Airborne measurements of cloud particle size, shape, and optical properties such as extinction cross-section are critical for furthering atmospheric science and advancing the use of satellite data to help understand the Earth system. The current generation of instruments cannot accurately characterize the shape and optical properties of particles smaller than 100 µm, especially in mixed-phase or glaciated conditions. We also lack tools for characterizing coarse mode aerosol, which are difficult to sample from aircraft, that can also have important atmospheric impacts. To address this shortcoming, we propose development of a holographic imaging system capable of single-particle or ensemble measurements depending on conditions and operator need. Benefits over current instrumentation include faster time resolution and better sampling statistics compared to existing holographic instruments, more detail regarding particle morphology compared to existing particle sizing and counting instruments, and better sampling characterization compared to imaging instruments. In addition, our technique will enable direct determination of extinction cross-section for individual particles under certain conditions, which will enable better measurements of aerosol and cloud extinction, especially for thin features such as sub-visible cirrus and aerosol layers. Potential NASA Applications (Limit 1500 characters, approximately 150 words): The project would be directly beneficial to NASA's Earth Science Division by enhancing capabilities to measure cloud microphysical properties. The instrument would be suitable for deployment on platforms including the DC-8, P-3, B-200, WB-57, and Global Hawk. The instrument is also well suited to validate satellite observations and model results, and will employ wavelengths measurements identical to those used on CALIOP and other LIDAR systems (532 and/or eventually 1064 nm), including those used on NASA's airborne science fleet. Potential Non-NASA Applications (Limit 1500 characters, approximately 150 words): The proposed instrument would be valuable to other entities performing airborne cloud measurements, including DOE, NOAA, and NSF in the US and NRC (CA), FAAM (UK), SAFIRE (FR), DLR (DE), and others internationally. Future conversion of the technique to a ground-based instrument for measuring coarse mode aerosol would have broader applications beyond atmospheric science (e.g., pollen detection). Duration: 24