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A Laser Multi‐focus System for the Measurement of Particle Size, velocity and refractive index
Author(s) -
Nakatani Noboru,
Kohri Shigetoshi,
Yamada Tomoharu,
Sakabe Toshiya
Publication year - 1989
Publication title -
particle and particle systems characterization
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.877
H-Index - 56
eISSN - 1521-4117
pISSN - 0934-0866
DOI - 10.1002/ppsc.19890060110
Subject(s) - optics , refractive index , interference (communication) , laser , diffraction , focus (optics) , intensity (physics) , doppler effect , beam (structure) , grating , phase (matter) , materials science , particle (ecology) , physics , astronomy , engineering , oceanography , quantum mechanics , geology , channel (broadcasting) , electrical engineering
A laser multi‐focus velocimeter (LMFV) for measuring particle diameter, velocity and refractive index simultaneously is described. A phase diffraction grating with pulse width modulation is used to obtain several focal points with almost equal intensity and to construct the optical system. The fringes of the LMFV using multi‐beam interference have a sharper intensity distribution and wider period than those of a laser Doppler velocimeter using two‐beam interference. Therefore, the LMFV makes it possible to measure high velocities and large particle diameters with high accuracy. The validity of the method was confirmed theoretically and experimentally.