Water vapor density is an essential climate parameter that influences atmosphere conditions and contributes to atmospheric dynamics. Existing sensing instrumentation for continuous monitoring of water vapor profiles in the atmosphere are limited by excessive size and weight, spatial resolution limitations, cost, eye-safety, and ability to simultaneously measure near and far-ranges. Areté proposes to adapt a newly developed continuous wave (CW) scanning lidar technology for Differential Absorption Lidar (DiAL) water vapor profiling that will address these challenges. Aretéâs patented CW scanning lidar technology operates by rapidly scanning a CW laser in a circular or conical scan pattern and imaging the returned light that is also received through the scanning system. The path of scattered light that returns to the scanner lags the scanner direction by an angle that is proportional to the distance to a scattering volume as well as the scanner rotation rate. Pixel coordinates of the imaged light determine the range and direction to the scattering volume. Areté is proposing to adapt an existing lidar system to make differential absorption lidar measurements possible by developing and integrating critical subcomponents. When signals are accumulated around a conical scan, vertical water vapor profiles will be determined with a laser that have 25 times greater average power than can be achieved with 0.5% duty cycle pulsed lasers used in state-of- the-art DiAL lasers. This increased optical power permits a much smaller receiver aperture which will scale the overall sensor volume to be less than a 10th the size of currently available sensors having comparable performance. The Phase-I effort will suppress solar background and improve sensitivity by integrating a new quantum imaging system (QIS) camera that has recently come to market, developing a novel spectral filtering device, and implementing an imaging enhancement component. In Phase-I, we will develop an 828nm laser source for testing purposes and will measure Rayleigh backscattering. The full demonstration of water vapor sensing will be achieved during Phase-II after upgrading the laser system to provide the two stabilized laser wavelengths and maturing the overall sensor controls. Water vapor profiling is sought for both operational forecasting measurements and for climate and environmental sciences. Radiosonde sensing is currently used to provide meteorological data for weather forecasting, but at great expense for relatively sparse data sets. Remote sensing measurements could dramatically reduce the requirement for radiosonde deployment and the related operational expenses while improving the quality of the data available and the accuracy of forecasts. High resolution water vapor data at specific cloud and weather features would improve our ability to refine climate modeling accuracy. Our technology is expected to make measurement campaigns for scientific studies more affordable. Water vapor sensing has additional applications for computing distortions to Radar systems that result from water-vapor dependent refractive variations and potentially for agricultural applications. Aside from the specific application of water vapor profiling, there is an objective to mature the CW scanning lidar technology which has broad ranging applications for sensing distributed media and hard targets. There is a need for detecting low-elevation drones and aerosol plumes where radar systems have degraded signals from ground clutter. Component development and commercialization of the technology for any one application will lower the barriers for transition for any of the other applications. Commercial viability of any of the applications will be increased if applications in multiple areas can be develo
