We propose a nadir-pointing space-based Na Doppler resonance fluorescence LIDAR on board of the International Space Station (ISS). The science instrument goal is temperature and vertical wind measurements of the Earth Mesosphere Lower Thermosphere (MLT) 75-115 km region using atomic sodium as a tracer. Our instrument concept uses a high-energy laser transmitter at 589 nm and highly sensitive photon counting detectors that permit range-resolved atmospheric-sodium-temperature profiles. The atmospheric temperature is deduced from the linewidth of the resonant fluorescence from the atomic sodium vapor D2 line as measured by our tunable laser. We are pursuing high power laser architectures that permit limited day time sodium lidar observations with the help of a narrow bandpass etalon filter. We discuss technology, prototypes, risks and trades for two 589 nm wavelength laser architectures: 1) Raman laser 2) Sum Frequency Generation. Laser-induced saturation of atomic sodium in the MLT region affects both sodium density and temperature measurements. We discuss the saturation impact on the laser parameters, laser architecture and instrument trades. Off-nadir pointing from the ISS causes Doppler shifts that effect the sodium spectroscopy. We discuss laser wavelength locking, tuning and spectroscopic-line sampling strategy.
Michael A. Krainak, Anthony W. Yu, Steven X. Li, Yingxin Bai, Kenji Numata, Jeffrey R. Chen, Molly E. Fahey, Frankie Micalizzi, Oleg A. Konoplev, Diego Janches, Chester S. Gardner, and Graham R. Allan, "Progress on laser technology for proposed space-based sodium lidar," Proc. SPIE 10511, Solid State Lasers XXVII: Technology and Devices, 105111E (Presented at SPIE LASE: January 31, 2018; Published: 15 February 2018); https://doi.org/10.1117/12.2290471.
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Study of self-shadowing effect as a simple means to realize nanostructured thin films and layers with special attentions to birefringent obliquely deposited thin films and photo-luminescent porous silicon