ON THE MEASUREMENTS OF PARTICLES BY IMAGING METHODS - THEORETICAL ANDEXPERIMENTAL ASPECTS

Imaging techniques in particle sizing have always been important. Neve rtheless, owing to the progress in CCD cameras, these techniques have found new potential which strongly depends on the capability to descri be the image formation. Based on a combination of the generalized Lore nz-Mie theory and the diffraction theory, the image characteristics ar e described, taking into account the beam size, particle location, dir ection of observation and collecting optics characteristics. In the ca se of forward detection, a finite coherence is introduced and the resu lts are compared with those obtained by a convolution approach, with t he point spread function assumed to be Gaussian. Then some experimenta l results are displayed which underline the improvement achieved in pa rticle size measurement.