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1
Henderson, Philip Simon. "Durable optical coatings on glass." Thesis, University of Salford, 2002. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.395663.
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Jota, Thiago, and Thiago Jota. "Polarization Aberrations of Optical Coatings." Thesis, The University of Arizona, 2017. http://hdl.handle.net/10150/624138.
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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!
3
Inci, M. Naci. "Optical coatings for fibre optic sensors." Thesis, Heriot-Watt University, 1992. http://hdl.handle.net/10399/1455.
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Messerly, Michael Joseph. "Ion-beam analysis of optical coatings." Diss., The University of Arizona, 1987. http://hdl.handle.net/10150/184273.
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Rutherford backscattering spectrometry (RBS) is shown to be an elegant, powerful tool for the chemical characterization of optical coatings. RBS studies of several thin film materials are presented to illustrate the technique's unique abilities, and to show how RBS is best exploited in investigations of thin film stoichiometry and diffusion. The text begins with an introduction to optical coatings and the practical problems encountered in their implementation. The basic principles of RBS are discussed, and the technique is compared to other popular surface analysis tools. The introductory material concludes with a chapter devoted to specific techniques for RBS data and error analysis, including the derivation of a simple formula for determining the optimum thickness of multi-element samples. The accurate stoichiometric measurements provided by RBS give new insights into the chemical structure of ion-bombarded MgF₂ coatings. The analysis shows that lightly-bombarded coatings contain a small oxygen fraction (< 6%), and the absence of this oxygen in opaque, heavily-bombarded samples implies the oxygen compensates for fluorine deficiencies and is therefore an essential ingredient for transparent films. This beneficial oxygen appears to diffuse into the coatings along columnar voids, and the implied compromise between packing density and transparency is discussed. The final chapter takes advantage of the nondestructive depth-profiles provided by RBS. We present the first direct experimental verification of the interfacial oxide layer responsible for the superior adhesion of aluminum to glass, and show that contrary to popular belief, the layer is not an artifact of oxygen adsorbed during the aluminum's evaporation. We then discuss the diffusion of copper through silver films, and show that the migration is enhanced by exposure to the RBS probe beam. Finally, we consider the diffusion of carbon, from graphite substrates, into the voids of porous coatings during the RBS measurements. This effect, like the enhanced copper diffusion, is consistent with a low temperature, measurement-induced anneal; however, we show that the migrant carbon does not alter the chemical structure of the coatings, but instead serves as a convenient, non-intrusive indicator of film porosity.
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Giatti, Brandon. "Optical Properties of Nanostructured Dielectric Coatings." PDXScholar, 2014. https://pdxscholar.library.pdx.edu/open_access_etds/1940.
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Solar cells have extrinsic losses from a variety of sources which can be minimized by optimization of the design and fabrication processes. Reflection from the front surface is one such loss mechanism and has been managed in the past with the usage of planar antireflection coatings. While effective, these coatings are each limited to a single wavelength of light and do not account for varying incident angles of the incoming light source. Three-dimensional nanostructures have shown the ability to inhibit reflection for differing wavelengths and angles of incidence. Nanocones were modeled and show a broadband, multi-angled reflectance decrease due to an effective grading of the index.
Finite element models were created to simulate incident light on a zinc oxide nanocone textured silicon substrate. Zinc oxide is advantageous for its ease of production, benign nature, and refractive index matching to the air source region and silicon substrate. Reflectance plots were computed as functions of incident angle and wavelength of light and compared with planar and quintic refractive index profile models. The quintic profile model exhibits nearly optimum reflection minimization and is thus used as a benchmark. Physical quantities, including height, width, density, and orientation were varied in order to minimize the reflectance. A quasi-random nanocone unit cell was modeled to better mimic laboratory results. The model was comprised of 10 nanocones with differing structure and simulated a larger substrate by usage of periodic boundary conditions. The simulated reflectance shows approximately a 50 percent decrease when compared with a planar model. When a seed layer is added, simulating a layer of non-textured zinc oxide, on which the nanocones are grown, the reflectance shows a fourfold decrease when compared with planar models. At angles of incidence higher than 75 degrees, the nanocone model outperformed the quintic model.
6
Arnold, Matthew David, and n/a. "Growth and patterning of anisotropic optical coatings." University of Otago. Department of Physics, 2005. http://adt.otago.ac.nz./public/adt-NZDU20060811.155729.
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Physical vapour deposition at oblique angles produces coatings that have oriented internal structure, a consequence of self-shadowing and limited diffusion. Structured media have a number of useful properties, including form birefringence which affects the polarization of light. Whilst oblique deposition technology is mature, there is room for further exploration to open up new applications and provide further insight. One door only recently opened is lithographic patterning, and this thesis seeks to map out part of that frontier. Lithography allows rapid replication of a pattern, and is being extended to the nano-scale, via two routes identified as "top-down" and "bottom-up". In this thesis bottom-up processing is pursued as a secondary theme, developing computer programs for investigation of the effect of substrate patterning on growth and subsequent birefringence. The primary focus is the application of top-down patterning to obliquely-deposited polarizing elements, for the production of pixellated polarizing arrays.
The growth of obliquely deposited coatings is well understood, and the process has been developed using dynamic substrate rotation to produce several interesting morphologies. Standard results of computer simulations are replicated for illustration. The relationship between morphology and optical properties has been extensively studied from an empirical standpoint, resulting in production of polarizing elements such as retarders, linear- and circular- polarizers. Surprisingly little study has focussed on simulation of the optical anisotropy of arbitrary structures, and here programs are developed for initial prediction of the birefringence of coatings deposited over patterned substrates.
Top-down patterning approaches are directly applied to obliquely-deposited dielectric coatings. Standard reactive ion etching protocols are tested, particularly for silicon films, measuring the effect of deposition parameters on etch-rate. Lift-off patterning at significantly oblique angles requires special attention, and an undercut tri-layer process is developed, resulting in patterning of chiral oxide films. Additionally a novel masking process is developed, that allows the production of pixellated arrays comprised of different polarizers in a single coating operation. One such array is used as the essential component in the production of a space-multiplexed array polarimeter.
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Jarzebinska, Renata. "Tapered optical fibre sensors employing nanostructured coatings." Thesis, Cranfield University, 2010. http://dspace.lib.cranfield.ac.uk/handle/1826/5585.
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Tapered optical fibres have been manufactured, characterised and studied. These are
compact devices made from single-mode optical fibre. A system for producing tapers has
been developed, employing flame heating of the optical fibre and computer controlled
rotation stages to stretch the fibre in a controlled and repeatable fashion.
Subsequently tapered fibres were coated with nanostructured films of materials that change
their optical properties in response to an external stimulus. An investigation of the effect of
depositing chemically sensitive nano-scale films onto tapered optical fibres has been
undertaken. Three different methods of deposition were applied: Langmuir-Blodgett
technique, electrostatic-self-assembly and – for the first time - chemical grafting. Six
different films of materials were deposited onto tapered fibres: 4-[2-(4-dimethylamino-
naphtalen-1-yl)-vinyl]-1-octadecyl-quinolinium iodide (merocyanine dye),
calix[4]resorcinarene, bilayers of poly(allyamine hydrochloride) (PAH) and anionic
tetrakis(4-sulfophenyl)porphine (TSPP), PAH and cyclodextrine, TiO2 nanoparticles
imprinted with ((1-(4-Nitrophenylazo)-2-naphthol (NPAN) compound), polyaniline
(PANI). During the deposition process the light was launched into each fibre and the
evolution of the transmission spectrum observed.
The coated tapers were subsequently investigated for their potential application as
chemical sensors: pH, red-ox, ammonia sensors. The response to a stimulus was
investigated by immersing the coated tapered fibre in an environment containing the
measurand.
The properties of these devices were also used in combination other photonics concepts,
such as fibre Bragg gratings written in the tapered region of a fiber, under investigation
within the Engineering Photonics Group to develop new sensor elements.
8
Meister, Stefan. "Functional optical coatings on fiber end faces." Berlin mbv, Mensch-und-Buch-Verl, 2008. http://d-nb.info/995879184/04.
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Boudreau, Marcel Gerard. "Optical coatings for improved semiconductor diode laser performance." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1997. http://www.collectionscanada.ca/obj/s4/f2/dsk2/ftp02/NQ30075.pdf.
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Boudreau, Marcel G. "Optical coatings for improved semiconductor diode laser performance /." *McMaster only, 1997.
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Nabeerasool, Mohammed Akmez. "Evaluation of palladium optical coatings for hydrogen sensing." Thesis, University of Manchester, 2012. https://www.research.manchester.ac.uk/portal/en/theses/evaluation-of-palladium-optical-coatings-for-hydrogen-sensing(aa9e8126-133b-48f4-b0da-82f10d02b6ee).html.
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This thesis describes the development and characterisation of palladium optical coatings for hydrogen sensing. The main aim of the thesis was to optimise an optically interrogated palladium coated substrate to detect hydrogen at concentrations less than 1% in humid conditions (50-80%). An optical set up was constructed to investigate the change in the coatings in transmission at 650 nm on exposure to varying hydrogen concentrations in dry and wet conditions. Three different optical substrates; Polymer Optical Fibre (POF), Polymethyl methacrylate (PMMA) and glass were evaluated to determine the best support for palladium; criteria of selection were based on hydrogen detection performance in dry and humid condition (50%). PMMA was shown to be the ideal support as effect of humidity on hydrogen detection was minimal. Palladium was deposited by sputter coating technique and the coating thickness demonstrates a dependence on the deposition time and position of the substrate inside the coating chamber. The coating developed showed a response time of 1s at 5%H2, a detection range of 0-9.1% with a demonstrated detection limit of 200 parts per million (ppm) and a predicted limit of detection of 15 ppm. The rate of hydrogen detection was proposed to be diffusion limited for coating thickness up to the threshold thickness. At thicknesses less than the threshold thickness, the rate limiting step was related to the binding force between the coating and the support. The coating performance was unaffected by cross sensitive gases such as hydrogen sulphide, carbon monoxide, methane and ethene. In the presence of Relative Humidity (50-80%), the coating reached a limit of detection at 0.1% H2. However, over exposure to humidity lead to temperature effect which was compensated using a temperature compensation model developed. The surface of the coating developed was characterised by Atomic Force Microscopy (AFM), X-Ray Diffraction (XRD) and X-Ray Photoelectron Spectroscopy (XPS) and revealed that the coating developed is unaffected by the tests carried out through the PhD.
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Womack, Gerald. "Anti-reflection coatings and optical interference in photovoltaics." Thesis, Loughborough University, 2017. https://dspace.lboro.ac.uk/2134/25529.
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Light reflection from the glass surface of a photovoltaic (PV) module is a significant source of energy loss for all types of PV devices. The reflection at the glass and air interface accounts for ~4% of the total energy. Single layer anti-reflection coatings with sufficiently low refractive index have been used, such as those using magnesium fluoride or porous silica, but these are only effective over a narrow range of wavelengths. Multilayer-antireflection coatings reduce the weighted average reflection over the wavelength range used by solar technologies more effectively by utilising interference effects. Multilayer stacks consisting of silica and zirconia layers deposited using reactive magnetron sputtering and single layer porous silica coatings were compared in terms of effectiveness and durability. Details of the stack design, sputter deposition process parameters, and the optical and micro-structural properties of the layers of the multilayer coating are provided and similar properties where applicable for the single layer coatings. Anti-reflection coatings on glass exposed to the outdoors must not degrade over the lifetime of the module. A comprehensive set of accelerated environmental durability tests has been carried out in accordance with IEC 61646 PV qualification tests. The durability tests confirmed no damage to the coatings or performance drop as a result of thermal cycling or damp heat. All attempts to perform pull tests on either coating resulted in either adhesive or substrate failure, with no damage to the coating itself. Scratch resistance, abrasion resistance, and adhesion tests have also been conducted. The optical performance of the coatings was monitored during these tests and the coatings were visually inspected for any sign of mechanical failure. These tests provide confidence that broadband anti-reflection coatings are highly durable and will maintain their performance over the lifetime of the solar module. Additionally heat treatment experiments demonstrated both coatings can withstand up to 600°C temperatures and can thereby withstand CdTe manufacturing processes allowing for pre-coated glass. Additionally experiments demonstrated that multi-layer coatings are resistant to acid attack. Thin film photovoltaic devices are multilayer opto-electrical structures in which light interference occurs. Light reflection at the interfaces and absorption within the window layers reduces transmission and, ultimately, the conversion efficiency of photovoltaic devices. Optical reflection losses can be reduced by adjusting the layer thicknesses to achieve destructive interference within the structure of the cell. The light transmission to the CdTe absorber of a CdS/CdTe cell on a fluorine doped tin oxide transparent conductor has been modelled using the transfer matrix method. The interference effect in the CdS layer and high resistance transparent buffer layers (SnO2 and ZnO) has been investigated. The modelling shows that due to relatively high absorption within the SnO2 layer, there are modest benefits to engineering anti-reflection interference in the stack. However, a ZnO buffer layer has limited absorption and interference can be exploited to provide useful anti-reflection effects. Additionally the light transmission to the perovskite absorber of a thin film solar cell using fluorine doped tin oxide (FTO) transparent conductor has been modelled. Alternative transparent conductor materials have also been investigated including aluminium doped zinc oxide (AZO) and indium tin oxide (ITO) and shown to be beneficial to transmission.
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Topliss, Stephen M. "Optical fibre long period grating sensors with nanostructured coatings." Thesis, Cranfield University, 2011. http://dspace.lib.cranfield.ac.uk/handle/1826/6799.
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The dual resonant response of long period fibre gratings (LPG) operating near the phase matching turning point to the deposition of nanostructured coatings is explored. A broad range of LPGs have been fabricated with grating periods ranging from 80m to 180m, and these have been characterized with three different coating materials,-tricosensoic acid, undecyl-calix[4]resorcarene and tert-butyl-calix[8]arene carboxylic acid. The dual resonant response has been exploited with the construction of an LPG based sensor coated with a quinolinium dye forming a pH sensor. The wavelength response of this device was measured with a sensitivity of -0.55pH/nm.
Furthermore, length apodised phase shifted long period gratings have been characterized, and the effect on the dual resonant response has been recorded. Partial coating of this device has resulted in the observation of a bandgap feature in the wavelength response.
The use of calixarenes as a functional coating for long period fibre gratings is also investigated. Calixarene is applied in a thin layer with a thickness of several hundred nm’s to the cladding of the fibre in the region containing the LPG sensor. The chemical sensing capabilities of a long period fibre grating sensor is presented for the detection of the volatile organic compounds; hexane, cyclohexane, benzene and toluene. The wavelength response was measured and the sensitivity to toluene vapour was recorded at 1600ppmv/nm. Using intensity detection of the central maxima in the wavelength response, the chemical selectivity is demonstrated showing sensitivity to toluene vapour over 13 times greater compared to hexane vapour.
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Onifade, Ayokola. "Enhanced deposition of titanium (IV) oxide for optical coatings." Thesis, University of Salford, 2006. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.492432.
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TiO2 films are widely used as high refractive index dielectric layers in multi-layer optical devices and functional films. Indeed, the refractive index of titania is amongst the highest of the commonly used optical coating materials. Typical applications include low emissivity and solar control films, anti-reflection coatings and narrow bandpass filters. There are, though, two critical issues which affect the use of titania films in commercial products. First, it has a low deposition rate in comparison with other hi high index materials, such as Nb205. And, secondly, the optical properties of titania films, and their stability, are critically dependent on the film structure, which in turn, is dependent on the deposition conditions used.
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SAXE, STEVEN GARY. "ION-INDUCED PROCESSES IN OPTICAL COATINGS (BOMBARDMENT, THIN FILMS)." Diss., The University of Arizona, 1985. http://hdl.handle.net/10150/188076.
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Nearly all the deficiencies of conventional vacuum evaporated coatings trace to a single physical property of condensed films: low packing density. One way to increase packing density is to bombard the growing film with ions during deposition, called ion-assisted deposition (IAD). The beginning chapters of this dissertation analyze IAD as a perturbation of the conventional vacuum evaporation process. The experimental chapters begin with an examination of the effect on moisture penetration behavior of oxygen-ion bombarding completed optical filters. Moisture adsorption and desorption is retarded after bombardment in filters composed of titania and silica, but not in those of zirconia and silica. Bombardment evidently induces a crystalline-to-amorphous transition in titania, causing the surface to swell and occluding the pores. The transition in zirconia is the reverse, and no impediment to moisture appears. Argon-ion-assisted magnesium fluoride (MgF₂) can show ultraviolet (UV) absorption. The primary mechanism is probably the formation of F-centers (single fluorine-ion vacancies), although an unsaturated oxygen bond may also be responsible. Absorption can be removed by baking and often by irradiation with UV. After baking, fluorine is lost and replaced by oxygen. Absorption-free MgF₂ films can be deposited by minimizing the substrate temperature and bombardment flux. Ion-assisted films contain up to 2% argon and up to 170 parts-per-million of tungsten from the ion gun filaments. They show a slightly higher refractive index, are much less porous, and are much more resistant to damage by abrasion and exposure to fluorine gas. Ion-assisted aluminum oxide (alumina, Al₂O₃) films show a small increase in UV absorption after argon-ion bombardment; however, a mixture of argon and oxygen ions avoids the problem. Excess oxygen is often incorporated into alumina films, and depresses both the mass density and the refractive index. IAD increases refractive index and decreases porosity. Ion-assisted alumina films are somewhat more stable in humid environments. Ion-assisted deposition has been shown by this study to cause substantial improvements in many of the physical and some of the optical and chemical properties of evaporated magnesium fluoride and aluminum oxide films.
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Poland, Stephan H. "Applications of optical fiber sensors with thick metal coatings." Thesis, This resource online, 1994. http://scholar.lib.vt.edu/theses/available/etd-06232009-063456/.
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Bailleul, Carine Alice. "High-speed film forming." Thesis, Georgia Institute of Technology, 1995. http://hdl.handle.net/1853/19129.
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Abu-Hassan, L. H. "Optical studies of ion-beam irradiated LiF and SiO2̲." Thesis, University of Sussex, 1987. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.377056.
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Whitehead, David James. "Pulsed laser interactions with protective polymer coatings of optical fibres." Thesis, University of Hull, 2005. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.431050.
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Geng, Xuan. "Failure mechanisms of weak adhesion optical coatings under sliding contac." Paris 6, 2008. http://www.theses.fr/2008PA066447.
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Dans cette thèse, les mécanismes d’endommagement du verre revêtu sous contact glissant ont été étudiés à l’aide d’essais microscratch in situ. Dans un premier temps, la fissuration du verre revêtu d’une monocouche de Si3N4 a été comparée à la résistance à la rayure du verre nu. Les résultats sont discutés en termes de friction et de différence de module entre le revêtement et le substrat. Ensuite, un système bicouches Si3N4/Ag a été étudié. L'impact de l'épaisseur du revêtement sur l’amorçage d’une rayure a été étudié expérimentalement et numériquement. Enfin, un empilement multicouches modèle, constitué de couches de nitrure/oxyde et d'argent d'environ 100nm d'épaisseur, a été étudié. Les résultats montrent que l’amorçage de la rayure et la propagation stationnaire résultent de deux mécanismes très différents. Les propriétés interfaciales (coefficient de frottement et énergie d’adhésion) ont été mesurées et leur impact sur le mécanisme d’amorçage d’une rayure a été évalué par des analyses en éléments finis.
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George, Christopher David. "Nonlinear optical and electrical properties of hemicyanine dyes." Thesis, Cranfield University, 1997. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.284915.
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Harvey, Michael D. "Hybrid material systems for micro-optical devices : the synthesis and characterisation of dye doped mesostructured TiO2, low refractive index mesoporous SiO2 and the analysis of thin films made thereof /." [St. Lucia, Qld.], 2005. http://www.library.uq.edu.au/pdfserve.php?image=thesisabs/absthe19323.pdf.
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Day, Travis E. "Silicon Dioxide Planarization| Impacts on Optical Coatings for High Energy Laser." Thesis, Colorado State University, 2018. http://pqdtopen.proquest.com/#viewpdf?dispub=10690434.
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The work of this thesis is devoted to examining the impact of silicon dioxide (silica or SiO2) planarization on the optical properties and laser damage resistance of thin-film coatings. SiO2 planarization is a process to smooth out fluence limiting nodular defects within multilayer coatings for high-energy laser applications. Mitigating these defects will improve the power handling abilities and improve the lifetime of laser coatings.
Presented here is a combination of work with the aim of evaluating the optical and laser damage properties of SiO2 planarization within single layers, bilayers, and multilayers. As compared to control (non-planarized) samples, a 2–3x increase in the thin-film absorption, which decreases with post-process annealing, was discovered for SiO2 planarized samples. This suggests that planarization creates oxygen-related defects which can be annealed out and little impurity implantation. Investigations of laser damage resistance were carried out at λ = 1030nm and pulse durations of τ = 220ps and 9ps. The laser damage of single and bilayer coatings is known to be dependent on the substrate-coating interface and this is further evidenced within this thesis. This is because the effects of planarization are masked by the extrinsic laser damage processes within the single and bilayers. Slight change (< 15%) in the laser induced damage threshold (LIDT) at 220ps and 9ps was observed for planarized single and bilayers. Depending on coating design, post-process annealing was shown to increase the LIDT by ~10% to ~75% at 220ps and ~10% to ~45% at 9ps. Although the fused silica substrate surface LIDT was shown to follow the √τ pulse scaling law for pulses above ~10ps, the single and bilayer coatings do not follow this pulse scaling. The divergence from the √τ pulse scaling on the coatings suggests a variation in the laser damage initiation mechanisms between 220ps and 9ps.
Multilayer high-reflecting (HR) mirrors with varying planarization design were also damage tested. A 6–7 J/cm2 LIDT, with 220ps, was observed for HR coatings with SiO2 planarization layers within high electric-field areas within the coating. However, SiO2 planarization at the substrate-coating interface, where the electric-field is minimal, and control (non-planarized) was shown to have a LIDT of 63 ± 1.2 J/cm 2 and 21.5 ± 0.5 J/cm2 for 220ps, respectively. At 9ps, the LIDT varied less than 90% difference between the various planarization designs. The substrate-coating planarization multilayer and control coating had an equal LIDT of 9.6 ± .3 J/cm2 at 9ps.
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Melninkaitis, Andrius. "Optical resistance of dielectric coatings to multi-pulse femtosecond laser radiation." Doctoral thesis, Lithuanian Academic Libraries Network (LABT), 2009. http://vddb.library.lt/obj/LT-eLABa-0001:E.02~2009~D_20090408_085213-11247.
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The present Ph.D. thesis is the experimental and theoretical analysis of the femtosecond laser pulse induced damage processes in thin film dielectric coatings. Experimental investigations were performed by automated metrological facility designed for S-on-1 laser-induced damage threshold measurements. Femtosecond repetitive pulses (1 kHz) either at fixed 800 nm and 400 nm wavelengths or continuously tunable in 590 nm to 750 nm spectral range were used. The sensitivity of assembled metrological facility was sufficient to determine the influence of various deposition factors (process parameters and coating materials) on LIDT of optical coatings. Our experimental investigations on multi-layer ZrO2/SiO2, HfO2/SiO2, Ta2O5/SiO2, TiO2/SiO2 high reflection coatings and single-layer TiO2 have yielded several important results. To summarize: stepwise change of LIDT values was experimentally observed at the wavelength where two-photon absorption changes to three-photon absorption. This confirms that multiphoton absorption is one of the main damage mechanisms in femtosecond range. The multilayer coatings deposited by IAD and e-beam techniques on substrates having roughness of 0.64 nm or smaller showed similar LIDT values. Moreover, it was also confirmed that suppressing of standing wave electric field intensity at the outer layers of high refractive index improves the optical resistance of high reflectivity coatings also for femtosecond pulses. Furthermore, the model of the... [to full text]Pagrindinis šio darbo tikslas - eksperimentiškai ir teoriškai išnagrinėti fundamentinius bei technologinius veiksnius, apribojančius dielektrinių dangų optinį atsparumą pasikartojantiems femtosekundinės trukmės lazerio impulsams. Specialiai šiems tyrimams atlikti buvo sukurta automatizuota eksperimentinė įranga, kuri pagreitino pažeidimo slenksčio matavimus ir minimizavo žmogiškąjį faktorių. Darbo metu eksperimentiškai buvo tiriamos tiek vienasluoksnės TiO2, tiek ir didelio atspindžio koeficiento daugiasluoksnės ZrO2/SiO2, HfO2/SiO2, Ta2O5/SiO2 bei TiO2/SiO2 dangos, padengtos skirtingais būdais. Pirmą kartą eksperimentiškai pademonstruota, kad dėl daugiafotonės sugerties įtakos dielektrinių dangų pažeidimo slenkstis, tolydžiai keičiant femtosekundinių impulsų bangos ilgį, kinta šuoliškai. Kartu pademonstruotos ir teorinės šio rezultato prielaidos. Eksperimentiškai pademonstruota, kad didelio atspindžio koeficiento dangose stovinčiosios elektromagnetinės bangos pūpsnius „perstūmus“ į žemesnio lūžio rodiklio sluoksnius padidėja optinis atsparumas ir femtosekundinei lazerinei spinduliuotei. Taip pat eksperimentiškai buvo nustatyti įvairių dangų, dengtų jonapluoščio dulkinimo, elektronpluoščio nusodinimo su papildomu jonų tankinimu ir be jo technologijomis, pažeidimo slenksčiai įvairios trukmės ir įvairių bangos ilgių femtosekundiniams impulsams. Teoriškai išnagrinėtas vadinamojo S-į-1 pažeidimo tikimybės matavimo atvejis, kai lazerinės spinduliuotės erdviniai ir energetiniai... [toliau žr. visą tekstą]
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Mackey, Christopher Paul. "Laser calorimetric studies of optical absorption in all dielectric multilayer coatings." Thesis, Queen's University Belfast, 1991. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.334587.
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Yeh, Jen-Yu. "Electron-beam biased reactive evaporation of silicon, silicon oxides, and silicon nitrides /." Online version of thesis, 1991. http://hdl.handle.net/1850/11106.
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Badheka, Rita. "Novel routes to designer oxides and fluorides." Thesis, University of Surrey, 1999. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.301375.
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Raheem-Kizchery, Ayesha Rubiath. "Ceramic coatings for silica and sapphire optical waveguides for high temperature embedding and sensing." Thesis, This resource online, 1990. http://scholar.lib.vt.edu/theses/available/etd-09052009-040217/.
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Lehan, John Philip. "Microstructural investigations of optical coatings by backscattering spectrometry, electron diffraction, and spectrophotometry." Diss., The University of Arizona, 1990. http://hdl.handle.net/10150/184997.
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Backscattering spectrometry with MeV ⁴He ion beams is investigated as a tool for determining composition with applications to optical coatings. Equations for the compositional analysis of thin films are reviewed. The effect of nuclear charge screening on compositional analysis by MeV ⁴He beams is discussed and examples involving the lanthanide trifluorides illustrate the importance of this correction to avoid possibly erroneous conclusions about sample composition. High probe beam energy is also briefly discussed as a method of reducing the overlap of peaks in backscattering spectra which reduces the technique's accuracy. Complications such as non-Rutherford scattering cross sections for light elements are addressed and an example given. The application of backscattering spectrometry to the depth profiling of elemental constituents in thin films is discussed. It is found that the backscattering spectrum itself provides a reasonable depth profile; however, its depth resolution is limited by the energy resolution of the detection system and energy straggling of the probe beam in the solid. In addition, the depth profile suffers from considerable noise. A method is derived using the principle of maximum likelihood which allows hypothetical depth profiles to be tested and the effects of energy straggling and detection system resolution to be separated from the depth profile. Several examples involving two hypothetical depth profile models are presented. Finally, backscattering spectrometry is combined with scanning electron microscopy, transmission electron microscopy, electron diffraction, x-ray photoelectron spectroscopy, and spectrophotometry in a microstructural survey of hafnium dioxide optical coatings deposited by electron beam evaporation and ion-assisted deposition (IAD). It is found that hafnium dioxide films deposited at temperatures below 300°C are amorphous and exhibit a negative optical inhomogeneity. The refractive index as well as the inhomogeneity are strongly influenced by the oxygen present during film deposition. The inhomogeneity can be removed by IAD which also increases the refractive index of the film. In addition, low energy IAD is found to increase the refractive of the films without affecting the inhomogeneity. This is explained by the preferential sputtering of hydroxide from the growing film surface by the bombarding ions.
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Nygren, Kristian. "Magnetron Sputtering of Nanocomposite Carbide Coatings for Electrical Contacts." Doctoral thesis, Uppsala universitet, Oorganisk kemi, 2016. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-302063.
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Today’s electronic society relies on the functionality of electrical contacts. To achieve good contact properties, surface coatings are normally applied. Such coatings should ideally fulfill a combination of different properties, like high electrical conductivity, high corrosion resistance, high wear resistance and low cost. A common coating strategy is to use noble metals since these do not form insulating surface oxides. However, such coatings are expensive, have poor wear resistance and they are often applied by electroplating, which poses environmental and human health hazards. In this thesis, nanocomposite carbide-based coatings were studied and the aim was to evaluate if they could exhibit properties that were suitable for electrical contacts. Coatings in the Cr-C, Cr-C-Ag and Nb-C systems were deposited by magnetron sputtering using research-based equipment as well as industrial-based equipment designed for high-volume production. To achieve the aim, the microstructure and composition of the coatings were characterized, whereas mechanical, tribological, electrical, electrochemical and optical properties were evaluated. A method to optically measure the amount of carbon was developed. In the Cr-C system, a variety of deposition conditions were explored and amorphous carbide/amorphous carbon (a-C) nanocomposite coatings could be obtained at substrate temperatures up to 500 °C. The amount of a-C was highly dependent on the total carbon content. By co-sputtering with Ag, coatings comprising an amorphous carbide/carbon matrix, with embedded Ag nanoclusters, were obtained. Large numbers of Ag nanoparticles were also found on the surfaces. In the Nb-C system, nanocrystalline carbide/a-C coatings could be deposited. It was found that the nanocomposite coatings formed very thin passive films, consisting of both oxide and a-C. The Cr-C coatings exhibited low hardness and low-friction properties. In electrochemical experiments, the Cr-C coatings exhibited high oxidation resistance. For the Cr-C-Ag coatings, the Ag nanoparticles oxidized at much lower potentials than bulk Ag. Overall, electrical contact resistances for optimized samples were close to noble metal references at low contact load. Thus, the studied coatings were found to have properties that make them suitable for electrical contact applications.
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Muirhead, Ian T. "An evolution in molecular beam epitaxy (MBE) techniques for optical thin film coatings." Thesis, Heriot-Watt University, 1991. http://hdl.handle.net/10399/849.
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Martins, Edgar José Ferreira São Bento. "Application and characterization of graphene oxide coatings onto optical fibers for sensor development." Master's thesis, Universidade de Aveiro, 2016. http://hdl.handle.net/10773/16861.
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Mestrado em Engenharia MecânicaNos ultimos anos, o uso da bra otica cresceu consideravelmente, sendo os sensores uma das suas maiores aplica c~oes. Esta tecnologia tem diversas vantagens sobre os sensores convencionais tais como: imunidade a interfer^ encias eletromagn eticas, biocompatibilidade e elevada sensibilidade. No entanto, h a interesse cient co e industrial em melhorar o seu desempenho (sensibilidade, resolu c~ao do sensor e gama de trabalho), sendo o revestimento da bra otica com diversos materiais um dos procedimentos que poder a ser usado para alcan car esse objectivo. O oxido de grafeno e um derivado do carbono que resulta da exfolia c~ao da gra te. Este nanomaterial consiste em folhas semelhantes as do grafeno mas possui grupos funcionais de oxig enio que podem reagir f sica ou quimicamente com diversas esp ecies. No ^ambito desta disserta c~ao foram revestidas bras oticas com oxido de grafeno atrav es da deposi c~ao por camadas. Nos revestimentos variou-se o processo de deposi c~ao e o n umero de camadas. A caracteriza c~ao foi feita atrav es de espectroscopia de Raman, microscopia electr onica de varrimento e microscopia de for ca at omica. Para averiguar a integridade dos revestimentos imersos em solu c~ao aquosa, foram realizados testes de lix via c~ao. Os resultados da caracteriza c~ao dos revestimentos con rmam a presen ca de oxido de grafeno na superf cie da bra otica. Depois de garantir a qualidade dos revestimentos procedeu-se ao desenvolvimento e caracteriza c~ao dos sensores baseados em bra otica com revestimentos de oxido de grafeno. Foram testadas duas con gura c~oes diferentes baseadas em redes de Bragg uniformes e inclinadas. Os sensores foram testados sem e com revestimento a varia c~oes de ndice de refra c~ao, variando o procedimento de deposi c~ao do oxido de grafeno e o n umero de camadas. A corros~ao do ferro e um dos maiores problemas enfrentados pelos engenheiros. E a degrada c~ao gradual dos metais provocada por rea c~oes qu micas resultantes da intera c~ao do metal e o meio ambiente. Neste trabalho pretendeu-se, ainda, investigar a possibilidade do oxido de grafeno estabelecer liga c~oes qu micas com o ferro, e assim permitir detectar o fen omeno da corros~ao. Neste caso os sensores foram testados em solu c~oes de nitrato de ferro(III). Veri cou-se que h a altera c~ao das caracteristicas dos espetros das redes de Bragg quando s~ao imersos em diferentes solu c~oes, no entanto os resultados n~ao s~ao muito conclusivos quanto as diferen cas entre os procedimentos de deposi c~ao e ao n umero de camadas.
In the last years, the use of optical bers has grown considerably, being sensors one of the biggest applications. This technology has several advantages over conventional sensor such as: immunity to electromagnetic interferences, biocompatibility and high sensitivity. However, there is a scienti c and industrial interest to improve the sensor performance (sensitivity, resolution and working range). Coating the optical ber sensor with di erent materials is one proceeding that can be used to achieve this goal. Graphene oxide is a carbon derivative which results from the exfoliation of graphite. This nanomaterial consists in graphene like sheets with oxygen functional groups that can react physicaly or chemically with di erent species. In this work several optical bers samples were coated with GO through the layer by layer method. Two di erent proceedings were tested as the in uence of the number of of graphene oxide layers. The coating characterization was made through Raman spectroscopy, scanning electron microscopy and atomic force microscopy. To test the integrity of the coatings immersed in aqueous solutions, a leaching test was carried out. The results of the characterization con rm the presence of graphene oxide in the optical ber surface. After ensuring the quality of the graphene oxide coatings, it was carried out the development and characterization of optical ber based sensors with graphene oxide coatings. Were tested two di erent sensor con gurations, one based in uniform Bragg gratings and the other in tilted Bragg gratings. The sensors were tested without and with coating to refractive index variations, changing the proceeding to deposit the graphene oxide and the number of layers. Iron corrosion is one of the biggest problems faced by engineers. It is the gradual degradation of the metal by chemical reactions produced by the interactions of the metal with the environment. In this work, it was studied the possibility of the graphene oxide interact with the iron ion in order to detect the corrosion phenomenon. In this case, the sensors were tested in iron(III) nitrate solutions. It was veri ed that there are alterations of the Bragg gratings spectra characteristics when they were immersed in di erent solutions, however the results are not conclusive concerning the in uence of the coating proceeding used and the in uence of the number of layers.
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King, David Michael. "The optical properties of nanoscale coatings on particles fabricated by atomic layer deposition." Connect to online resource, 2008. http://gateway.proquest.com/openurl?url_ver=Z39.88-2004&rft_val_fmt=info:ofi/fmt:kev:mtx:dissertation&res_dat=xri:pqdiss&rft_dat=xri:pqdiss:3337114.
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Madiba, Itani Given. "Thermochromic properties of VO2 nano-coatings by inverted cylindrical magnetron sputtering." Thesis, University of the Western Cape, 2012. http://hdl.handle.net/11394/4381.
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>Magister Scientiae - MScVanadium dioxide (VO2) films have been known as the most feasible thermochromic nano-coatings for smart windows which self control the solar radiation and heat transfer for energy saving and comfort in houses and automotives. Such an attractive technological application is due to the fact that VO2 crystals exhibit a fast semiconductor-to-metal phase transition at a transition temperature TM of about 68°C, together with sharp optical changes from high transmitive to high reflective coatings in the IR spectral region. The phase transition has been associated to the nature of the microstructure, stoichiometry and some other surrounding parameters of the oxide. This study reports on the effect of the crystallographic quality controlled by the substrate temperature on the thermochromic properties of VO2 thin films synthesized by inverted cylindrical magnetron sputtering. Vanadium dioxide thin films were deposited on glass substrate, at various temperatures between 350 to 600 0C, deposition time kept constant at 1 hour. Prior the experiment, deposition conditions such as base pressure, oxygen pressure, rf power and target-substrate distance were carefully optimized for the quality of VO2 thin films. The reports results are based on AFM, XRD, RBS, ERDA and UV-VIS. The atomic force microscopy (AFM) was used to study the surface roughness of the thin films. Microstructures and orientation of grain size within the VO2 thin films were investigated by the use of X-ray diffraction technique. The stoichiometry and depth profiles of the films were all confirmed by RBS and ERDA respectively. The optical properties of VO2 were observed using the UV-Vis spectrophotometer.
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Maciulevičius, Mindaugas. "The Light Scattering in Optical Coatings and Laser Components in a Wide Spectral Range." Doctoral thesis, Lithuanian Academic Libraries Network (LABT), 2010. http://vddb.laba.lt/obj/LT-eLABa-0001:E.02~2009~D_20100204_101017-90059.
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This work describes the system for the light scattering measurements in a wide spectral range, which uses the light parametric oscillators and harmonic generators pumped with a nanosecond pulses and summarizes the research in various types of coatings on optical components and inside nonlinear optical crystals. The total scattering losses for the first time were characterized in the infrared region for a new promising in nonlinear optics LiInS2 and LiInSe2 crystals. It was shown that the laser scattering tomography, previously used for investigation of volume defects in semiconductor crystals, can be applied in the nonlinear optical quality control.Šiame darbe yra aptariama sklaidos matavimo sistema sukurta plačioje spektro srityje reikalingiems matavimams atlikti. Joje naudojami parametriniai šviesos generatoriai bei harmonikų generatoriai, kaupinami nanosekundinės trukmės impulsais, ir apibendinami sklaidos tyrimai, atlikti įvairių tipų optinėse dangose ir netiesiniuose optiniuose kristaluose, naudojant derinamojo bangos ilgio lazerinius impulsus. Pirmą kartą buvo ištirti naujų netiesinėje optikoje perspektyvių LiInS2 ir LiInSe2 kristalų sklaidos nuostoliai infraraudonojoje srityje. Taip pat parodyta, kad koherentinės sklaidos tomografijos metodas, anksčiau taikytas puslaidininkinių kristalų tūriniams defektams tirti, yra tinkamas ir netiesinėje optikoje naudojamų kristalų kokybės tyrimams.
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Nuru, Zebib Yenus. "Spectrally selective AlXOY/Pt/AlXOY solar absorber coatings for high temprature solar-thermal applications." Thesis, University of Western Cape, 2014. http://hdl.handle.net/11394/3365.
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Philosophiae Doctor - PhDThe limited supply of fossil hydrocarbon resources and the negative impact of CO2 emission on the global environment dictate the increasing usage of renewable energy sources. Concentrating solar power (CSP) systems are the most likely candidate for providing the majority of the renewable energy. For efficient photo-thermal conversion, these systems require spectrally selective solar absorber surfaces with high solar absorbance in the solar spectrum region and low thermal emittance in the infrared region. In this thesis, a spectrally selective AlxOy/Pt/AlxOy multilayer solar absorber was designed and deposited onto copper substrate using electron beam evaporation at room temperature. The employment of ellipsometric measurements and optical simulation was proposed as an effective method to optimize and deposit the multilayer solar absorber coatings. The optical constants measured using spectroscopic ellipsometry, showed that both AlxOy layers, which used in the coatings, were dielectric in nature and the Pt layer was semi-transparent. The optimized multilayer coatings exhibited high solar absorptance ~ 0.94±0.01 and low thermal emittance ~ 0.06 ± 0.01 at 82oC.The structural and optical properties of the coatings were investigated. It was found that the stratification of the coatings consists of a semitransparent middle Pt layer sandwiched between two layers of AlxOy. The top and bottom AlxOy layers were nonstoichiometric with no crystalline phases present. The Pt layer is in the fcc crystalline phase with a broad size distribution and spheroidal shape in and between the rims of AlxOy. The surface roughness of the stack was found to be comparable to the inter-particle distance. To study the thermal stability of the multilayer solar absorber coatings, the samples were annealed at different temperatures for different duration in air. The results showed changes in morphology, structure, composition, and optical properties depend on both temperature and duration of annealing. The XRD pattern showed that the intensity of Pt decreased with increasing annealing temperature and therefore, disappeared at high temperature. With increasing annealing temperature, an increase in the size of Pt particles was observed from SEM. The AlxOy/Pt/AlxOy multilayer solar absorber coatings deposited onto Cu substrate were found to be thermally stable up to 500oC in air for 2 h with good spectral selectivity of 0.951/0.09. At 600oC and 700oC, the spectral selectivity decreased to 0.92/0.10 and 0.846/0.11 respectively, which is attributed to the diffusion of Cu and formation of CuO and Cu2O phases. Long term thermal stability study showed that the coatings were thermally stable in air up to 450oC for 24 h. To elucidate the degradation mechanism beyond 500oC, HI-ERDA has been used to study depth-dependent atomic concentration profiles. These measurements revealed outward diffusion of the copper substrate towards the surface and therefore, the decrease in the constituents of the coating. Hence, to prevent copper from diffusing towards the coatings, a thin Tantalum (Ta) layer was deposited between the base AlxOy layer and the copper substrate.The effect of a thin Ta layer on the thermal stability of AlxOy/Pt/AlxOy multilayer solar absorber coatings was investigated. The Cu/Ta/AlxOy/Pt/AlxOy multilayer solar absorber coatings were found to be thermally stable up to 700oC in air for 2 h with good spectral selectivity of 0.937/0.10. At 800oC, the spectral selectivity decreased to 0.870/0.12, which is attributed to the diffusion of Cu and formation of CuO phase. The formation of CuO phase was confirmed by XRD, EDS and Raman spectroscopy. Long term thermal stability study showed that the coatings were thermally stable in air up to 550oC for 24 h. Therefore, the Cu/Ta/AlxOy/Pt/AlxOy spectrally selective solar absorber coatings can be used for high temperature solar-thermal applications.
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Skjonnemand, Karl. "The optical and structural characterisation of ultra-thin films." Thesis, Cranfield University, 2000. http://dspace.lib.cranfield.ac.uk/handle/1826/10739.
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Chloride, bromide, pyridinium and quinolinium homologues of 4-(N- hexadecylpyridinium-4-ylmethylidene-amino)-2,6-dichlorophenolate have been investigated in solution, Langmuir and Langmuir-Blodgett films. Techniques including spectroscopy, surface potential measurement, quartz crystal microbalance, surface plasmon resonance, atomic force microscopy, reectometry and X-ray diffraction have been used to characterise these molecular systems. In solution, solvatochroism was observed and Benisi-Hildebrand analysis revealed dimeric aggregation. Langmuir monolayers were compressed at the air/water interface and chromophore rotation was observed by surface potential measurement. Langmuir- Blodgett monolayers showed lm-thickness dependence on the deposition-pressure. Monolayer thicknesses between 6-24Ä were measured using SPR and molecular areas between 40-l25Ä2 were measured using a quartz crystal microbalance. Both the molecular/s/area)and monolayer thicknesses were deposition-pressure dependent. The high tilt phases were visually distinguishable from the low tilt phases using atomic force microscopy, The compounds showed phase behaviour that was predominantly alike for the bromide and chloride homologues but different for the pyridinium and quinolinum homologues. Multilayer Y-type films of the merocyanine dyes were analysed using reectometry and deposition-pressure dependent thicknesses were found. Alternate layer structures of NLO-active hemicyanine amphiphiles were used to achieve homogeneous. orientation ordering using active and inactive spacer layers. Ordering was achieved but the optical efficiency was reduced by high proportions of inactive material and interlayer dipole formation. Double chained hemicyanine molecules were used to form Z-type structures and subsequent layers were found to significantly interdigitate. Different chain lengths were found to interdigitate by the length of the shortest chain. Gas detection experiments were undertaken on the quinolinium, dichloro merocyanine using three optical geometries. The absorption method showed slow switching and poor sensitivity. The Kretschmann SPR geometry showed high sensitivity and rapid switching. The grating SPR geometry showed rapid switching but was less sensitive than the ATR method. Protonation of the monolayers was investigated using hydrochloric acid gas, acetic acid vapour and stearic acid immobilised within the lm.
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Anooshehpour, Farid. "Optical emission spectroscopy as a process-monitoring tool in PECVD of amorphous carbon coatings." Master's thesis, Université Laval, 2016. http://hdl.handle.net/20.500.11794/27142.
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Dans ce projet de recherche, le dépôt des couches minces de carbone amorphe (généralement connu sous le nom de DLC pour Diamond-Like Carbon en anglais) par un procédé de dépôt chimique en phase vapeur assisté par plasma (ou PECVD pour Plasma Enhanced Chemical Vapor deposition en anglais) a été étudié en utilisant la Spectroscopie d’Émission Optique (OES) et l’analyse partielle par régression des moindres carrés (PLSR). L’objectif de ce mémoire est d’établir un modèle statistique pour prévoir les propriétés des revêtements DLC selon les paramètres du procédé de déposition ou selon les données acquises par OES. Deux séries d’analyse PLSR ont été réalisées. La première examine la corrélation entre les paramètres du procédé et les caractéristiques du plasma pour obtenir une meilleure compréhension du processus de dépôt. La deuxième série montre le potentiel de la technique d’OES comme outil de surveillance du procédé et de prédiction des propriétés de la couche déposée. Les résultats montrent que la prédiction des propriétés des revêtements DLC qui était possible jusqu’à maintenant en se basant sur les paramètres du procédé (la pression, la puissance, et le mode du plasma), serait envisageable désormais grâce aux informations obtenues par OES du plasma (particulièrement les indices qui sont reliées aux concentrations des espèces dans le plasma). En effet, les données obtenues par OES peuvent être utilisées pour surveiller directement le processus de dépôt plutôt que faire une étude complète de l’effet des paramètres du processus, ceux-ci étant strictement reliés au réacteur plasma et étant variables d’un laboratoire à l’autre. La perspective de l’application d’un modèle PLSR intégrant les données de l’OES est aussi démontrée dans cette recherche afin d’élaborer et surveiller un dépôt avec une structure graduelle.The production of amorphous carbon coatings or as commonly known as diamond like carbon (DLC) coatings, using the plasma enhanced chemical vapor deposition (PECVD) method is studied through optical emission spectroscopy (OES) as a plasma diagnostic technique and the partial least square regression (PLSR) statistical method. The objective is to establish a model to predict DLC properties independent of reactor-related parameters, in order to be used in any other similar deposition process. Therefore the model correlates the deposited coating properties to plasma parameters derived from OES. The OES derived data carries a variety of information about plasma characteristics. The relative spectral line intensities of CH and atomic H to specific Ar lines were employed as a probe of their concentrations according to actinometry method. The full width at half maximum of atomic H was also employed. This method can be used as a probe of gas temperature via Doppler broadening effect. The DLC coatings were characterized using profilometry for thickness and stress measurements and Auger electron spectroscopy (AES) for structural analysis. There were two series of PLSR analysis carried out: The first analysis studies the correlation between process parameters and plasma characteristics, as derived by OES, for a better understanding of the plasma deposition process. The second analysis shows how the OES can be used for prediction of coating properties and for process monitoring. According to the results, the OES data (especially the parameters that are related to the concentration of atomic hydrogen and CH species) are able to represent some parts of process parameters (plasma power, mode and pressure) in a statistical model that is designed for predicting DLC coating properties. In other words, this means that this plasma diagnostic technique can be employed for in-situ monitoring of growing DLC coating properties, instead of using process parameters, which are related to the deposition reactor and may vary from one system to another. The perspective of using the OES data and the PLSR analysis in designing and monitoring a structurally gradient DLC coating is also discussed.
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Chiao, Shu-Chung 1958. "The influence of stoichiometry on the properties of titanium oxide films for optical coatings." Diss., The University of Arizona, 1996. http://hdl.handle.net/10150/290580.
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This study investigates various properties of titanium oxide thin films. The samples are prepared by electron-beam evaporation of the Ti₂O₃ material in an oxygen environment. Papers about the vaporization study of the titanium-oxygen system are reviewed; special attention is paid to the congruent vaporization in the titanium-oxygen system. The occurrence of congruent vaporization in our coating system is discussed. The compositions of the films are identified by Rutherford Backscattering Spectrometry. The effect of water vapor and the substrate temperature on the oxygen contents in RBS measurements is discussed. The optical properties of the samples are measured. With the spectrophotometric measurements, the methods for deriving the optical constants of transparent and opaque films are developed. The absorption of the TiO₂ film is investigated, and the corresponding mechanisms are discussed. The envelope method is employed to find the optical band gap of the TiO₂ film. The electrical resistivity of the titanium oxide films are measured with the four-point probe method, and the phenomenon of metal to insulator transition is demonstrated. The tensile stresses in our titanium oxide films are examined with a Nomarski microscope. The grain boundary model is adopted to explain the influence of thickness and oxygen content on the stresses development in thin film. Molecular dynamics simulation is used to study the structure and the thermal expansion of titanium dioxide rutile.
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Gifford, Erika Lea. "Sensitivity control of optical fiber biosensors utilizing turnaround point long period gratings with self-assembled polymer coatings." Diss., Virginia Tech, 2008. http://hdl.handle.net/10919/28201.
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Biosensors have a multitude of important applications in basic research, environmental monitoring, biodefense, and medicine. This research aims to show that Ionic Self-Assembled Multilayers (ISAMs) adsorbed on Long Period Gratings (LPGs) can serve as a highly sensitive, robust, inexpensive optical-based biosensor platform. The ISAM technique is a layer-by-layer deposition method that builds nanometer-thick films based on the principle of Coulomb attraction between oppositely charged polyelectrolyte solutions while LPGs cause strong attenuation bands that enable an optical fiber to be extremely sensitive to changes in the surrounding environment. LPGs have been shown to be highly sensitive to the adsorption of nanoscale self-assembled films on the optical fiber cladding surface. In this work, we utilize Turnaround Point (TAP) LPGs, which possess even greater sensitivity than standard LPGs. This thesis focuses on evaluation of approaches to increasing the sensitivity of the sensor platfom, implementation of a biosensor for detection of several biomolecules, and preliminary evaluation of the potential for pH sensing.
For a thin-film coated TAP LPG, we have demonstrated that shifts in the transmitted light intensity at the resonant wavelength of the LPG can result from the variation in film thickness and/or refractive index. We have observed decreases in intensity as large a 7 dB for one bilayer of ISAM film (~1 nm), which corresponds to an 80% decrease in the transmitted light intensity at the resonant wavelength. We have also shown that the sensitivity of the TAP LPG sensor can be increased by implementing nm-thick ISAM films that have a refractive index greater than silica. Furthermore, it is shown that incorporation of silica nanoparticles into the ISAM films significantly increases sensitivity through increased surface area and thickness.
The biotin-streptavidin system was used as a model for implementaion and optimization of the ISAM-coated TAP LPG biosensor platform. Through evaluation of various biotin derivatives to maximize the amount functionalized onto the ISAM film, optimization of the ISAM film properties, and use of LPGs designed for higher sensitivity, the minimum detectable concentration of streptavidin was decreased from 0.0125 mg/ml to 12.0 ng/ml. The biosensor platform was then tested on prostate specific antigen (PSA), which is used as a clinical marker for early diagnosis of potential prostate cancer. Using a direct crosslinking approach of the monoclonal antibody to PSA into the ISAM film, a sensitivity level of 11.64 ng/ml PSA was obtained through combined optimization of the ISAM film and antibody surface coverage. Finally, the potential of ISAM TAP LPGs as pH sensors was examined based on the pH dependent swelling of ISAM films.Ph. D.
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Li, Chenghong. "Inorganic-Organic Sol-Gel Derived Hybrid Materials as Abrasion Resistant Coatings." Diss., Virginia Tech, 1999. http://hdl.handle.net/10919/39013.
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Inorganic-organic hybrid materials have been developed using sol-gel reactions of a trialkoxysilylated organic compound and a metal or semi-metal alkoxide and applied as coatings on polymeric or metallic substrates. Many of these coatings have demonstrated good to excellent abrasion resistance.
Abrasion resistant coatings were prepared by hydrolysis and condensation of mixtures of a triethoxysilylated diethylenetriamine (f-DETA), tetramethoxysilane (TMOS), water and an alcohol in the presence of an acid catalyst (a one-step hydrolysis approach). The influences of many formulation and processing variables on the gelation time, optical properties, hardness and abrasion resistance were investigated. An aminolysis mechanism was also proposed to explain the adhesion between sol-gel derived coatings and polycarbonate substrates promoted by a 3-aminopropyltriethoxysilane (3-APS) primer. FT-IR, GPC, 1H and 13C NMR, XPS experiments were conducted to support this mechanism.
The f-DETA/TMOS system is essentially a binary system of an alkyltriethoxysilane (T) and a tetraalkoxysilane (Q). At pH 0-2 and pH 4-5, the relative condensation reactivities of the T and Q species in this system were compared using 29Si NMR spectroscopy. After thermal curing, 13C or 29Si solid state NMR spectroscopy was used to estimate the extent of hydrolysis of the urea linkages in f-DETA, the concentration of residual alkoxysilane groups, and the extent of condensation for both T and Q species. The dependence of the morphology of f-DETA/TMOS gels on the pH and the water concentration was also investigated using AFM, SEM and SAXS.
Many other trialkoxysilylated organic compounds containing urea, urethane, epoxy and siloxane linkages were also synthesized and utilized to prepare abrasion resistant coatings via a one-step hydrolysis approach, a two-step hydrolysis approach or a moisture-curing approach. Coatings derived from many of these systems or approaches demonstrated abrasion resistance comparable to that of the f-DETA/TMOS coating. Thin coatings were also derived from cubic octasilicate monomers via hydrosilylation or sol-gel reactions. These coatings were very transparent but unfortunately lacked abrasion resistance.Ph. D.
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Coakley, Martha. "Growth and Optical Characterization of Zinc Oxide Nanowires for Anti-reflection Coatings for Solar Cells." PDXScholar, 2011. https://pdxscholar.library.pdx.edu/open_access_etds/290.
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The optical properties of solar cells greatly affect their efficiencies. Decreasing the broadband and directional reflectance of solar cells increases the solar irradiance transmitted and absorbed by the cell, thereby increasing the production of electron-hole pairs. Traditional optical enhancements such as light trapping and anti-reflection coatings reduce the reflectance of silicon at an optimized wavelength and angle of incidence. They do not perform as well at high angles of incidence or over the broadband solar spectrum. Theoretical studies suggest that layers with a suitable gradient-index of refraction can create both a broadband and directional anti-reflective coating. Through their variations in height and tapered growth, Zinc oxide (ZnO) nanowires can create a gradient index anti-reflection coating. ZnO is a wide-band gap semiconductor that is non-absorbing over most of the solar spectrum. With low cost, low temperature techniques, ZnO nanowires can be grown with a variety of morphologies. ZnO nanowires were grown by aqueous chemical growth and by electrodeposition on silicon to create a gradient-index anti-reflective coating for solar cell applications. The nanowire arrays were characterized using SEM images, goniometer scattering measurements, and integrating sphere total reflectance measurements. ZnO nanowires grown by aqueous chemical growth on silicon had average diameters between 60 nm and 100 nm and average lengths between 800 nm and 1100 nm. The nanowires had vertical alignment. They exhibited relatively small diffuse reflectivities and relatively large specular reflectivities. ZnO nanowires grown by electrodeposition had greater variances in length and diameter, with average diameters between 85 nm and 180 nm and average lengths between 500 nm and 1200 nm. Electrodeposited ZnO nanowires were randomly arrayed and exhibited relatively large diffuse reflectivities and relatively small specular reflectivities. Total reflectance measurements showed that all nanowire arrays reduced the broadband reflectance of silicon. Smaller nanowire arrays outperformed the larger crystal growths. A five-fold decrease in the broadband reflectance of silicon was obtained from both vertical and randomly oriented nanowire arrays. The reflectances were constant for angles of incident below 35°. Measurements at angles of incidence greater than 35° are required to determine whether ZnO nanowires can perform as directional anti-reflective coatings and whether the morphology of the nanowires affects the directional reflectances.
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F, SARRI. "Optical microstructuring of alkali metal nanoparticle coatings on porous silica substrates induced by Bessel beam." Doctoral thesis, Università di Siena, 2019. http://hdl.handle.net/11365/1075534.
Full textAbstract:
The ability to control atomic adsorption/desorption processes by light as well as nanoparticle growth
on proper substrates is nowadays recognized as a promising technique in nanotechnology. This
subject is a part of a rising area of research devoted to the development of micro and nanophotonic
devices, sensors, metamaterials. The experimental work in this thesis aims at obtaining ordered
microstructures exploiting atomic desorption phenomena such as LIAD (Light Induced Atomic
Desorption). The suitable substrates consist in nanoporous silica matrices sealed inside cells and
exposed to alkaline atom vapor. A Gaussian beam generated by a laser, transformed in Bessel beam
by a conical shape lens, has been used as desorption light: in such way, the nanoparticles are created
on the pores and they are arranged following the Bessel beam profile, obtaining then the order
microscopic structure. More efficiently a coating of alkali metal nanoparticles has been grown on the
porous substrate due to LIAD induced by a Hg lamp and then the atomic desorption induced by a
Bessel beam has been responsible for the redistribution of the generated nanoparticles in the
micrometric concentric ring structure following the beam profile. The experiments have been
performed using different alkaline atom vapors, moreover porous silica samples with different pore
size and lasers with different wavelengths have been used.
During the work, the experimental setup and procedure have been optimized, evaluating the best
conditions for obtaining a well defined structure, in particular as regards the power emitted by the
desorbing lasers and the lighting time intervals for the porous silica samples. Through adjustments to
these parameters multiple, overlapping or side-by-side, illuminations, without incurring erasing
phenomena, have been possible thus creating complex structures.
The structures thus obtained, whether simple or complex, act as micrometric masks made out of
nanoparticles, and they are persistent and reversible. These masks can be detected by illuminating
them with laser light and observing the ring-shaped pattern produced by diffraction.
The generated structures have been systematically analyzed verifying the effective formation of the
nanoparticles by detection of their absorption spectra, observing the microstructures under a
microscope and recording them with a CCD camera. By an image analysis software, the concentric ring
pattern, corresponding to a 2D quasi-Bessel function, has been studied, evaluating the spacing ring
distance from its Fourier transform using the FFT algorithm; in this way, the relationship between the
characteristics of the Bessel beam, the wavelength of the radiation and the physical characteristics of
the conical lens have been verified. Also, images of the ring-shaped pattern obtained by diffraction
have also been registered, in order to estimate the contrast with the background and its persistence
on the sample.
The experimental results on this thesis suggest a new technique for the laser structuring of alkali metal
nanoparticles in ordered patterns on micrometric scale resolution promising for many applications in
all-optical photonic devices.
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Tveten, Erlend Grytli. "Optical coatings for enhancement of the longitudinal Magneto-optic Kerr Effect from magnetic ultra-thin films." Thesis, Norges teknisk-naturvitenskapelige universitet, Institutt for fysikk, 2011. http://urn.kb.se/resolve?urn=urn:nbn:no:ntnu:diva-13266.
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The effect of optical coatings on the longitudinal magneto-optic Kerr effect response from 10 nm thin films of permalloy (Ni84Fe16) has been studied. Enhancement of the magneto-optic Kerr effect signal contrast of a factor 1.76 has been observed for P- polarized incident light on a trilayer configuration of aluminium, magnesium fluoride, and permalloy. A quadrilayer structure where the trilayer is overcoated with zinc sulphide enhances the signal contrast by a factor 4.05 for P-polarized light. The enhancement is also observed for S-polarized light, and is shown to be reproducible using nickel as the magnetic material and gold instead of aluminium.The experimental data are compared to a simplified theoretical model where the electric field components are calculated using a 4 x 4 matrix algorithm. The model is found to be inadequate in predicting the longitudinal magneto-optic Kerr effect response from complex multilayer structures. This is believed to be due to a simplification in the model disregarding the phase factors of the different components reflected off the multilayered samples.
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Shestakov, A. F. "Telomeres of Tetrafluoroethylene - Advanced Materials to Create Superhydrophobic Coatings and Optical Fiber with Low Attenuation Coefficient." Thesis, Sumy State University, 2013. http://essuir.sumdu.edu.ua/handle/123456789/35479.
Full textAbstract:
The paper describes formation of telomers of tetrafluoroethylene (TFE), which are very interesting in-termediate materials of different purposes, by radiation polymerization. In some cases there are formed long chained oligomers suitable for creation of superhydrophobic coatings. In such systems formation of gels is observed under low TFE content. Quantum chemical analysis allows to reveal the factors that are responsible for this phenomenon. In the case of solvents with appropriate cyclic structure, short chain oli-gomers, which have low C-H bonds content, are raw materials for fluoropolymers suitable for manufactur-ing optical fibers. The work is aimed to predict which types of materials are formed under polymerization conditions. For these purposes the generalized Polany-Semenov rule is used. Its parameters found by DFT calculations can be recommended for practical applications in the molecular design of new fluorine-containing polymers.
When you are citing the document, use the following link http://essuir.sumdu.edu.ua/handle/123456789/35479
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Rusli. "Optical and luminescence properties of hydrogenated amorphous carbon." Thesis, University of Cambridge, 1996. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.326704.
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LOPEZ, ISCOA PABLO. "Design, processing and characterization of glass fibers and coatings for healthcare industries." Doctoral thesis, Politecnico di Torino, 2019. http://hdl.handle.net/11583/2725389.
Full textAbstract:
In this PhD, several bioactive phosphate glasses doped with erbium ions (Er3+) were synthesized and characterized in order to develop new bioactive fiber sensors for medical diagnostics and therapeutics in healthcare applications.
Firstly, Er3+-doped phosphate glasses within the glass system P2O5-SrO-Na2O were fabricated using the melt-quenching technique. The glasses were prepared with different compositions and analyzed to understand the impact of the addition of Al2O3, TiO2 or ZnO on the thermal, structural and luminescence properties of the glasses. The results showed that with the addition of Al2O3 and TiO2 the phosphate network became more connected, whereas the addition of ZnO did not modify the optical, thermal and structural properties but it led to an enhanced fluorescence emission as compared to the other glasses.
Secondly, glass-ceramics (GCs) were processed by heat-treating the glasses to induce in-situ crystal growth. The effect of the crystallization on the properties of phosphate glasses containing Al2O3, TiO2 or ZnO was investigated. The structural, optical, and spectroscopic characterization allowed assessing the occurrence and properties of the Er3+-doped crystals in the glasses. Different crystal phases were obtained depending on the glass composition but Sr(PO3)2 was identified in all the glasses. Moreover, the surface crystallization of the GCs was increased along with the duration of the heat treatment. However, the site of the Er3+ ions was not strongly affected by the heat treatment except for the reference GC, where an increase of the luminescence properties was observed after the heat treatment probably due to the incorporation of Er3+ ions into the crystals.
Thirdly, particles-containing glasses were prepared using the direct doping method. A series of different Er3+-doped Al2O3, TiO2, ZnO and ZrO2 nano- and microparticles were synthesized using soft chemistry and then were added to phosphate-based glass batches prior to and after the melting. The survival and dispersion of the particles were optimized in order to increase the luminescence properties of the glasses. As evidenced by the morphological and compositional analyses, the Er3+ ions diffused from the particles to the glass matrix and no improvement of the spectroscopic properties was observed. A large amount of Er3+-doped particles were dissolved into the glasses probably due to the high temperatures achieved during the melting. As an alternative, glasses with different composition and lower melting temperatures were tested.
The last part of the project was the production and characterization of a multimode optical fiber made from phosphate-based glasses. The core composition was 0.25 Er2O3 – 97.25 (0.5 P2O5 – 0.4 SrO – 0.1 Na2O) – 2.5 ZnO, while the cladding composition was 98.25 (0.5 P2O5 – 0.4 SrO – 0.1 Na2O) – 1.75 ZnO. The cladding component was processed using the rotational casting technique, and the preform was successfully drawn into an optical fiber. This novel
optical fiber was found to be able to allow in-line monitoring of the fiber dissolution in H3PO4 and in simulated body fluid (SBF) solution. Bioactivity of the fiber was also assessed by the formation of a hydroxylapatite layer at the surface of the fiber after 4 weeks of immersion in SBF solution at room temperature.
In this thesis, a bioactive fiber sensor able to monitor its optical properties and in vitro reactivity was reported. This research activity demonstrates as a proof of principle the idea of tracking the bio-response of a bioactive optical fiber “in vivo”.
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Grosso, David. "Nanoparticles of scandium oxide, zirconium oxide and hafnium oxide in alcoholic medium, used for high index optical coatings at 351nm." Thesis, University of Surrey, 1998. http://epubs.surrey.ac.uk/804420/.
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Eroglu, Huseyin Cuneyt. "Design Of Reflective &." Master's thesis, METU, 2009. http://etd.lib.metu.edu.tr/upload/2/12611057/index.pdf.
Full textAbstract:
In order to improve the efficiency of various optical surfaces, optical coatings are used. Optical coating is a process of depositing a thin layer of a material on an optical component such as mirror or lens to change reflectance or transmittance.
There are two main types of coatings namelyreflective and antireflective (AR) Coatings. Reflective and antireflective coatings have long been developed for a variety of applications in all aspects of use
for optical and electro-optical systems in telecommunications, medicine, military products and space applications. In this thesis, the main properties of reflective and antireflective coatings, the thin film deposition techniques, suitable coating materials for space applications, space environment effects on coating materials and coating design examples which are developed using MATLAB for space applications will be discussed.
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Murphy, Neil Richard. "Reactive sputtering of mixed-valent oxides: a route to tailorable optical absorption." University of Dayton / OhioLINK, 2015. http://rave.ohiolink.edu/etdc/view?acc_num=dayton1427889137.
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