Backscattering measurements of micron-sized spherical particles

Area of Science:

• Optical Physics
• Atmospheric Optics
• Particle Science

Background:

• Enhanced backscattering, responsible for the optical phenomenon known as glory, occurs at specific angles.
• Understanding light scattering is vital for fields like atmospheric optics and particle characterization.
• Previous studies indicate a strong theoretical dependence of backscattering on particle parameters.

Purpose of the Study:

• To design and build an apparatus for precise measurement of scattered light at angles characteristic of enhanced backscattering (180°±6°).
• To validate the apparatus using established methods like Fraunhofer diffraction and diffuse reflection.
• To experimentally investigate the relationship between particle properties and backscattering intensity.

Main Methods:

• Apparatus design and assembly for measuring scattered light near the backscattering direction (180°±6°).
• Calibration of the apparatus using Fraunhofer circular aperture diffraction, angle of incidence correction, and a diffuse reflector.
• Experimental measurements of light scattering from polystyrene latex spheres and water droplets.

Main Results:

• The developed apparatus successfully measured scattered light in the critical backscattering range.
• Experimental data from polystyrene spheres and water droplets showed good agreement with Mie theory predictions.
• Results demonstrated the high sensitivity of backscattering intensity to variations in particle size, refractive index, and shape.

Conclusions:

• The validated apparatus is suitable for studying enhanced backscattering phenomena.
• Experimental findings confirm the theoretical dependence of backscattering on particle parameters.
• The study provides valuable data for applications in particle scattering analysis, particle metrology, and LIDAR technology.