Visible Infra-Red Double Extinction Measurements in Densely Laden Media, New Progress
Optical techniques for measurements of particle sizes and concentrations are usually limited to the investigation of low optical thickness media. For instance, in LDA-based systems, it is generally required, as a rule of thumb, that the control volume should not contain simultaneously more than one particle. Furthermore, the incoming beams to produce the optical probe and the outgoing scattered light must not be spoiled by the presence on the optical pathes of a too large amount of refractive index inhomogeneities. Another example is Malvern diffractometry (1,2, among many others). Recent developments in this technique, including multiple scattering corrections, permit to investigate media for which the transmittance is as small as 2% (3,4), corresponding to an optical thickness equal to 4. Although other progress are likely, optical thicknesses limitations are expected to be encountered in a near future (a dangerous statement indeed).
KeywordsOptical Thickness Coal Particle Glass Particle Dust Explosion Dense Spray
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