METHOD AND APPARATUS FOR NON-CONTACT OPTICAL MEASUREMENT OF PARTICLE CLOUD GRANULOMETRY OR ROUGHNESS OF SURFACE

摘要

The invention relates to measuring, in real time and without contact, the particle size of a cloud of particles or the roughness of a surface, using an apparatus comprising: a converging lens 9 forming a diffraction pattern of the particle cloud or surface; multiplying means 10 multiplying, in intensity, this diffraction pattern by a function f ** (r) that: / P P A (r ** 1 **, ** 5 + Bro ** 4) = f (r) = A (r ** 4, + Bro ** 4) / P P with A = constant determined by calibration, / P P B = constant o = B = 0,1, / P P r = distance measured in the focal plane of the lens with respect to the optical axis thereof; / P P ro = maximum useful radius of the filter spatial; and means 11 performing, on the result of this multiplication, an inverse Fourier transform whose result constitutes the desired spectrum of particle size distribution or the desired spectrum of surface roughness. / P