Recent advancements in LiDAR for atmospheric applications have allowed measurements to reach higher altitudes and have increased temporal resolu- tion. Increased output power, larger apertures, and higher efficiency detec- tors have made this possible. The helium resonance fluorescence LiDAR has the capability to probe the metastable helium content in the thermosphere and exosphere (within 250 km-750 km), where helium (23S) is most abundant. Strategies have been employed to increase the output power of the He Li- DAR transmitter using fiber amplifier technology, increase the light gathering power of the receiver, and utilize detectors with higher quantum efficiencies at 1083 nm. A 45 W He resonance fluorescence LiDAR transmitter has been designed and fabricated, and is being tested in Urbana, IL, with plans for deployment at an astronomical observatory in the near future. The He reso- nance fluorescence LiDAR has the potential to further our understanding of upper atmosphere dynamics. It will provide insight into metastable helium, its temperature in the upper atmosphere, and atmospheric densities, which affect satellite drag, and possibly pave the way for new applications, such as guide star lasers. The technology may be applied from ground based, as well as satellite based, platforms for global measurement applications. This dissertation discusses the planned approach to detect the first LiDAR gener- ated resonantly fluoresced scattered He photon, details of the He resonance fluorescence LiDAR transmitter, and the simulations for the expected signal return.
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