Scholarship & Research
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Item Digitally automated alignment of a phase-shifting point diffraction interferometer(Montana State University - Bozeman, College of Engineering, 2020) Field, Nathaniel James; Chairperson, Graduate Committee: Joseph A. ShawReal-time sensing of wavefront error in laser instruments is an exceptionally useful tool for fine-tuning of laser systems during fabrication. Measurement and correction for potential wavefront aberrations are especially important for high-energy laser system applications, such as defense and industrial manufacturing. The self-referencing Mach-Zehnder interferometer and the Shack-Hartmann wavefront sensor are two common methods used to achieve real-time wavefront aberration measurements for laser system output quality; however, the former requires a precise and arduous alignment procedure for each operation and the latter exchanges spatial resolution for phase resolution and is highly sensitive to global tilt. The use of electronically controlled spatial light modulators has been shown as a method of quickly retrieving wavefront reconstructions from phase-shifting point diffraction interferometers. In this paper, the development of an algorithm that automates the selection of the point diffractor position and size was added to the phase-shifting point diffraction method with a purely reflective spatial light modulator. Computer simulations and laboratory tests were conducted as proofs of concept using a few simple optical elements. The results of these simulations and lab measurements show promise for continually automated alignment of a point diffraction interferometer to greatly reduce alignment time and almost entirely remove sensitivity to global tilt. With further development, this method can be applied to increase the efficiency of a wide variety of optical system measurement scenarios.Item Optimization of error correcting codes in FPGA fabric onboard cube satellites(Montana State University - Bozeman, College of Engineering, 2019) Tamke, Skylar Anthony; Chairperson, Graduate Committee: Brock LaMeresThe harmful effects of radiation on electronics in space is a difficult problem for the aerospace industry. Radiation can cause faults in electronics systems like memory corruption or logic flips. One possible solution to combat these effects is to use FPGAs with radiation mitigation techniques. The following Masters of Science thesis details the design and testing of a radiation tolerant computing system at MSU. The computer is implemented on a field programmable gate array (FPGA), the reconfigurable nature of FPGAs allows for novel fault mitigation techniques on commercial devices. Some common fault mitigation techniques involve triple modular redundancy, memory scrubbing, and error correction codes which when paired with the partial reconfiguration. Our radiation tolerant computer has been in development for over a decade at MSU and is continuously being developed to expand its radiation mitigation techniques. This thesis will discuss the benefits of adding error correcting codes to the ever developing radiation tolerant computing system. Error correcting codes have been around since the late 1940's when Richard Hamming decided that the Bell computers he did his work on could automate their own error correcting capabilities. Since then a variety of error correcting codes have been developed for use in different situations. This thesis will cover several popular error correcting method for RF communication and look at using them in memory in our radiation tolerant computing system.