NIST develops fast, accurate fiberoptic composite material monitor

A fast fiberoptic process monitor for use in producing lightweight composite materials developed by the National Institute of Standards and Technology (NIST; Gaithersburg, MD) could improve process control and eliminate the large or intrusive sensors called for by other techniques. The monitor uses a high-index lead-oxide-doped glass fiber and an argon-ion laser to measure chemical reactions and fluid flow inside a mold as a composite changes from liquid to solid form.

NIST develops fast, accurate fiberoptic composite material monitor

A fast fiberoptic process monitor for use in producing lightweight composite materials developed by the National Institute of Standards and Technology (NIST; Gaithersburg, MD) could improve process control and eliminate the large or intrusive sensors called for by other techniques. The monitor uses a high-index lead-oxide-doped glass fiber and an argon-ion laser to measure chemical reactions and fluid flow inside a mold as a composite changes from liquid to solid form.

In operation, 488-nm laser output launched into the fiber excites an area with radiation, either through the distal end or through an evanescent wave on the fiber, explains NIST`s Richard Parnas. Fluorescence propagates back to an imaging spectrograph. The same fiber can be used for fluorescence as well as near-IR monitoring. In evanescent mode, measurements from a 0.5-µm-thick annulus around the fiber are collected. In distal mode, a volume of a cubic millimeter at the end of the fiber can be monitored. Tests at Ford Motor Co. (Dearborn, MI) provided useful information for process and quality control, although further development is required to improve the sensor for use in specific commercial systems. NIST is interested in working with a manufacturer to commercially develo¥the device.

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