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Item Opto-mechanical design and analysis for coherent active imaging(Montana State University - Bozeman, College of Engineering, 2022) Neeley, Jaime Branson; Co-chairs, Graduate Committee: Wm. Randall Babbitt and Joseph A. ShawThe objective of this thesis project was to design a monostatic lidar transmit (Tx) and receive (Rx) opto-mechanical apparatus for remote sensing at a variable range of 50 m - 500 m. The scope of this project begins from the fiber output of a pre-designed Frequency-Modulated Continuous Wave (FMCW) lidar system. After design criteria for the lidar module are given, the optical and mechanical design is presented, opto-mechanical tolerancing is presented, and assembly, alignment, and testing procedures are covered as well. This thesis shows that the required design criteria of diffraction-limited optical performance was achieved while accounting for predictable manufacturing and assembly errors modeled using a Monte Carlo tolerance analysis. Furthermore, this thesis shows that the modeled and measured optical performance results were in good agreement and recommendations are given for improvements for the next-generation revision of the lidar Tx/Rx module.Item Using sparse coding as a preprocessing technique for insect detection in pulsed LIDAR data(Montana State University - Bozeman, College of Engineering, 2022) Zsidisin, Connor Reece; Chairperson, Graduate Committee: Brad WhitakerThis research proposes using sparse coding as a preprocessing technique on insect lidar based data. This preprocessing technique will be used in conjunction with the Adaptive Boosting (AdaBoost), Random UnderSampling Boosting (RUSBoost), and neural network algorithms to automatically detect insects. The project aims to increase the effectiveness of these algorithms by using new images created by sparse coding. The K-Singular Value Decomposition (KSVD) algorithm will be used to train a dictionary on images that contain the majority class (non-insects). This trained dictionary will be used along with Orthogonal Matching Pursuit (OMP) to reconstruct all lidar images. The difference between the original image and the reconstructed image will be taken and processed by the feature extraction function and then used to train and test the models. Using a complete and an overcomplete dictionary our results show that the algorithms are able to detect insects at a higher rate. Using an overcomplete dictionary we are able to classify 93.18% of insect containing images in the testing dataset. Using the complete dictionary we were able to maintain 99.70% of non-insect images while increasing the percentage of insects classified to 84.09%.Item Diode-laser-based high spectral resolution LIDAR(Montana State University - Bozeman, College of Engineering, 2021) Colberg, Luke Stewart; Chairperson, Graduate Committee: Kevin S. RepaskyThis thesis describes the design, construction, and testing of a high spectral resolution lidar (HSRL) as a part of a combined HSRL and differential absorption lidar (DIAL) system. The combined HSRL and DIAL instrument is constructed using the MicroPulse DIAL (MPD) architecture and uses distributed Bragg reflector lasers. The MPD architecture is unique because it is eye-safe and cost-effective; therefore, it is ideal for creating a network of ground-based lidars. This instrument is designed for thermodynamic profiling of the lower troposphere. A network of these instruments would be helpful for wide-scale atmospheric monitoring for weather forecasting and climate science. The purpose of the HSRL is to retrieve the optical properties of aerosols in the lower troposphere. The HSRL uses the DIAL offline laser, which has a wavelength of 770.1085 nm, and a potassium vapor cell as the spectral filter. The data retrieved from the HSRL provides the aerosol backscatter coefficient and the backscatter ratio up to an altitude of 7 km during nighttime operation and 5 km during daytime operation. The time resolution for these measurements is 5 minutes, and the range resolution is 150 m. These aerosol optical properties are valuable for aerosol studies and climate modeling; aerosols introduce the most significant degree of uncertainty in modeling the heat flux of the atmosphere. Additionally, these aerosol optical properties can be used to find the planetary boundary layer height (PBLH). The planetary boundary layer controls the exchange of heat, water vapor, aerosols, and momentum between the surface and the atmosphere. It has been demonstrated that the PBLH strongly affects turbulent mixing, convective transport, and cloud entrainment, which makes the PBLH an important parameter for weather forecasting and climate modeling. Despite its significance in atmospheric science, there is no standard method for defining the PBLH. A retrieval method for finding the daytime PBLH using HSRL data is proposed, and data comparisons to radiosonde PBLH retrievals are provided. The algorithm shows a good agreement with the radiosonde retrievals for conditions with a well-behaved boundary layer.Item Machine learning pipeline for rare-event detection in synthetic-aperture radar and LIDAR data(Montana State University - Bozeman, College of Engineering, 2021) Scofield, Trey Palmer; Chairperson, Graduate Committee: Brad WhitakerIn this work, we develop a machine learning pipeline to autonomously classify synthetic aperture radar (SAR) and lidar data in rare-event, remote sensing applications. Here, we are predicting the presence of volcanoes on the surface of Venus, fish in Yellowstone Lake, and select marine-life in the Gulf of Mexico. Given the efficiency of collecting SAR images in space and airborne lidar geographical surveys, the size of the datasets are immense. Immense training data is desirable for machine learning models; however, a large majority of the data we are using do not contain volcanoes or fish, respectively. Thus, the machine learning models must be formulated in such a way to place a high emphasis on the minority, target classes. The developed pipeline includes data preprocessing, unsupervised clustering, feature extraction, and classification. For each collection of data, sub-images are initially fed through the pipeline to capture fine detail characteristics until they are mapped back to their original image to identify overall region behavior and the location of the target class(es). For both sub-images and original images, results were quantified and the most effective algorithm combinations and parameters were assigned. In this analysis, we determined the classification results are not sufficient enough to propel a completely autonomous system, rather, some manual observing of the data will need to be performed. Nonetheless, the pipeline serves as an effective tool to reduce costs associated with electronic storage and transmission of the data, as well as human labor in manually inspecting the data. It does this by removing a majority of the unimportant, non-target data in some cases while successfully retaining a high percentage of the important images.Item Results of a micro pulse differential absorption LIDAR for temperature profiling and analysis code(Montana State University - Bozeman, College of Engineering, 2021) Cruikshank, Owen Daniel; Chairperson, Graduate Committee: Kevin S. RepaskyThermodynamic profiling of the lower troposphere is necessary for the study of weather and climate. The micropulse DIAL (differential absorption lidar), or MPD, presented here is designed to fill the need. The MPD is eye-safe and can run autonomously for continuous measurements compared to technologies with similar measurement capabilities like Raman lidar. Using a temperature-sensitive absorption line of O 2, the MPD system can measure the absorption of O 2 in the lower troposphere as a function of range and convert that measurement to temperature as a function of range. This process relies on a perturbative correction to the absorption retrieval to account for the fact that the O 2 absorption spectral linewidth is similar to the molecular Rayleigh scattering linewidth. An ancillary measurement of the ratio of aerosol backscatter to molecular backscatter is required for the correction. The integrated high spectral resolution lidar (HSRL) uses a heated potassium vapor notch filter to make the aerosol-to-molecular ratio measurement. An analysis program in MATLAB was written to take in raw lidar data and produce a temperature product of range and time. Results presented from a campaign at the Atmospheric Radiation Measurements program Southern Great Plains site in Oklahoma in spring 2019 show temperature comparisons with radiosonde measurements with a mean difference between radiosonde and MPD measurements of -1.1K and a standard deviation of 2.7 K. Further results from an instrument on the Montana State University campus in Bozeman and at the National Center for Atmospheric Research in Boulder, Colorado have shown that the MPD instrument can produce measurements autonomously for periods of weeks to months.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 Airborne LIDAR applications in freshwater lakes(Montana State University - Bozeman, College of Engineering, 2017) Roddewig, Michael Robbin; Chairperson, Graduate Committee: Joseph A. ShawIn this dissertation we demonstrate a novel, low-cost, compact airborne lidar designed for marine fisheries research. We discuss the details of our design, show its application to management of invasive lake trout (Salvelinus namaycush) in Yellowstone Lake, and mapping of the lidar attenuation coefficient in lake water. Results from 2015 and 2016 are presented, and we also report the lidar detection of underwater thermal vents in Yellowstone Lake.Item Scanning wing-beat-modulation LIDAR for insect studies(Montana State University - Bozeman, College of Engineering, 2017) Tauc, Martin Jan; Chairperson, Graduate Committee: Joseph A. ShawThe spatial distributions of flying insects are not well understood since most sampling methods - Malaise traps, sticky traps, vacuum traps, light traps - are not suited to documenting movements or changing distributions of various insects on short time scales. These methods also capture and kill the insects. To noninvasively monitor the spatial distributions of flying insects, we developed and implemented a scanning lidar system that measured wing-beat-modulation. Transmitting and receiving optics were mounted to a telescope that was attached to a scanning mount. As it scanned, the lidar collected and analyzed the light scattered from insect wings of various species. Mount position and pulse time-of-flight determined spatial location and spectral analysis of the backscattered light provided clues to insect identity. During one day of a four day field campaign at Grand Teton National Park in June of 2016, 76 'very likely' insects and 662 'somewhat likely' insects were detected, with a maximum range to the insect of 87:6m for 'very likely' insects.Item Two channel receiver design and implementation for a ground based micro-pulse differential absorption LIDAR (DIAL) instrument(Montana State University - Bozeman, College of Engineering, 2016) Moen, Drew Roland; Chairperson, Graduate Committee: Kevin S. RepaskyCurrent standard water vapor measurement techniques lack the required temporal and spatial resolution needed to further our understanding of the role of water vapor in the Earth's atmosphere. This thesis reports on the continued efforts to bring a cost-effective, autonomous, eye-safe, ground based, micro-pulse differential absorption lidar for the continuous measurement of water vapor into fruition. More specifically, the receiver for this instrument needs a dynamic range of measurement spanning from as close to the Earth's surface as possible, up through the troposphere. Previous reports on this system provide accurate backscatter measurement down to 2 km above the surface. A newly designed receiver has been modeled with the help of Zemax optical design software. It implements a 10% pickoff of the total received light into a second detection channel with a wider field of view. This channel utilizes a free space avalanche photodiode (APD) and has a full angle field of view of ~1 mrad. This channel (the near field) provides accurate backscatter measurement between 600 meters and 5 km in theory. The 90% channel utilizes a fiber coupled APD with a full angle field of view of ~200 microradians. This channel (the far field) has been shown to provide accurate backscatter measurements between 2 km and 12 km. While the near field channel has shown improvement to the overall system, the measured results appear to be accurate down to ~1 km. The results show continuous and autonomous operation with water vapor measurements in close agreement from both detection channels. Further comparisons with radio-sondes provide validation of the water vapor DIAL data product.Item Development of a singly-resonant optical parametric oscillator for carbon cycle science(Montana State University - Bozeman, College of Engineering, 2015) Jones, Briana Lynn; Chairperson, Graduate Committee: Kevin S. RepaskyThe human impact on the global carbon cycle is affecting the health of the environment by changing the balance between incoming and outgoing radiation as well as altering other geochemical cycles such as the nitrogen and water cycles. Although carbon dioxide makes up most of the greenhouse gas emissions, methane has a much greater impact on climate change due to its warming potential on a per molecule basis. Improved understanding of the spatial distribution of methane is necessary to quantify the anthropogenic impacts and mitigate future damage. A differential absorption lidar (DIAL) is proposed for spatially mapping methane concentrations. The system requires a laser transmitter that can produce over 3 mJ of pulse energy with a repetition rate of 1 kHz and output wavelength of 1.654 micron as well as a narrow linewidth on the order of 3 MHz. Modeling predicts that a system with these specifications can achieve measurement error of less than 2% relative to ambient levels of methane. Laser sources with these specifications are not commercially available, and the goal of this work is to evaluate the potential for a singly-resonant optical parametric oscillator (OPO) for the DIAL laser transmitter. The OPO is based on large-aperture periodically-poled magnesium-oxide-doped lithium niobate as the nonlinear optical material. Results from the OPO indicate that energies on the order of 1 mJ are possible with the experimental setup presented when operating at 20 Hz repetition rate. The OPO produced a linewidth of 10.5 GHz, measured on a system with resolution of 6.6 GHz. Future work includes optimization of the OPO to increase the output energy from the system to 3 mJ by improving mode-matching into the cavity and increasing the energy into the system. Additionally a method to precisely measure the linewidth of the OPO output is necessary as well as a pump laser that operates at 1 kHz to test the performance of the OPO at 1 kHz. The initial results show promise for the use of the OPO as the DIAL laser transmitter and with improvements, the OPO should meet the requirements for the DIAL system.