Method for measuring mean particle size of the bulk powder using speckle patterns

Area of Science:

• Optical Metrology
• Materials Science
• Particle Characterization

Background:

• Accurate measurement of fine particle size in bulk is crucial for material properties.
• Traditional methods can be complex or require extensive sample preparation.

Purpose of the Study:

• To develop a straightforward method for determining the surface-area mean diameter of fine particles in a bulk state.
• To utilize optical correlation properties of speckle patterns for particle size measurement.

Main Methods:

• Generating two coherent speckle patterns from the same powder surface region.
• Employing double-exposure speckle photography and cross-correlation analysis.
• Relating speckle pattern correlation to particle size and illumination angles.

Main Results:

• A direct relationship was found between speckle pattern correlation and the surface-area mean diameter of particles.
• The method's accuracy is influenced by the incidence angle difference between illuminations.
• The technique demonstrated simplicity in measurement procedures and minimal sample pretreatment.

Conclusions:

• The developed speckle correlation method offers a simple and effective way to measure mean particle size in bulk.
• This technique holds potential for various industrial applications requiring rapid powder characterization.
• Further research can optimize the method for different particle types and conditions.