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The Electrochemical Noise Method (ENM) monitors the small potential and current fluctuations that occur naturally in electrochemical cells. It is the least intrusive of all electrochemical techniques in common use. This work uses the Electrochemical Noise Method to investigate the corrosion protection afforded by organic coatings. A parameter called Noise Resistance (Rn) is derived from an Ohm law relationship using the potential noise (Vn) and current noise (In) values. The noise on the current and potential data sets is calculated as the standard deviation value. The work is divided into three areas. The first looked at coating systems in the intact state on the substrate. In general this part of the work has corroborated previous work where Rn values of >l x 10^7 ohms-cm^2 indicated protection of the substrate, correlating with DC resistance values of the coating. The second area of work investigated scribed coatings on the substrate. An important property of organic anti-corrosive coatings is the ability to protect the substrate at a break in the coating. In the scribed work the level of protection afforded at exposed metal by the coating was related to the Noise Resistance value. The third area of this investigation looked at novel ENM techniques to investigate organic coatings. Detached intact coatings were examined in a “U” tube test cell that can be used to simulate different conditions that may be encountered in service. Also a new technique was devised for obtaining ENM data from corrosion cells, this does not require the two separate substrate elements necessary for the more established methodology. The new technique has been called the Single Substrate (SS) technique to reflect this useful property. The technique could be used for in-situ monitoring of structures and it could be adapted for investigation of other situations such as reinforcement bars in concrete

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This work does not limit itself to its title and touches on a number of related topics beyond it. Starting with the title, Polarization Aberrations of Optical Coatings, the immediate question that comes to mind is: what coatings? All coatings? Not all coatings, but just enough that a third person could take this information and apply it anywhere: to all coatings. The computational work-flow required to break-down the aberrations caused by polarizing events (3D vector forms of reflection and refraction) in dielectric and absorbing materials and for thick and thin films is presented. Therefore, it is completely general and of interest to the wide optics community. The example system is a Ritchey-Chrétien telescope. It looks very similar to a Cassegrain, but it is not. It has hyperbolic surfaces, which allows for more optical aberration corrections. A few modern systems that use this configuration are the Hubble Space Telescope and the Keck telescopes. This particular system is a follow-up on this publication, where an example Cassegrain with aluminum coatings is characterized, and I was asked to simply evaluate it at another wavelength. To my surprise, I found a number of issues which lead me to write a completely new, one-of-its-kind 3D polarization ray-tracing code. It can do purely geometrical ray-tracing with add-on the polarization analysis capability, and more importantly: it keeps your data at your fingertips while offering all the outstanding facilities of Mathematica. The ray-tracing code and its extensive library, which can do several advanced computations, is documented in the appendix. The coatings of the Ritchey-Chrétien induce a number of aberrations, primarily, but not limited to: tilt, defocus, astigmatism, and coma. I found those forms to exist in both aluminum and with a reflectance-enhancing dielectric quarter-wave multilayer coating over aluminum. The thickness of the film stack varies as function of position to present a quarter-wave of optical thickness to oblique rays. Most commercial optical software that I know cannot compute this. And the results are impressive: the scalar transmission, which is a measure of ray efficiency, was raised from 78% to 95%. This means that only 5% of the incident light is lost, assuming ideal coating interfaces. This is very advantageous, considering the application: coronagraphs for exoplanet detection. Exoplanets are very far away, and therefore efficient use of light is essential. I also created a ray! I call it Huygens' twin ray. It is credited to Christiaan Huygens, who postulated that points on a wavefront can be considered as a sources of secondary spherical wavelets. This concept normally belongs to physical optics. The twin ray is emitted from the exact same object point but traced in a slightly different direction, which can be assumed by invoking Huygens's principle, and defined in a special way that consistently prevents vignetting. This requires high-precision ray-tracing, which is introduced along with this thesis work as part of the appendix. The application of this concept is exemplified in finding the exit pupil of the Ritchey-Chrétien telescope. It can be modified to work in a plurality of cases and find the precise image location in three-dimensions, making it completely general and useful. Mastering the ray-tracing documented here depends on how much optics the user knows, but tracing a single ray is something that can be learned in minutes. I welcome you to freely use it and make it your own. If your goal is to learn to ray-trace in Mathematica, the reader is directed to the appendix, especially to the four-port polarimeter example, as it is a 3D system that contains both reflection and refraction through thin films, thick films, retarders, and a single surface is traced at a time!