EVANESCENT-WAVE SPECTROSCOPY AS AN INTERFACE PROBE

Intrinsic silica fibre optic sensors were prepared using a hydrofluoric acid etch technique. The fibre optic sensors were coupled to an acoustic-optic tunable filter spectrometer for rapid data collection. The sensors were used to detect the presence of chemical species within the 10 mu m region of the glass/chemical interface by evanescent wave infrared spectroscopy in the near infrared spectral region. The room temperature cure of an epoxy diamine system was followed as a function of time. In addition, application of a chemical sizing to the glass fibre was detected, and the absorbance was a function of coating thickness, the refractive index and the quality of the coating. Immersion of the size-coated fibre in chloroform demonstrated the sensor capability to detect chemical species outside the size coating. Application of the sensor for interface optimisation in glass reinforced polymer composites is discussed.