Wind turbines connected to the distribution network can be the cause of voltage fluctuations and resulting fluctuations in the light intensity emitted by light bulbs. These fluctuations may cause people disturbance. A model has been developed to obtain a flicker prediction which is useful in the design process of a wind farm. The model is based exclusively in the frequency domain (FD). This new approach allows very fast and efficient evaluation. The impact of individual parameters is often easier to recognise and evaluate in a FD-representation. The following factors leading to flicker disturbances from a wind farm have been considered in detail: The wind spectrum: Effects of terrain and wind farm wakes on the wind turbulence spectrum have been considered and existing models have been expanded. The wind coherence: A new coherence model for large separation distances has been derived for use within a wind farm. Effects of the terrain on the coherence of power produced by turbines within a wind farm have been considered. The wind turbine: A simplified dynamic wind turbine model allows the prediction of turbine specific contributions to flicker for a variety of wind turbines using a minimal set of parameters. The flickermeter: Flicker measurements are found to sometimes neglect the impact of low frequency voltage variations. These are found to be very important for the correct flicker prediction. A new FD-flickermeter has been developed. The model has been validated against experimental data and a sensitivity analysis shows which parameters are most likely to influence the voltage flicker and which are best altered to minimise the flicker.

I propose and demonstrate a method by which barium titanate nanoparticle clusters can be used as exogenous contrast agents in Second Harmonic Optical Coherence Tomography imaging systems to localize and highlight desired regions of tissue. SH-OCT has previously been used to identify collagen within OCT images. However, SH-OCT signals from collagen are highly susceptible to inferior reflector artifacts because most of the second harmonic generated light is forward scattered. Second harmonic generating nanoparticle clusters exhibit high scattering properties, which can give them the advantage of backscattering a large quantity of second harmonic light while attenuating the forward scattered light. In this research project, a mathematical model is proposed in which the backward to forward scattering ratio of second harmonic generated light from nanoparticle layers is exponentially proportional to the thickness of the layer. This model was supported by measurements of the backward to forward scattering ratio of second harmonic light in barium titanate nanoparticles layers. This indicates that nanoparticle clusters can be designed and manufactured with the proper thickness so that they generate a large second harmonic signal without creating inferior reflector artifacts.

Spectral domain optical coherence tomography (SD-OCT) is a dispersed interferometric technology used to obtain tomographic images, typically of tissue for medical applications. OCT is a competing technology with confocal microscopy (CM) and confocal fluorescent microscopy (CFM), which are both used for biopsy imaging for pathology as the gold standard. OCT offers several advantages over CM/CFM: it is able to acquire a full 3D image in a single pass, it requires little or no sample preparation time, and the axial (depth) and lateral (transverse) resolution are not dependent on one another. SD-OCT is limited in imaging depth to a few millimetres due to the quality performance of the spectrograph section of the instrument--that which determines the sensitivity of the SD-OCT system. In this thesis a design for an SD-OCT system is presented that is suitable for biopsy imaging for pathological studies, i.e. an OCT microscope. The purpose of this system is to provide a fast diagnosis to be made in a surgical environment to reduce the amount of tissue removed from a patient and lower the chance of a returned visit at a later date due to insufficient tissue removal. The secondary purpose of the SD-OCT microscope is to serve as a research testbed system for implementing novel hardware advancements. One such technology, called an optical pupil slicer (OPS), will be implemented in the instrument to improve the depth imaging performance of the SD-OCT system over conventional SD-OCT systems. The OPS is a device that generally improves the performance of a dispersive-type spectrograph by increasing the spectral resolution without a loss in throughput, thereby increasing the sensitivity of the SD-OCT system.

Optical Coherence Tomography (OCT) is a relatively new interferometric technology that allows for high-resolution and non-destructive tomographic imaging. One of its primary current uses is for in vivo and ex vivo examination of medical samples. It is used for non-destructive examination of ocular disease, dermatological examination, blood vessel imaging, and many other applications. Some primary advantages of OCT imaging include rapid imaging of biological tissue with minimal sample preparation, 3D high-resolution imaging with depth penetrations of several millimeters, and the capability to obtain results in real time, allowing for fast and minimally invasive identification of many diseases. Current commercial OCT systems rely heavily on optical fiber-based designs. They depend on the robustness of the fiber to maintain system performance in variable environmental conditions but sacrifice the performance and flexibility of free-space optical designs. We discuss the design and implementation of a free-space OCT interferometer that can automatically maintain its alignment, allowing for the use of a free-space optical design outside of tightly controlled laboratory environments. In addition, we describe how similar enhancements can be made to other optical interferometric systems. By extending these techniques, we can provide similar improvements to many related fields, such as interferometric metrology and Fourier Transform Spectroscopy. Improvements in these technologies can help bring powerful interferometric tools to a wider audience.

Light delivery and sample handling systems are essential for any high performance imaging application. The custom design for two such devices with medical imaging applications are presented. The first device, a galvanometer-stage combination, is for general use optical coherence tomography and can be configured to scan over a large range of sample sizes and types. The second device, constructed in parallel, a rotation-linear stage combination, has been carefully designed for a specific imaging task: assessing tumour margins. The design of the two devices is driven by operational requirements and although requirements vary greatly from application to application, there are several common parameters that must be considered for every system. In this thesis, parameters like total scan time, scan resolution, sampling rate, and sample type flexibility are analysed and are some of the primary factors that influence the viability of a system for further development. This work's contribution to medical imaging research is the design of two light delivery systems and an analysis process that can be applied to future iterations of scan systems. The devices are shown to be flexible enough for use in test-bed systems, while providing the necessary functionality to meet the needs of medical histology and pathology. Controlling the light delivery and sample positioning of an imaging device adds important functionality to a scan system and is not a trivial task when high spatial-resolution scan spacing is required. The careful design of an imaging system to meet the unique requirements of the application enables better information and better resulting decision making. Advanced imagery provides new insights and perspectives to everyday scenes. It is these new perspectives that allow for re-evaluation and examination of problems with a fresh eye.

The main objective of this thesis is to investigate the intrinsic optical signals (IOSs) with an ultra-high resolution optical coherence tomography system (UHROCT). In order to study the retinal IOSs evoked by visible light, an UHROCT and an Electroretinogram (ERG) system was combined. An animal model (chicken retina) based on its retinal avascularity and cone dominance, was selected. Imaging the chicken retina with OCT resulted in high contrast, high resolution (~3μm axial and ~5 μm lateral resolution) 2D and 3D volumetric tomograms, in which all retina layers were clearly distinguishable. Using the combined UHROCT and ERG system to image IOSs from the chicken retina exposed to visible light (7ms green flash) resulted in highly reproducible IOS recordings from all retinal layers for the first time. All inner retinal layers showed an initial increase and subsequently a decrease in the intensity of the backreflected imaging light within the first 100 ms after the onset of the stimulus. Outer segments of the photoreceptors also showed a decrease in the backreflected imaging light within 100 ms after the onset of the flash. All retinal layers showed a strong decrease in the backreflected light within 150 to 175 ms after the onset of the flash. Imaging the pupil dynamics of the chicken with a modified combined UHROCT and ERG system showed that part of the strong negative IOSs observed in all retinal layers resulted from the vignetting of the imaging beam due to the light induced pupil constriction. Thorough analysis of the pupil dynamics acquired with UHROCT showed a time dependent effect of the anesthesia agent on pupil constriction. Further experiments to investigate an anesthesia effects on retinal function showed significant changes in ERG components. Statistical analysis showed that Isoflurane anesthesia severely affects the inner retinal response. In conclusion, it was hypothesized that the fast IOSs within ~50-100 ms after the onset of the visual stimulus originated from the neuronal tissue in the retina and are related to tissue optical property changes as a result of the electrical signal propagation in the light activated retina. Longer term decreases in backreflected light are likely due to pupil changes.

The 87Rb 49s->48s Rydberg state transition was rendered insensitive to electric field fluctuations about a 1V/cm dc electric field. This was accomplished by applying a non-resonant 38.445GHz microwave field to modify the electric dipole moment difference between the two states involved. This effect can be used to preserve the coherence of Rydberg state qubits in the presence of varying electric fields.

The changes in the human crystalline lens shape and its internal structure during accommodation and with aging are a fundamental component of the dynamic mechanism of accommodation and presbyopia, the loss of near vision with age. A better understanding of the crystalline lens changes during accommodation will help in developing new treatments to correct for presbyopia. The goal of this dissertation is to design and develop an imaging system to study the dynamic changes in lens shape during accommodative response. An imaging system based on spectral domain optical coherence tomography (SD-OCT) was developed with long axial range, high axial and lateral resolution and high speed for in vivo imaging the anterior segment along its entire length at video-rate. A slit-lamp mounted optical delivery scanning device for the extended depth SD-OCT system was developed. The delivery system was combined with a custom made unit that provides accommodation and disaccommodation step stimuli. A method to correct for the distortions of the OCT images was also developed that provides corrected two dimensional biometric data at different accommodative states.

An electrochemical sensor array can provide information about the spatial and temporal distribution of chemicals in liquid turbulent plumes. Planar laser induced fluorescence (PLIF) and amperometric sensor arrays were used to record signals from modulated chemical plumes released into a recirculating aquatic flume. Coherence analysis was applied to extract the frequency components contained in the sensor response. Effects due to release distance, modulation frequency, and array orientation were investigated. This study has demonstrated that frequency encoded information can be extracted from a turbulent chemical plume using an array of amperometric sensors with optimized three-dimensional geometry and tuning.

The main objective of this thesis is to investigate the intrinsic optical signals (IOSs) with an ultra-high resolution optical coherence tomography system (UHROCT). In order to study the retinal IOSs evoked by visible light, an UHROCT and an Electroretinogram (ERG) system was combined. An animal model (chicken retina) based on its retinal avascularity and cone dominance, was selected. Imaging the chicken retina with OCT resulted in high contrast, high resolution (~3μm axial and ~5 μm lateral resolution) 2D and 3D volumetric tomograms, in which all retina layers were clearly distinguishable. Using the combined UHROCT and ERG system to image IOSs from the chicken retina exposed to visible light (7ms green flash) resulted in highly reproducible IOS recordings from all retinal layers for the first time. All inner retinal layers showed an initial increase and subsequently a decrease in the intensity of the backreflected imaging light within the first 100 ms after the onset of the stimulus. Outer segments of the photoreceptors also showed a decrease in the backreflected imaging light within 100 ms after the onset of the flash. All retinal layers showed a strong decrease in the backreflected light within 150 to 175 ms after the onset of the flash. Imaging the pupil dynamics of the chicken with a modified combined UHROCT and ERG system showed that part of the strong negative IOSs observed in all retinal layers resulted from the vignetting of the imaging beam due to the light induced pupil constriction. Thorough analysis of the pupil dynamics acquired with UHROCT showed a time dependent effect of the anesthesia agent on pupil constriction. Further experiments to investigate an anesthesia effects on retinal function showed significant changes in ERG components. Statistical analysis showed that Isoflurane anesthesia severely affects the inner retinal response. In conclusion, it was hypothesized that the fast IOSs within ~50-100 ms after the onset of the visual stimulus originated from the neuronal tissue in the retina and are related to tissue optical property changes as a result of the electrical signal propagation in the light activated retina. Longer term decreases in backreflected light are likely due to pupil changes.