Patent ID: 7161687
Filing Date: 2007-01-09
Classification: G01B

Abstract:
1. Method of performing geometrical measurements on an object, comprising the steps of: illuminating the object with a light beam having a field distribution with substantially constant intensity, so as to obtain, past the object, a field distribution with discontinuity points in correspondence with points concerned by the measurement; submitting the beam past the object to a spatial optical filtering; detecting the filtered beam thereby generating an electrical signal representative of the intensity of the field associated with the filtered beam; and obtaining the value of a requested quantity by processing said electrical signal; characterized in that said spatial filtering is a band-pass filtering originating on a detection plane a continuous field distribution that is the sum of a plurality of functions which are identical to one another apart the sign, are centered exactly in correspondence with a discontinuity point and only depend on the characteristics of the band-pass filtering, said field distribution having an intensity exhibiting a pair of marked maxima separated by a minimum in correspondence with each discontinuity point, said processing of the electrical signal providing the position of said minimum relative to an axis of the measurement beam, wherein a spacing between said minima at said discontinuity points corresponds to a size of said object.