Purpose of this study was to develop a measurement system by which orientation, length and number of fibers in composite materials can be investigated. Mixture of carbon fibers and polyester resin were pressed into a thin specimen. The digitized image was processed by such procedures as image enhancement, thresholding, noise cleaning and thinning. From the data cross-point and end-point of individual fibers identified by utilizing proper masks and designated chain-code from the end point. At the cross point, the chain-code of separated fibers were obtained and compared to determine the most well-matched chain-code of the continuous fiber. From the chain-codes of all length and orientation of individual fibers were calculated along with the number of fibers. In order to represent the state of fiber orientation of the specimen enspected, orientation tensor was calculated from the chain-code obtained. To include the influence of the fiber length on orientation tensor, a new orientation tensor reflecting the effect of fiber length was defined and determined for the specimen. The newly introduced orientation tensor was shown to be more proper for characterization of fiber orientation of a composite material which contains short fibers of different length.
