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Metasurfaces are arrays of subwavelength meta-atoms that shape waves in a compact and planar form factor. During recent years, metasurfaces have gained a lot of attention due to their compact form factor, easy integration with other devices, multi functionality and straightforward fabrication using conventional CMOS techniques. To provide and evaluate an efficient metasurface, an optimized design, high resolution fabrication and accurate measurement is required. Analysis and design of metasurfaces require accurate methods for modeling their interactions with waves. Conventional modeling techniques assume that metasurfaces are locally periodic structures excited by plane waves, restricting their applicability to gradually varying metasurfaces that are illuminated with plane waves. In this work, we will first provide a novel technique that enables the development of accurate and general models for 1D metasurfaces. This approach can be easily extended to 2D metasurfaces. Due to the remarkable importance of accurate characterization of metasurfaces, we will provide a rigorous method to characterize 1D metasurfaces. Finally, we will provide an accurate approach to fabricate and characterize 2D metasrufaces.

Orthodox optical devices, such as lenses, mirrors, and prisms, are composed of solidstate materials, which although well studied and implemented ubiquitously are severely limited in their adaptable properties. An arguably new field of adaptive optics has emerged to further expand photonic manipulation competences of optical components. Fluid-based adaptive optical components were introduced as early as 1968 [1]; such components have the ability to change the shape of their interface surface, thus allowing for a variable curvature profile. The method of manipulation varies greatly, as does the range of surface deformations. A solid-state optical component is affected by system vibration variation only (difference in vibration from one component to the other due to damping effect). By comparison, two large limiting factors of a fluid-based adaptive optical component are the effect of local vibrations on the surface of the device and gravitational effect (when the optical axis of a lens is positioned parallel to gravitational pull). Such a gravitational effect has been mitigated by the invention of the mechanical electrowetting lens [2], which uses density matching of two liquids that make up an adaptive lens. However, this configuration creates an extra limiting factor of density matching two optically clear fluids with a desirable transmission spectrum. This method can also become bulky when a large aperture is needed. In this thesis, two adaptive lens systems are explored. Principles of operation, performance, limitations, as well as future improvements are studied and theorized. iv The first lens uses an optically clear elastomer as the substrate of an adaptive lens and a primitive mechanical manipulation to turn a plano–plano lens into a plano–convex lens. The second lens is composed of an optically clear gel rather than a fluid. Both methods exhibit excellent optical properties regardless of the orientation about the gravitational pull and significantly limit local vibration affects simply by the physical nature of the chosen materials.

Laser drilling of microvias for organic packaging applications is studied in present research. Thermal model is essential to understand the laser-materials interactions and to control laser drilling of blind micro holes through polymeric dielectrics in multilayer electronic substrates. In order to understand the profile of the drilling front irradiated with different laser beam profiles, a transient heat conduction model including vaporization parameters is constructed. The absorption length in the dielectric is also considered in this model. Therefore, the volumetric heating source criteria are applied in the model and the equations are solved analytically. The microvia drilling speed, temperature distribution in the dielectric and the thickness of the residue along the microvia walls and at the bottom of the microvia are studied for different laser irradiation conditions. An overheated metastable state of material is found to exist inside the workpiece. The overheating parameters are calculated for various laser drilling parameters and are used to predict the onset of thermal damage and to minimize the residue. As soon as a small cavity is formed during the drilling process, the concave curvature of the drilling front acts as a concave lens that diverges the incident laser beam. This self-defocusing effect can greatly reduce the drilling speed. This effect makes the refractive index of the substrate at different wavelengths an important parameter for laser drilling. A numerical thermal model is built to study the effect of self-defocusing for laser microvias drilling in multilayer electronic substrates with Nd:YAG and CO2 lasers.. The laser ablation thresholds was calculated with this model for the CO2 and Nd:YAG lasers respectively. Due to the expulsion of materials because of high internal pressures in the case of Nd:YAG laser microvia drilling, the ablation threshold may be far below the calculated value. A particular laser beam shape, such as pitch fork, was found to drill better holes than the Gaussian beam in terms of residue and tapering angle. Laser beam shaping technique is used to produce the desired pitchfork beam. Laser beam shaping allows redistribution of laser power and phase across the cross-section of the beam for drilling perfectly cylindrical holes. An optical system, which is comprised of three lenses, is designed to transform a Gaussian beam into a pitchfork beam. The first two lenses are the phase elements through which a Gaussian laser beam is transformed into a super Gaussian beam. The ray tracing technique of geometrical optics is used to design these phase elements. The third lens is the transform element which produces a pitchfork profile at the focal plane due to the diffraction effect. A pinhole scanning power meter is used to measure the laser beam profile at the focal plane to verify the existence of the pitchfork beam. To account for diffraction effect, the above mentioned laser beam shaping system was optimized by iterative method using Adaptive Additive algorithm. Fresnel diffraction is used in the iterative calculation. The optimization was target to reduce the energy contained in the first order diffraction ring and to increase the depth of focus for the system. Two diffractive optical elements were designed. The result of the optimization was found dependent on the relation between the diameter of the designed beam shape and the airy disk diameter. If the diameter of the designed beam is larger, the optimization can generate better result. Drilling experiment is performed with a Q-switched CO2 laser at wavelength of 9.3 μm. Comparison among the drilling results from Gaussian beam, Bessel beam and Pitchfork beam shows that the pitchfork beam can produce microvias with less tapering angle and less residue at the bottom of the via. Laser parameters were evaluated experimentally to study their influences on the via quality. Laser drilling process was optimized based on the evaluation to give high quality of the via and high throughput rate. Nd:YAG laser at wavelengths of 1.06 μm and 532 nm were also used in this research to do microvias drilling. Experimental result is compared with the model. Experimental results show the formation of convex surfaces during laser irradiation. These surfaces eventually rupture and the material is removed explosively due to high internal pressures. Due to the short wavelength, high power, high efficiency and high repetition rate, these lasers exhibit large potentials for microvias drilling.

Gender lens investing (GLI) considers gender-based factors across the investment process to advance gender equality and better inform investment decisions. It recognizes that gender-based discrimination persists in many areas of society, including access to economic opportunities. The aim of this study is to understand GLI as a phenomenon using the feminist standpoint theory. The research question guiding this study is: how does the management team of a venture capital fund interpret and implement gender-lens investing? The study conducted an in-depth case study on Company X, a venture capital fund that invests with a gender lens. The results were supported by interviews with the management team and company documents and were categorised according to the interpretations of GLI and key lessons to fulfil the aim. We conclude considerable efforts are underway to achieve the end goal of gender equality, however, in view of the shortcomings discussed, there is still room for improvement. The results and discussion can be used to better understand the phenomenon of GLI and lessons in the development of gender-responsive investment strategies.

<p>Improved materials for implantation as intraocular lens (IOL) devices are needed to minimize the occurrence of posterior capsule opacification (PCO). In this work, novel polydimethylsiloxane (PDMS) loaded with matrix metalloprotease inhibitors (MMPI) were developed as model IOL materials.</p> <p>PDMS was chosen as silicones are currently used successfully as IOLs. Inhibitor release rates and amount of initial burst of drug-loaded PDMS could be controlled by changing solvent when loading into elastomer base, as well as drug loading method, and release buffer.</p> <p>Two lens epithelial cell lines were characterized for in vitro tests: FHL124 and HLE B3. These cell lines produce different combinations of extracellular matrix proteins when grown on various biomaterial surfaces. Significant differences between the two cell lines were observed both in collagen VIII and α-smooth muscle actin levels, both when cells were unstimulated, and as a result of epithelial to mesenchymal transition induced by treatment with transforming growth factor β2. FHL124 cells were selected in further tests due to their consistent expression of extracellular matrix components when exposed to different materials.</p> <p>Solutions of synthetic MMPI GM6001 and MMP 2/9 Inhibitor II, known to mitigate anterior subcataract formation, were released from PDMS and found to protect in a modest but significant way against protein profile changes and to delay migration. Due to the Zn²⁺ dependence of MMPs, chelators, including EDTA, TPEN and 1-10 phenanthroline were examined as alternative inhibitors. Only the latter was found to have a significant effect on cell migration rates in vitro. Sulfadiazine, due to its chemical resemblance to synthetic MMPI was determined to be the most efficient at reducing migration rates as well as to have the lowest toxicity.</p> <p>Overall, sulfadiazine was determined in this work to be a potentially effective solution to mitigating PCO. These results indicate that releasing MMPI molecules from PDMS as a model IOL is a promising way to mitigate aspects of PCO.</p> / Thesis / Doctor of Philosophy (PhD)

Computer Vision (CV) has become omnipresent in our everyday life and it’s starting to see more and more use in the industry. This movement creates a demand for ever more performant systems to keep up with the increasing demands in manufacturing speed and autonomous behaviours. Such computer vision (CV) systems need to run complex algorithms at real-time speed and sometime even in energy constrained systems. Thus efficient implementation of these algorithms are a must. One of those algorithm is the lens rectification algorithm (also sometime called undistortion algorithm) that is often one of the first algorithm to be used to correct for multiple imperfection that can occur in a camera and lens system. This algorithm has been implemented on FieldProgramable Gate Arrays (FPGAs) in past work but they either relied heavily on Dynamic Random Access Memory (DRAM) or used a subset of the full lens distortion model used by OpenCV and restricted themselves to small distortion amounts by having access to only parts of the image at a time. This thesis aims to create an open-source, DRAM-free FPGA implementation of the OpenCV lens rectification model of this algorithm, using the full 12-parameter model and allowing the use of any parameter which, to our knowledge, has not yet been implemented. To do so, a hybrid programming approach was taken meaning that both Hardware Descriptive Languages and High-Level Synthesis were used to arrive at the final implementation. The final implementation achieves 1300 frames per second with a sub-millisecond latency at a resolution of 320x240 on grayscale images. / Databearbetning (CV) har blivit allestädes närvarande i vårt vardagliga liv och det börjar se mer och mer användning inom industrin. Denna rörelse skapar ett efterfrågan på allt mer prestandastarka system för att hålla jämna steg med den ökande efterfrågan på tillverkningshastighet och autonoma beteenden. Sådana databearbetningssystem (CV) måste köra komplexa algoritmer i realtid och ibland även i energibegränsade system. Effektiva implementeringar av dessa algoritmer är därför ett måste. En av dessa algoritmer är linsrätningsalgoritmen (ibland även kallad oavvändningsalgoritm) som ofta är en av de första algoritmerna som används för att korrigera för flera fel som kan uppstå i ett kamerasystem och linssystem. Denna algoritm har implementerats på FieldProgramable Gate Arrays (FPGAs) i andra dokument tidigare, men de har antingen starkt beroende på Dynamic Random Access Memory (DRAM) eller använt en delmängd av den fullständiga linsdistortionmodellen som används av OpenCV och begränsat sig till små distortioner genom att ha tillgång till endast delar av bilden åt gången. Denna artikel syftar till att skapa en öppen källkod, DRAM-fri FPGA-implementering av OpenCV-linsrätningsmodellen av denna algoritm, med hjälp av den fullständiga 12-parametermodellen och tillåter användning av vilken parameter som helst, vilket inte har gjorts tidigare. För att göra detta togs ett hybridprogrammeringsansats, vilket innebär att både hårdvarubeskrivningsspråk och högnivåsyntes användes för att nå den slutliga implementeringen. Den slutliga implementeringen uppnår 1300 bilder per sekund med en sub-millisekund latens vid en upplösning på 320x240 på gråskalabilder.

With the increasing demand on wireless and portable devices, the radio frequency front end blocks are required to feature properties such as wideband, high frequency, multiple operating frequencies, low cost and compact size. However, the current radio frequency system blocks are designed by combining several individual frequency band blocks into one functional block, which increase the cost and size of devices. To address these issues, it is important to develop novel approaches to further advance the current design methodologies in both space and spectrum domains. In recent years, the concept of artificial materials has been proposed and studied intensively in RF/Microwave, Terahertz, and optical frequency range. It is a combination of conventional materials such as air, wood, metal and plastic. It can achieve the material properties that have not been found in nature. Therefore, the artificial material (i.e. meta-materials) provides design freedoms to control both the spectrum performance and geometrical structures of radio frequency front end blocks and other high frequency systems. In this dissertation, several artificial materials are proposed and designed by different methods, and their applications to different high frequency components and circuits are studied. First, quasi-conformal mapping (QCM) method is applied to design plasmonic wave-adapters and couplers working at the optical frequency range. Second, inverse QCM method is proposed to implement flattened Luneburg lens antennas and parabolic antennas in the microwave range. Third, a dual-band compact directional coupler is realized by applying artificial transmission lines. In addition, a fully symmetrical coupler with artificial lumped element structure is also implemented. Finally, a tunable on-chip inductor, compact CMOS transmission lines, and metamaterial-based interconnects are proposed using artificial metal structures. All the proposed designs are simulated in full-wave 3D electromagnetic solvers, and the measurement results agree well with the simulation results. These artificial material-based novel design methodologies pave the way toward next generation high frequency circuit, component, and system design.

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