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Microgravity Fiber-Pulling Apparatus

This fiber-processing method provides a way to produce optical fiber composed of glass systems in microgravity.

Marshall Space Flight Center, Alabama

A method to process optical fiber composed of glass systems has been developed in support of the space shuttle and Space Station programs. This process, known as the Microgravity Fiber-Pulling Apparatus, was designed to operate in a microgravity environment. It has the unique capability to produce heavy-metal glasses through the reduction of nucleation and allows low viscosity to be handled more easily. Optical fibers, such as the heavy-metal fluoride glasses, are usually very difficult to process in ground-based operations because the glass has inherent characteristics such as low viscosity, a narrow working range, and a tendency to form crystallites during processing. Operation in microgravity has demonstrated that some of the conventional methods used in Earth-based fiber-forming processes will not function properly in a weightless environment. For example, the gravitational force necessary to initiate the fiber draw is not present in space. The components of this fiber-pulling apparatus include a source of the glass (preform), a sting to initiate the fiber-drawing process, a coating applicator for ultraviolet-curable cladding, an ultraviolet lamp, and a reel to place the drawn fiber on after it has been cooled. These components are shown in the figure. Processing the glass system in microgravity is the most important step to forming more perfect fiber composed of the heavy-metal fluoride glasses. In microgravity, processing glass systems requires a sting (consisting of a platinum wire with a flat plate or fingers at the extremity) to pull molten glass out from the drawing aperture. Since current drawing chambers designed for space platforms do not allow extremely large volumes for fiber drawing, this design uses a chill block to quench the glass melt into a solidified fiber. Another drawback to conventional methods of processing fiber is the coating applicator, which needs to be completely contained and have the ability to operate through a fluid-transfer line to provide uniform cladding on the fiber. A syringe-type or peristaltic pump provides this apparatus with the appropriate capacity and pressure. Another drawback to conventional methods of processing fiber is the coating applicator, which needs to be completely contained and have the ability to operate through a fluid-transfer line to provide uniform cladding on the fiber. A syringe-type or peristaltic pump provides this apparatus with the appropriate capacity and pressure. Components of the Microgravity Fiber-Pulling Apparatus include a source of glass (the preform), a sting to initiate the fiber-drawing process, a coating device, an ultraviolet curing system, and a take-up reel to place the fiber on after it has cooled. This work was done by Dennis Tucker of Marshall Space Flight Center and Gary Workman and Guy A. Smith of the University of Alabama in Huntsville. For further information, access the Technical Support Package (TSP) free on-line at www.nasatech.com under the Manufacturing/Fabrication category. MFS-26503

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