SBIR-STTR Award

Airborne measurements of cloud particle size, shape, and optical properties such as extinction cross-section are critical for validating satellite remote sensing measurements and weather and climate models. To address the current and future needs of the scientific community making and using these measurements, we propose a multispectral single-particle holographic imaging system which offers several advantages over current techniques. Our approach exploits a novel property of holographic imaging to directly calculate extinction cross-section at multiple wavelengths. Single-particle holographic measurements avoid the computationally expensive processing required by other holographic instruments. The overall project objective is the development of a new instrument capable of imaging cloud droplets and ice crystals and performing spectrally resolved cloud extinction measurements. Here in Phase I, to de-risk the overall project, we propose the development and testing of a simplified breadboard optical system focusing on holographic measurements at a single wavelength with flowing particles to verify the performance of the instrument using several particle standards of known shapes, including those mimicking cloud particles in a laboratory setting. Potential NASA Applications (Limit 1500 characters, approximately 150 words): This project would be highly beneficial to NASA ESD to enhance the characterization of 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 remote sensing observations and model results, employing identical wavelengths for its imaging and extinction measurements as are used on CALIOP and other LIDAR systems, including those deployed on NASA's airborne science fleet. Potential Non-NASA Applications (Limit 1500 characters, approximately 150 words): The proposed instrument would be invaluable to other entities performing airborne cloud measurements including DOE, NCAR, NOAA, and NSF domestically and NRC (CA), FAAM (UK), SAFIRE (FR) DLR (DE), and others internationally. Future conversion of this technique to a ground-based instrument for characterizing coarse mode aerosol would have broad applications beyond atmospheric science. Duration: 6

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