Solving the inverse problem for coarse-mode aerosol particle morphology with digital holography

Area of Science:

• Atmospheric science
• Optical physics
• Particle characterization

Background:

• Coarse mode atmospheric aerosol particles are prevalent in diverse environments.
• Accurate morphology characterization is crucial for understanding aerosol impacts on solar radiative forcing.
• Elastic light scattering is a common but limited method for inferring particle morphology.

Purpose of the Study:

• To address the non-uniqueness of particle morphology inference from scattering data (the inverse problem).
• To demonstrate a novel method for unique aerosol particle characterization.
• To enhance the understanding of aerosol-particle interactions with solar radiation.

Main Methods:

• Utilizing digital holography to capture wave-phase information.
• Applying spatial filtering techniques to holographic measurements.
• Analyzing scattering patterns from free-flowing aerosol particles.

Main Results:

• Digital holography successfully encodes wave-phase information.
• Spatial filtering resolves ambiguities in scattering pattern interpretation.
• A unique association between scattering patterns and particle properties (size, shape, orientation) is established.

Conclusions:

• Digital holography and spatial filtering effectively solve the inverse problem for aerosol morphology.
• This technique enables precise characterization of free-flowing aerosol particles.
• The findings advance the accurate assessment of aerosol effects on climate.