Optical techniques for determination of the state of cure of epoxy-resin-based systems

W. Craig Michie; Graham Thursby; Walter Johnstone; Brian Culshaw

doi:10.1117/12.141316

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26 March 1993 Optical techniques for determination of the state of cure of epoxy-resin-based systems

W. Craig Michie, Graham Thursby, Walter Johnstone, Brian Culshaw

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Proceedings Volume 1798, Fiber Optic Smart Structures and Skins V; (1993) https://doi.org/10.1117/12.141316
Event: Fibers '92, 1992, Boston, MA, United States

Abstract

Determination of the state of cure of epoxy resin based systems is of considerable interest to manufacturers of large carbon fiber reinforced plastic and glass reinforced plastic structures. Optical methods designed to indicate the cure state have been developed using a loss mechanism which is a function of the refractive index of the curing system. Such techniques are however subject to corruption from losses arising from other influences and consequently are limited in their measurement resolution. In this paper, two techniques which are able to provide a high degree of accuracy of measurement of refractive index are investigated as a means of performing cure measurements. The methods investigated involve the interaction of the evanescent field of a side polished optical fiber with an overlay waveguide or a surface plasmon. Coupling between the fiber and the overlay waveguide (or plasmon) is strongly influenced by the refractive index of the bulk superstrate above the overlay (in this case the curing resin system). Both sensing schemes are self referencing and are not influenced by loss.

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W. Craig Michie, Graham Thursby, Walter Johnstone, and Brian Culshaw "Optical techniques for determination of the state of cure of epoxy-resin-based systems", Proc. SPIE 1798, Fiber Optic Smart Structures and Skins V, (26 March 1993); https://doi.org/10.1117/12.141316

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