Large-area, high-resolution image analysis of composite materials

An image analysis system based on a small network of parallel processors hosted within a PC has been developed to measure the orientations of glass and carbon fibres in a polymer matrix from a polished section using optical microscopy. A computer-controlled XY translation stage is used to scan a large sample area (mm × mm), at a high magnification to minimize measurement errors. The distance that the stage moves between adjacent image frames is accurately measured allowing partial images at the edges of image frames to be reconstructed and so produce a continuous area. By removing a small amount of material from the sample by polishing and rescanning the same sample area, data from a number of serial sections can be obtained. Pattern matching is then used to correlate the fibre images from each section, allowing full three-dimensional orientation data to be extracted, overcoming the limitations of measurements from a single, two-dimensional section plane.