batch of fiber for one final test. When he crossed the lab, a blast of bright light hit him in the eye. They had finally developed an optical fiber that could maintain laser light signals over significant distances.

Using outside vapor deposition (a process invented by Corning scientist J. Franklin Hyde in 1935), fiber is formed from ultra-pure, vapor-deposited chemicals. Layers of glass soot accumulate on a rotating bait rod, which is subsequently lowered into a consolidation furnace. The resulting blank or boule is lowered into the fiber draw furnace. Heat, gravity and a pulling system draw the glass to form a thread of pure optical fiber, the diameter of a human hair, which retains its original dimensionality.

Today, nearly all of the more than 25 million kilometers of optical fiber in America are based on this early prototype. The innovation paved the way for fiber optic telecommunications and, later, the Internet. It also placed Corning at the cutting edge of the fiber optics industry and earned Maurer, Keck and Schultz the 2000 National Medal of Technology.

ContinuousMelting

A periodic shortage of natural gas in the late 1930s compelled a Corning Research Laboratory group led by Charles DeVoe to investigate melting glass by means of an electric current directed through the glass bath. The process would allow melting entirely by electric power, but the team soon realized this process might have other benefits.

Since it melted the various ingredients in the bath evenly, from the inside out, electric melting minimized surface volatilization and showed promise for the production of optical glass. DeVoe’s experiments with electric melting and with platinum-clad stirrers that mixed the glass ingredients as they melted resulted in the “Continuous Unit” Melter. Using a specialized furnace with a complex stirrer, the continuous unit melter combined heat generated electrically and through combustion. Continuous melting produced high-quality optical glass more efficiently and in larger quantities than was possible with discontinuous pot furnaces, which made glass in clay pots that were replaced after each melt.

The first fully functional continuous melting unit came on line in January 1945. For the first time, large volumes–up to 100 pounds per hour, and several times that in later years–of uniform-quality optical glass could be continuously melted and delivered to automatic forming equipment. These machines transformed the glass into a multitude of products, from eyeglasses to camera lenses to large blanks of optical glass for military use.

BorosilicateGlass

In the early 1900s, the increased use of kerosene for railroad switch lanterns provided brighter lights, but the new fuel also resulted in higher flame temperatures. When hit by rain or snow, the lantern globes often shattered from thermal shock, making the lantern potentially unusable and disrupting train operations. Corning took on the challenge to develop a glass that could withstand sudden changes in temperature.

Drawing on the glassmaking experiments he had seen in Germany, Dr. Eugene C. Sullivan, joined by William C. Taylor, doggedly sought a formula to combine thermal shock resistance with chemical stability. In 1909, they created Nonex®, a lead borosilicate, low-expansion glass with excellent thermal shock resistance. Nonex’s durability meant fewer broken lantern globes, which helped save lives and property, but it also meant less repeat business for Corning. The search began to find an alternate composition of the glass for use in new applications–cookware.

In 1913, physics professor Dr. Jesse T. Littleton joined Corning to lead investigations into Nonex’s cookware potential. A breakthrough came outside of the lab, when his wife, Bessie, baked a delicious sponge cake using two Nonex battery jars. The confection prompted Sullivan and Taylor to derive a non-lead composition of the low-expansion borosilicate glass: Pyrex®.

Pyrex’s demand for high melting temperatures made it a challenging material both to work with and to produce cheaply, so Corning developed new processes for melting and forming, including pressing for cookware and drawing for tube and sheet glass applications. Corning also created a test kitchen to determine the best shapes and sizes for the cookware. Pyrex products soon became a staple in American kitchens.

In 1915, Pyrex found use outside the kitchen, as the basis for a full line of superior laboratory ware. By 1919, Pyrex ware was so successful that Corning became the market leader in the science ware business.

In the 1920s, Sullivan and Taylor continued to refine Pyrex’s composition, resulting in 15 different glass products in four new industries–and a new technical strategy. The premise of “special glasses for specific purposes,” later called “engineering materials,” created opportunities in product and process development that yielded success and growth for Corning over the next 80 years.

In the early 1960s, Corning embarked on a safety windshield project designed to strengthen windshield glass, which would reduce the threat of laceration during car accidents. In response to this need, Corning researchers Stuart Dockerty and Clint Shay engineered the “fusion draw” method for producing very thin, flat glass, which could then be chemically strengthened to make it stronger, and thus safer.

During the fusion process, molten glass flows evenly down both sides of a trough called an “isopipe,” then it rejoins, or “fuses” together, below to form a single sheet of flawless, flat glass. Since the sheet is fused in air, neither face of the glass is touched, resulting in pristine and smooth surfaces that require no subsequent grinding or polishing.

Corning discovered that the process was the optimal technology for the manufacture of liquid crystal display (LCD) screens. In the 1980s, Corning researchers mounted a campaign to refine the product’s attributes to reduce the level of defects and improve the glass sheet’s dimensional and stress properties. Ongoing refinements led to the creation of defect-free LCD glass of all sizes, which became the cornerstone of Corning’s leadership in the LCD industry. Today, Corning glass is used in millions of LCD displays for televisions, desktop computers, laptops, cell phones and other electronic devices.

Fusion Draw