Theses and Dissertations at Montana State University (MSU)
Permanent URI for this collectionhttps://scholarworks.montana.edu/handle/1/733
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Item Phase gradient averaging for holographic aperture LIDAR in the presence of turbulence(Montana State University - Bozeman, College of Engineering, 2017) Blaszczyk, Christopher Ross; Chairperson, Graduate Committee: Joseph A. ShawThe resolution of an image is dictated by the size and quality of the imaging system. The imaging system has a physical limit to the resolution dictated by the diffraction limited resolution. This limit can be improved by making the aperture larger on the imaging system. The increase in the physical aperture size can only be practical to a certain extent. However, to get beyond these physical constraints it is possible to use synthetic aperture methods to allow for the aperture to appear to be increased. Synthetic apertures are created by adding apertures coherently together to create a larger aperture that increases the diffraction limited resolution. To sum the aperture coherently the phase information needs to be available. One way to have access to the phase information is to capture the image as hologram. These holograms are captured by using a coherent light source with a reference beam to create an interference pattern that contains the phase information of the target. Holographic apertures can be used in a synthetic aperture method called Holographic Aperture Lidar (HAL). A problem that can arise while capturing images is turbulence in the atmosphere. Turbulence is a change in the index of refraction caused by a change in the temperature and pressure of the atmosphere. This causes the phase of the light to distort dynamically as it propagates making HAL imaging difficult. This thesis will cover a method to restore the original phase of the signal that has passed through turbulence so that it can be used in digital holography and HAL. This method uses averaging of the phase gradient to remove the dynamic turbulence and keep the phase information of the static target. The improvements observed in actual experiments were small, but the basics of the method worked, and the reason for only small improvement are discussed.Item Instrumentation requirements and design of a facility for turbulent natural convection studies(Montana State University - Bozeman, College of Engineering, 1983) Pracht, David AllynItem Measurements of the intensity of concentration turbulence in inline motionless mixing systems(Montana State University - Bozeman, College of Engineering, 1977) McCready, Arthur KirkItem The radial pressure gradient for turbulent flow in smooth pipes(Montana State University - Bozeman, College of Engineering, 1971) Greene, Charles WillisItem Turbulence structure in smooth and rough pipes(Montana State University - Bozeman, College of Engineering, 1970) Powe, Ralph EdwardItem Wall roughness characterization in turbulent flow(Montana State University - Bozeman, College of Engineering, 1972) Slanina, Gary StephenItem The deposition of particulates in turbulent pipe flow(Montana State University - Bozeman, College of Engineering, 1976) Sande, Charles KennethItem Turbulence modeling of solidification process during continuous casting(Montana State University - Bozeman, College of Engineering, 2002) Mahajan, AnuragItem Velocity profile measurements of laminar, turbulent and laminar pulsating flow(Montana State University - Bozeman, College of Engineering, 1967) Mower, Michael GrahamItem Fully-developed turbulent flow in smooth and rough-walled pipe(Montana State University - Bozeman, College of Engineering, 1969) Gow, John Leonard