An optical information procedure for characterizing the shape of fine particle images

摘要

In a search for a method for characterizing the shape of particle images using optical information processing procedures, the technique of Redman and Reid for optical character recognition has been modified to explore the structure of several particle images. In the Redman and Reid method the Fourier transform of the image is interrogated by a rotating disc from which a sector has been removed. The waveforms generated by the interrogation of the diffraction pattern is subjected to Fourier analysis. The spectrum of the waves is characteristic of the shape of the character to be studied. Using this system we have explored the diffraction pattern of rectangles and ellipses of different shape. We then measured the diffraction patterns for several irregular particle profiles and compared them to the frequency spectrum generated for the rectangles and ellipses. It is demonstrated that using this procedure it is possible to obtain a shape characteristic spectrum by direct optical processing procedures which enable a profile to be described in terms of an equivalent ellipse or rectangle.