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Item A confocal Fabry-Perot interferometer for use in LIDAR receivers(Montana State University - Bozeman, College of Engineering, 2009) Neal, Kerry Ann; Chairperson, Graduate Committee: Kevin S. RepaskyA Confoal Fabry-Perot (CFP) interferometer was modeled, designed, built, and characterized. The proposed use of the CFP is as a narrowband filter in the receiver of lidar (light detection and ranging) instruments. Currently, a CFP very similar to the one discussed herein is being used in the High Spectral Resolution Lidar (HSRL), but through this work, the CFP will be adaptable to any lidar receiver. The goal was to characterize the CFP for a variety of parameter spaces that would be of interest to those using the CFP in a lidar receiver. These parameters include how the CFP performs with large diameter multi-spatial mode beams, large off-axis incoming angles, and large waist sizes at the center of the CFP. The modeling revealed that spherical mirrors would be suitable for the experiment. The modeling also demonstrated that angles up to 100 mrad are accepted into the CFP and waist sizes of at least 200 microns in the center of the CFP are useable. The characterization of the CFP was achieved with two experiments. The quality of performance of the CFP was expressed through measurements of finesse and transmission through the CFP for each parameter tested. The results of the experiments showed that the CFP performs optimally when nominally mode-matched or when collimated light is sent into the CFP. Also, the finesse of the CFP drops substantially as a function of the incoming waist size at first and then levels off at a fairly high finesse of around 100, which is a result that deviates from theory.Item Confocal Fabry-Perot interferometer based high spectral resolution LIDAR(Montana State University - Bozeman, College of Engineering, 2012) Hoffman, David Swick; Chairperson, Graduate Committee: Kevin S. Repasky.A high spectral resolution lidar (HSRL), which has been developed at Montana State University, utilizes a confocal Fabry-Perot interferometer (CFP) to separate aerosol and molecular lidar returns for the purpose of atmospheric aerosol observation. The CFP is actively frequency locked to the laser-transmitter via a novel frequency modulation based technique. 532 nm second harmonic light from a frequency doubled Nd:YAG injectionseeded, pulsed laser is directed vertically into the atmosphere. Light backscattered by the atmosphere is collected using a commercial Schmidt-Cassegrain telescope. The secondharmonic return signal is mode matched into a tunable CFP interferometer with a free spectral range of 7.5 GHz and a finesse of 50.7 (312) at 532 nm (1064 nm) placed in the optical receiver for spectrally filtering the molecular and aerosol return signals. The light transmitted through the CFP is used to monitor the aerosol return signal while the light reflected by the CFP is used to monitor the molecular return signal. Data collected with the HSRL are presented and inversion results are compared to those from a co-located solar radiometer, demonstrating the successful operation of the instrument. The HSRL presented in this dissertation provides an important means to study atmospheric aerosols, which are the largest source of uncertainty in current global climate models. Additionally, the novel frequency locking technique allows for the future development of multi-wavelength HSRL instruments, and the robustness of the frequency locked optical filter allows for the deployment of future air and space based HSRL instruments.