Improved Different Absorption LIDAR System for Measurement of Atmospheric Water Vapor and Temperature

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This Small Business Innovation Research Phase I project will address the feasibility of a turn-key Differential Absorption LIDAR (DIAL) system for the measurement of atmospheric water vapor and temperature profiles. Advanced atmospheric models require spatially resolved measurements of humidity and temperature at high altitude where existing measurement techniques are inaccurate. To address these needs, the proposed system combines commercially available laser sources to generate well controlled, narrow line width pulses that will allow remote measurement of water vapor concentration with a sensitivity of 0.5 mg/kg and temperatures to within 2 K. The system will be constructed from laser sources that are well developed and have already been engineered for high reliability. Wavelength control will be provided by a single-mode diode laser amplified to suitable pulse energies. Characterizing the amplified diode laser pulses will be the key research objective in Phase I. Use of a pulse-amplified cw laser will result in improved frequency control that is essential for accurate measurement at the tropopause and lower stratosphere. Furthermore, by taking advantage of both the tunability and narrow line width of a single-mode diode laser, water absorption line ratios can be measured from which remote temperatures can be determined. The system will be compact, robust, have high wall-plug efficiency, and will operate safely in a look-down geometry.