Optical fibre grating refractometers for resin cure monitoring

The use of fibre grating refractometers as a means of monitoring the cure of a UV- cured epoxy resin is presented. The wavelength shift of the attenuation bands of a long period grating and the spectral response of a tilted fibre Bragg grating sensor were measured simultaneously during the cure of the resin and compared with measurements made using a fibre optic Fresnel- based refractometer. The results showed a good correlation ( 6 x 10(-3) rius) and illustrate the potential of the techniques for non-invasive composite material cure monitoring.