Holographic Cloud Particle Imager (HCPI)

The Department of Energy and the Atmospheric Radiation Measurement Climate Research Facility provides information needed for future climate projections, used by the Intergovernmental Panel on Climate Change and other policy-making activities. Current climate models include assumptions on the size and 3D spatial distribution of cloud particles. Existing cloud particle imagers allow for imaging only a cross- section of particles at a given time and location, leaving the third dimension of the cloud particle distribution unknown. The capabilities of present technology result in climate predictions and policy decisions based on models that have significant uncertainties. The overarching goal of this effort is to improve climate model predictions with measurements from a small, lightweight holographic cloud particle imager (HCPI) mounted on an unmanned aerial system (UAS). The HCPI provides data to improve upon current climate models by measuring the 3D cloud particle spatial and size distributions. The goal of this program is to miniaturize an HCPI, using recent advances in optics and photonics, and to decrease the holographic reconstruction time to allow for “real- time” data assessment. The Phase-1 effort designs an HCPI system, constructs a benchtop system, and develops the post-processing algorithm. Results from a benchtop system based on designs in the scientific literature will demonstrate the feasibility of the approach. For an in-line geometry of the HCPI design, a hologram is formed through the interference of the part of the beam that transmits through the volume and the parts of the beam that are scattered by cloud particles. The HCPI provides information about the entire 3D volume by applying post-processing algorithms on each recorded hologram. The Phase-2 effort focuses on constructing a manufacturable HCPI prototype for a UAS at a reasonable cost. A miniature holographic cloud particle imager is proposed to increase the accuracy of climate models and improve climate policy decisions. The device will be small enough to fly on an unmanned aerial system (UAS) for high volume, long-term sampling of clouds. Commercial Applications and Other Benefits: A commercialized holographic cloud particle imager that is small enough to be flown on a UAS could also be used for studying other processes that generate many small particles (i.e. atomization, impacts, and explosions). Intricate fluid flow and air flow measurements could also be made by imaging 3D volumes of tracer particles.