Measurement of Dispersion and Particle Size Distribution

Several methods may be applied for measuring the particle size distribution and these are summarized below. 

Three main attachments to the optical microscope are possible  

Differential interference contrast (DIC) This gives a better contrast than the phase contrast method. It utilizes a phase difference to improve contrast but the separation and recombination of a light beam into two beams is accomplished by prisms. DIC generates interference colors and the contrast effects indicate the refractive index difference between the particle and the medium. 

Polarized light microscopy This illuminates the sample with linearly or circularly polarized light, either in a reflection or transmission mode. One polarizing element, located below the stage of the microscope, converts the illumination to polarized light. The second polarizer is located between the objective and the ocular and is used to detect polarized light 

SEM can show particle topography by scanning a very narrowly focused beam across the particle surface. The electron beam is directed normally or obliquely at the surface. The backscattered or secondary electrons are detected in a raster pattern and 

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