Phase profiles of transmitted light through glass-particle-dispersed epoxy-matrix composites

The phase profile of a transmitted laser beam through glass-particle-dispersed epoxy-matrix composites was measured using the interferometric measurement method. The effect of dispersed particles' on the light scattering behaviour of the composite was determined from the difference between the in-line and total light transmittance. The difference between the light transmittances increases with increase in the particle volume fraction and this result indicates that the glass particles are a major source of light scattering in the composite. The phase profile changes with the addition of glass particles; a higher particle volume fraction yields a larger phase profile distribution. This result demonstrates that the phase profile of the transmitted light is strongly correlated with the total amount of light scattering source in the composite. The measured phase delay becomes pronounced on increasing separation from the laser beam axis and this behaviour is explained by increase in the laser beam path in the composite caused by the light scattering.