A DIRECT DETERMINATION OF FRACTAL DIMENSION OF FRACTURE SURFACES USING SCANNING ELECTRON-MICROSCOPY AND STEREOSCOPY

A rapid and accurate method of measuring fractal dimension of a fractured surface is described. The method uses a stereo pair of photomicrographs taken in a scanning electron microscope and digitized for computer analysis. The computer can automatically compare the offset at many places in the two images and calculate their height on the basis of the parallax angle. The sum of the area of all planes formed by an array of three-dimensional points is an approximation of the true surface area. The scale can be varied both in the microscope and in the computer; therefore, a fractal dimension can be calculated. Unlike previous methods, this one is direct and gave results intermediate between two prior indirect measurements.