Method and apparatus for optically measuring, without contact, the granulometry of a cloud of particles or the roughness of a surface
US4927267A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Mar 21, 1989 |
| Grant date | May 22, 1990 |
| Priority date | — |
| Expiry date | Mar 21, 2009 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG01N15/0211
- WIPO fieldMeasurement
- WIPO sectorInstruments
Abstract
The invention relates to the measurement of the granulometry of a cloud of particles or of the roughness of a surface in real time and without contact, by means of an apparatus comprising: a convergent lens (9) adapted for forming a diffraction pattern of the cloud of particles or of the surface: multiplier means (10) adatped for multiplying this diffraction pattern, in intensity, by a function f(r) such that EQU A(r.sup.1.5 +Br.sub.o.sup.4)<f(r)<A (r.sup.4 +Br.sub.o.sup.4) with PA1 A=constant determined by calibration of the apparatus PA1 B=constant: o<B<0.1 PA1 r=distance measured in the focal plane of the lens with respect to the optical axis thereof, r.sub.o =maximum useful radius of the spatial filter, and means (11, 24) adapted for carrying out a reverse Fourier transform on the result of the above intensity multiplication, whose result forms the desired spectrum of the granulometry of the cloud of particles or the desired spectrum of the roughness of the surface.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.