Abstract Tunable-focal length LC lens with hole-patterned electrode have been fabricated in this study. Liquid crystals (LCs) are excellent electro-optic materials with electrical and optical anisotropies. Their optical properties can easily be varied by external electric field. Hence according the electro-optic properties, we made the tunable LC lens. In this study a novel conoscopy method has been applied to analyze the LC lens. First, we study the causes of the focusing and the optical properties of LC lens, and measure the focal length with varying voltage. Second, by analyzing the figure patterns formed with conoscopy method. We study the LC molecules reorientation caused by the inhomogeneous electric field distribution. In order to improve the spoiled effect due to the subsidiary domain in the LC lens, three different structures of LC lens have been fabricated and the focusing effect has been discussed.

Advancements in the area of additive manufacturing have led to the development of new methods with the purpose of optimizing component properties and expanding operating environments. In a comparative study, the influence of process parameters including beam and laser current, translation speed, and wire feed and deposition rate on 316L stainless steel deposits produced by both Laser Engineered Net Shaping (LENS®) and Electron Beam Freeform Fabrication (EBF3) processes are investigated. Tensile tests are used to obtain information on the mechanical properties of the specimens. A metallographic analysis is performed using optical microscopy and SEM to characterize solidification grain structure, porosity, secondary dendrite arm spacing, and possible modes of failure. This study highlights the distinct characteristics of both additive methods and how they lead to different microstructure and mechanical properties. Also included in this study is the upgrade and repair of the LENS machine at CAVS.

By using a special design of electrode pattern and the differential biased circuit, the gradient of the electric field distribution inside the liquid crystal sample cell can be achieved through the adjustment of driving voltage. The characteristics of positive or negative types of lens can be converted by changing the polarity of gradient within the sample cell which posses the homogeneous alignment. The liquid crystal lens with a variable focal length and the tunable types of focusing is demonstrated by utilizing the controllable distribution of electric field. This special design incorporating with the fabrication technology of TFT has a potential to develop a large scale of liquid crystal lens.

Fisheye lenses refer to ultra-wide angle lenses that have field of view equal or larger than 180 degrees. Such lenses introduce large amount of barrel distortion to capture at least the entire hemisphere in front of the lens. Fisheye lenses were initially designed for scientific use, such as cloud recording and angle measuring, and were widely used for commercial purposes later. The development of photographic fisheye lenses started in 1960s. However, the lack of detailed references on photographic fisheye lens design makes such design challenging. This thesis provides detailed introduction of photographic fisheye lens design for 35mm format DSLR cameras. A discussion on the history of fisheye lenses is provided to describe the development of fisheye lenses. The tangential and sagittal magnifications are mathematically derived for each fisheye lens projection mapping method to show their differences. The special properties and design issues of photographic fisheye lenses are described in detail. Along with each design issue, some solutions suggested by the author are also provided. The performance of the current diagonal fisheye lenses for 35mm DSLR cameras are evaluated in detail. Then a new diagonal fisheye lens designed by the author is presented and compared with the current diagonal fisheye lenses on the market. Finally, a zoom fisheye lens designed for 35mm DSLR cameras is presented and discussed.

Ultrastructural observations on the six-day chick embryo lens reveal that fibre cell differentiation, which involves extensive cell elongation, is characterized by the presence of numerous oriented microtubules and by marked changes in intercellular relationships which are felt to be important for cell extension. Increased Golgi activity in cells initiating elongation appears to be related to the formation of intercellular junctions and the elaboration of new surface membrane. Studies concerning the differentiation in vitro of anterior lens epithelia demonstrate that their cells elongate either to a great extent or to a limited extent, depending on factors deriving from the epithelial conformation.The conformation of an explanted anterior lens epithelium can be manipulated so that its cells elongate consistently to either a limited or a great extent. These cells, whether elongated to a limited or to a great extent, are ultrastructurally similar with respect to features reflecting cytoplasmic differentiation, including those important for morphogenesis. Their fine structure closely resembles that of fibre cells differentiating in vivo. The cells of anterior lens epithelia differentiating in vitro, whether elongating to a limited or to a great extent, are the same in terms of the nature and relative proportions of their soluble proteins as indicated by polyacrylamide gel electrophoresis. There is a change in the relative proportions of the soluble proteins accumulated by the anterior lens epithelia when they differentiate in vitro that is similar to that which occurs in cells undertaking fibre cell differentiation in vivo. It is concluded that those factors deriving from the conformation of the anterior lens epithelium that affect the degree of elongation of its cells differentiating in vitro are physical in nature. Since such physical factors are important with regard to restraining or encouraging the expression of morphogenetic potential in vitro, it is suggested that similar physical forces are important in lens morphogenesis in vivo. Observations concerning anterior lens epithelia elongating to a great extent in vitro demonstrate that their cells progressively elongate for only about three days. Well differentiated explants cultured for longer periods do not show greater elongation or further cytoplasmic differentiation. Their cells, at the ultrastructural level, resemble differentiating fibre cells in vivo rather than differentiated ones. It is concluded that the anterior lens epithelium has some capacity for differentiation independent of the ocular environment, but that the latter is essential for the expression of its full developmental potential. / Science, Faculty of / Zoology, Department of / Graduate

The eye forms through complex tissue interactions, and it still only partly understood. The developing vertebrate lens however, is crucial for coordinating eye development and eye growth, through releasing signals to surrounding eye structures. It is thought that the lens controls the growth of the eye through the production of the vitreous- the jelly-like substance that fills the main cavity of the eye and maintains the eye in its correct shape. Many components of the vitreous are produced by a region of the peripheral retina known as the ciliary body, and so it is believed that the lens controls eye growth through controlling the development of the ciliary body and thus, indirectly, the vitreous. This project addresses this concept. I have identified a previously unknown functional link between the lens and Vitamin A metabolism. The lens is important for maintaining retinoic acid production within the developing chick eye through controlling the expression of RDH10 in the presumptive ciliary body. RDH10 is important for the first step in retinoic acid synthesis, the conversion of Vitamin A into retinal, which is then converted into retinoic acid. The loss of RDH10 within the presumptive ciliary body is associated with a reduction in expression of other genes known to be involved in ciliary body development, BMP7, WNT2B and OTX1 along with a reduction in the growth of the eye. The reduction in retinoic acid production within the eye as a result of lens removal, in turn affects the synthesis of Collagen IX from the ciliary body, a major component of the vitreous. The data suggests that the lens controls retinoic acid production within the eye, through maintaining gene expression in the developing ciliary body. Retinoic acid signalling controls the synthesis of components of the vitreous, such as Collagen IX. The proper accumulation of the vitreous within the eye is crucial for the correct growth of the chick eye.

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