Digital Holography: A New View of Aerosols

Matt Berg

Kansas State University

March 27, 2026

Abstract

Aerosols—microscopic particulate matter suspended in gas—are ubiquitous. They include dust in a sunbeam, pollen in the air, soot in a flame, and the droplets or ice that form a cloud. Knowledge of aerosol properties, such as particle shape, size, and composition, is critical in many areas. Perhaps the most consequential are atmospheric aerosols and their effect on Earth's energy budget via radiative forcing, sunlight absorption, and scattering. Aerosols also act as nuclei for cloud droplets and ice, and they impact human health, e.g., consider allergens, viruses, and even suspended microplastics. Because particles often cannot be collected for physical analysis, we must infer their properties using contact-free methods. The conventional approach involves scattering light from particles to estimate their characteristics; however, there is no unique relationship between the pattern of scattered light and specific particle properties. We have pursued an alternative: digital holography, a coherent imaging method. By obtaining contact-free images, we avoid the ambiguities of conventional light scattering and can study aerosols at an unprecedented level of detail. This talk will review the fundamentals of digital holography, present some of our results imaging aerosol particles, and describe future directions for our work.