HOLOGRAPHIC CLOUD PARTICLE IMAGER (HCPI)

Current climate models have significant cloud-related uncertainties, due in part to the assumption that the spatial distribution of cloud particles is random; however, recent measurements have shown evidence that this is not always the case, and existing cloud particle imagers can only image a cross-section of particles per sample volume, leaving the third dimension of the cloud particle distribution unknown. The proposed effort will develop a device that can be mounted on an unmanned aerial system and measure the spatial distribution of particles in a cloud to provide a better understanding of their radiation transport properties, droplet collision and coalescence and droplet growth by condensation, thereby enabling more accurate climate models to be developed. A combination of in-line holography and cutting- edge graphics-processing-unit-based reconstruction and analysis allows for volumetric imaging of clouds in a reasonable amount of time. During Phase I, a benchtop version of the instrument was built and used to take holograms of resolution targets and moving aerosol particles. Reconstruction and analysis was executed on both a computer and a graphics processing unit to obtain speed benchmarks. During Phase II, a prototype was designed, built, and flown on a manned aircraft. Collected data is being analyzed for publication in an academic journal. Methods to transfer data to the user mid-flight were evaluated. The reconstruction and analysis codes were optimized for speed and benchmarked to determine the bottlenecks to target during Phase IIB. Finally, a prototype light enough to be mounted on an unmanned aerial system was completed. During the Phase IIB, the focus will be on commercial validation of the instrument on a test flight with a suite of commercial instruments and on developing commercial markets. The design will be optimized to significantly reduce the cost of the instrument with substitutions for expensive components (e.g., the pulsed nanosecond laser), and a lower-cost prototype will be designed and fabricated. Atmospheric measurement industry leaders will also be consulted on how to optimize the procurement and manufacturing process and partner with them to help commercialize the device in Phase III. In parallel, the analysis software will be refined to reduce processing time. The instrument has commercial potential for meteorological and environmental agencies around the world. In addition to meteorological applications, a pharmaceutical manufacturer and an aerosol spray nozzle manufacturer have expressed that the device has potential to compete with equipment currently used for characterization.