Device for the optical measurement of the edge to edge dimension of an object

摘要

Optical device forms a magnified image of the object to be measured. A photosensitive member constituted by a sequence of photosensitive elements is arranged in the image plane. An analog-digital converter is connected to the photosensitive member and a digital processing circuit performs a discrete Fourier transformation and determines the value N of the first minimum of the spectrum obtained or the mean variation N between minima. The sought dimension L of the object to be measured is obtained by the relation L=X/N, in which X is a parameter defined by the operating conditions.