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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
21

Functionalization of Diamond and Its Application in High Performance Liquid Chromatography and Solid Phase Extraction

Saini, Gaurav 13 October 2010 (has links) (PDF)
The primary focus of my work was to chemically functionalize diamond as normal and reversed phases for solid phase extraction (SPE) and high performance liquid chromatography (HPLC). Diamond was functionalized with -NH2 groups via self-limiting adsorption of an amine-containing polymer, polyallylamine (PAAm), onto oxidized diamond particles. The chemical stability of these particles was improved by thermal curing or chemical crosslinking with 1,2,5,6-diepoxycyclooctane. The reversed phase material for SPE was synthesized by reacting amine-functionalized diamond particles with long chain alkyl and a perfluorinated isocyanate. Unlike commercially available silica, functionalized diamond particles were stable under extreme pH conditions (pH 0-14). Functionalized diamond particles were used for SPE, although their lack of porosity resulted in poor analyte capacity. To create materials with greater surface area, core-shell diamond particles were synthesized via layer-by-layer deposition of PAAm and nanodiamond onto solid microdiamond. These particles had higher surface areas than solid diamond particles, and their application in SPE and HPLC was demonstrated. As a related project, I demonstrated microlens array patterning (MAP) for selective adsorption of PAAm during microarray fabrication. Initially, alkyl monolayer terminated silicon surfaces were photopatterned with thousands of wells using a microlens array. PAAm was then deposited in the presence of a cationic surfactant to limit nonspecific adsorption of PAAm. Finally, reactions of selectively adsorbed PAAm were shown with glutaric anhydride, phenylenediisothiocyanate, biotin NHS-ester and an oligonucleotide (DNA). My third project concerned the synthesis of an abrasion resistant hydrophobic coating on the surface of nylon and silicon oxide substrates using chemical vapor deposition (CVD) of two silanes. The synthesis consists of four steps: 1) plasma oxidation of the substrate, 2) treatment with 3-isocyanatopropyltrimethoxysilane, 3) exposure of the treated surfaces to water vapors, and 4) treatment with a perfluorinated silane to make the surfaces hydrophobic. The coating is not visible to the eye and does not change the feel of the surface. Time-of-flight secondary ion mass spectrometry (ToF-SIMS), X-ray photoelectron spectroscopy (XPS), spectroscopic ellipsometry, contact angle goniometry, scanning electron microscopy (SEM), environmental scanning electron microscopy (ESEM), Rutherford backscattering spectroscopy (RBS) and nuclear reaction analysis (NRA) were used to characterize the resulting materials.
22

Tunable liquid crystal polarization gratings

Shi, Lei 01 December 2009 (has links)
No description available.
23

Achromatic Liquid Crystal Electro-Optical Devices Based On a Twisted Vertical Alignment Configuration

Chang, Kai-Han 18 April 2018 (has links)
No description available.
24

MICROMACHINED MAGNETIC DEVICES FOR ELECTRON BEAM CONTROL IN THE ELECTRON BEAM MICROCOLUMN

RONG, RONG 03 July 2007 (has links)
No description available.
25

Design and fabrication of embedded air void backlight module without substrate

Yang, Ho-Chi 31 August 2011 (has links)
The development and application of portable LCD (Liquid crystal display) technology is the main trend on the market. The goal of this study is to fabricate a compound optical film, and we focus on the design and fabrication of a new type backlight module for side-LED (Light emitting diode) display. The optical efficiency can be improved via the compound optical film. The profile of optical film was determined using commercial optical software, FRED. The mold with multi aspect ratio and multi fill-factor microlens array by LIGA-like process (Lithographie galvanoformung abformung) was produced using THB-126N negative photoresist and AZ-4620 positive photoresist. The study presents many innovative processes, such as the homemade gray scale mask, and multi-step electroforming method, which both produces the microlens array with variable size and aspect ratio. In addition, the embedded micro-void caused light guide and diffusion under the quantitative control during the PDMS (Polydimethylsiloxane) optical film fabrication. The compound optical film with embedded micro-voids, multi aspect ratio and variable size microlens array can be fabricated quickly without substrate. Then the optical properties were analyzed by BM-7A to characterize the luminance, uniformity and optical efficiency.
26

Investigation of the Optical Effects of Single Point Diamond Machined Surfaces and the Applications of Micro Machining

Li, Lei 30 September 2009 (has links)
No description available.
27

Generation of 3D autostereoscopic integral images using computer simulated imaging systems

Salih, Shafik January 2015 (has links)
Production of artificial Three-Dimension (3-D) images was the aim of many researches over hundreds of years. 3-D images are the images that create sense of depth when viewing them. 3-D images are closer to the real world scenes than 2-D images due to the 3-D effect or the sense of depth the 3-D images provide. Sense of depth can be caused by binocular cues including convergence and parallax. Convergence is created by the difference between the angles of the left eye and the right eye viewing axes. Parallax is the effect of viewing with one eye a view of the scene that is inherently shifted to the view seen by the other eye. Several techniques have targeted the creation of 3-D images with the mentioned cues. The technique is preferred when it is able to create 3-D images so that the viewer can view these images without wearing special glasses and the occurrence of viewer fatigue. Integral photography that was invented in 1908 is able to meet the previous requirements. Based on integral photography, several techniques, research and studies have been published. The purposes of this thesis include the computer simulation of flexible integral photography systems, the computer generation of good quality 3-D static and animated integral images using the simulated systems, optimising the generation process to be more accurate, less expensive, more effective, and faster, and producing a portable specialist software tool to achieve these targets. New techniques and algorithms are needed to meet these purposes. A literature survey was carried out about the closest researches and studies to the subject of computer-generated integral images; these were compared with the new techniques introduced in this study to prove the advantages and the necessity of these new techniques. The closest technique to the suggested techniques was implemented using more developed tools to compare the quality of the resulting integral images with the targeted integral images that are going to be produced using the tools and algorithms proposed in this thesis. A method to simulate an imaging system and produce integral images based on the new technique of dividing the view volume of the scene was introduced, explained, proved, and implemented with a program designed for this purpose. To optimise the processing time and the image quality, the previous method is developed, new features are added to the resulting integral images, and better performance was achieved by introducing the method of Displacing the Virtual Camera Target (DCT). Application software with Graphical User Interface is designed and implemented to allow users to select the required parameters of the imaging system and the required features of the resultant integral images. The software tool that is based on the developed techniques and employing OpenGL is useful to simulate the imaging systems, tune their parameters before the actual implementation of these systems, and as a result, save time and materials when designing these systems. The introduced techniques and the software tools are faster, more effective, and cheaper original methods to help in optimising both the integral imaging systems and the quality of integral images. These software tools based on the new techniques can be used on a wide range of devices and platforms because these are employing the portable Application Interface OpenGL. With these methods, integral imaging systems are simulated, and optimised; good quality static and animated integral images were created.
28

Self-Assembly of Poly(N-isopropylacrylamide) Microgel Thin Films

Serpe, Michael Joseph 04 October 2004 (has links)
The assembly of poly(N-isopropylacrylamide-co-acrylic acid) (pNIPAm-co-AAc) microgel thin films into disordered and ordered arrays was investigated. Disordered pNIPAm-co-AAc microgel arrays were assembled based on electrostatic attractions between polyanionic pNIPAm-co-AAc microgels and polycationic poly(allylamine hydrochloride) (PAH). These interactions were studied in solution and subsequently used to assemble thin films following a Layer-by-Layer assembly protocol. Thin films were assembled as a function of pNIPAm-co-AAc microgel solution temperature and the resultant film thermoresponsivity characterized as a function of microgel layer number and pH. The response of assembled thin films to pH 3.0 and 6.5 exposure was then characterized by quartz crystal impedance and surface plasmon resonance spectroscopy, which showed that the thin film solvation was highly dependent on the pH of the solution it was in. Assembled thin films were also shown to be useful as controlled drug delivery platforms, where it was found that small molecules could be released from the films in a temperature regulated fashion. Microgel thin films also exhibited unique optical properties and were used as microlens arrays, which were able to focus pattern in air as well as in solution and had focal lengths that could be tuned in response to pH and temperature changes. Ordered microgel arrays were assembled following a thermal annealing process, in order to make light diffracting materials. These ordered arrays were photopolymerized and exhibited temperature dependent Bragg diffraction properties.
29

Photopolymère pour le proche infrarouge : application à la fabrication de microlentilles sur composants optiques par écriture directe / Photopolymer for near-infrared polymerisation : Application to the fabrication of microlenses on optical components by direct writing

Dika, Ihab 21 September 2015 (has links)
L’objectif de cette thèse est de développer un nouveau matériau photopolymère pouvant être microstructuré dans la gamme de longueur d'onde du proche infrarouge (NIR). Le but final de ce travail est de proposer des solutions innovantes pour l'intégration de micro-optique sur les VCSELs (Vertical-Cavity Surface-Emitting Laser), sources lumineuses miniaturisées utilisées dans de nombreuses applications en optique, photonique, capteurs ou biologie. Le verrou technologique principal a consisté à développer et étudier le photopolymère adéquat pour la microfabrication déclenchée par le VCSEL. La difficulté principale tient à la longueur d'onde de photopolymérisation qui est fixé par le VCSEL et qui a obligé à développer un système moléculaire nouveau pour une polymérisation radicalaire à 780 et 850 nm. Une part importante du travail a consisté à étudier les mécanismes photophysiques et photochimiques des matériaux permettant de proposer des systèmes efficaces, sur le plan de la photophysique, de la photochimie de photopolymérisation et également une approche originale a été développée pour appréhender de façon quantitative les phénomènes de diffusion du colorant dans la matrice polymère. Sur la base des systèmes moléculaires proposés, la démonstration de l'intégration de microlentilles sur VCSEL par ce procédé innovant a pu être démontré. Les VCSELs lentillés ont été caractérisés et des propriétés très intéressantes pour la focalisation ont été démontrées. / The objective of this thesis is to develop a new photopolymer material that can be microstructured in the wavelength range of near-infrared (NIR). The ultimate aim of this work is to propose innovative solutions for micro-optical integration on VCSELs (Vertical-Cavity Surface-Emitting Laser). These miniaturized light sources are used in many applications in optics, photonics, sensors or biology. The main technological challenge was to develop and explore a new photopolymer compatible with a microfabrication initiated by the VCSEL. The main difficulty was to develop a new molecular system for radical polymerization at 780 and 850 nm, which is the wavelength emitted by the VCSEL. An important part of the work consisted to study the photophysical and photochemical mechanisms of this photopolymer in order to provide efficient systems in terms of photophysics, photochemistry of the photopolymerization. An original approach was developed to quantitatively apprehend the phenomena dye diffusion in the polymer matrix. Based on the proposed molecular systems, demonstrating the integration of microlenses on VCSELs by this innovative process could be shown. The lensed VCSELs have been characterized and very interesting properties for focusing have been demonstrated.
30

Fabrication of Precise Optical Components Using Electroforming Process and Precision Molding

Zolfaghari Abbasghaleh, Abolfazl 19 November 2021 (has links)
No description available.

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