Dissertations / Theses: 'Liquid crystal lenses design'

1

Ashraf, Mujahid Al Islam. "Design and development of liquid crystal lenses." Australasian Digital Thesis Program, 2006. http://adt.lib.swin.edu.au/public/adt-VSWT20061117.145625.

Full text

Abstract:

Thesis (MEng) - Swinburne University of Technology, Faculty of Engineering and Industrial Sciences, Centre for Micro-Photonics, 2006.
A thesis submitted for the degree of Master of Engineering, Centre for Micro-Photonics, Faculty of Engineering and Industrial Sciences, Swinburne University of Technology, 2006. Typescript. Includes bibliographical references (p. 74-77).

APA, Harvard, Vancouver, ISO, and other styles

2

Ashraf, Mujahid Al Islam, and n/a. "Design and development of liquid crystal lenses." Swinburne University of Technology. Faculty of Engineering and Industrial Sciences, 2006. http://adt.lib.swin.edu.au./public/adt-VSWT20061117.145625.

Full text

Abstract:

The use of optics in the fields of nano-technology, telecommunication and medicine has been growing exponentially in recent years. Application of liquid crystals within optics has been a growing trend from flat screen displays to variable focus lenses in a digital versatile discs. One area of the recent developments within optics has been the development of two-photon fluorescence microscopy and high-density three-dimensional optical data storage. In such applications, where a light beam has to be focused deep within the volume of bulk media, aberrations are introduced. The most dominant aberration is spherical aberration which results from the mismatch in refractive indices of the immersion and recording media. The aim of this thesis is to design a liquid crystal lens for dynamic tube length compensation of the spherical aberration. Liquid crystal phase plates are used in everyday liquid crystal displays (LCDs) such as mobile phones and calculators. The technologies required to manufacture a liquid crystal phase plate are well understood. However, an application like three-dimensional data storage requires different properties in the liquid crystal phase plate, which are investigated in this thesis. To fabricate our liquid crystal phase plate we used ZLI-5049-000 from MERCK as the liquid crystal medium, with poly-vinyl alcohol (PVA) and Indium Tin Oxide (ITO) providing the insulating and conducting layers, respectively. It has been demonstrated that vacuum vapour deposition can be used to coat a glass substrate with ITO. However, in order for the ITO coating to be conductive a method is developed where the substrate is heated to 300oC before, during and after the coating. Similarly, a method has been developed for producing a uniform 10 μm coating of PVA on top of the ITO. In order to produce a liquid crystal lens with the properties required to compensate for spherical aberration an investigation into the properties of the liquid crystals is first conducted. A liquid crystal phase plate described in chapter 3 is characterised to determine the effect of the rubbing direction of the insulating layer and the effective refractive index change with applied voltage. It has been demonstrated that an effective change in refractive index of 0.11 can be achieved with 30 volts applied across the ITO electrodes. Based on the characterisation of the liquid crystal phase plate four different liquid crystal lens designs have been proposed and tested. The lens designs are based upon convergent and divergent lenses with different refractive index lens substrates. It is determined that a liquid crystal lens with a divergent lens substrate with a refractive index of 1.785 can be used to effectively compensate for spherical aberration. This has been confirmed experimentally by using the liquid crystal lens in a two-photon confocal microscope and measuring a increase in detected intensity at a depth below the surface of a sample. The research conducted in this thesis shows the ability to dynamically compensate for spherical aberration introduced by a mismatch in the refractive indices between the immersion and sample mediums. It has also been demonstrated that new methods for fabricating the conductive and insulating layers are suitable for producing a liquid crystal lens. A liquid crystal lens based on the research in this thesis could be used in three-dimensional data storage or microscopy applications.

APA, Harvard, Vancouver, ISO, and other styles

3

Williams, Geoffrey. "Electrically controllable liquid crystal Fresnel lenses." Thesis, Durham University, 1991. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.303875.

Full text

APA, Harvard, Vancouver, ISO, and other styles

4

Lu, Jiahui. "Designing wavefront sensors from liquid crystal microlenses." Thesis, University of Cambridge, 2014. https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.707989.

Full text

APA, Harvard, Vancouver, ISO, and other styles

5

Valley, Pouria. "FLAT LIQUID CRYSTAL DIFFRACTIVE LENSES WITH VARIABLE FOCUS AND MAGNIFICATION." Diss., The University of Arizona, 2010. http://hdl.handle.net/10150/145737.

Full text

Abstract:

Non-mechanical variable lenses are important for creating compact imaging devices. Various methods employing dielectrically actuated lenses, membrane lenses, and liquid crystal lenses were previously proposed [1-4]. In This dissertation the design, fabrication, and characterization of innovative flat tunable-focus liquid crystal diffractive lenses (LCDL) are presented. LCDL employ binary Fresnel zone electrodes fabricated on Indium-Tin-Oxide using conventional micro-photolithography. The light phase can be adjusted by varying the effective refractive index of a nematic liquid crystal sandwiched between the electrodes and a reference substrate. Using a proper voltage distribution across various electrodes the focal length can be changed between several discrete values. Electrodes are shunted such that the correct phase retardation step sequence is achieved. If the number of 2πzone boundaries is increased by a factor of m the focal length is changed from f to f/m based on the digitized Fresnel zone equation: f = rm²/2mλ, where r(m) is mth zone radius, and λ is the wavelength. The chromatic aberration of the diffractive lens is addressed and corrected by adding a variable fluidic lens. These LCDL operate at very low voltage levels (±2.5V ac input), exhibit fast switching times (20-150 ms), can have large apertures (>10 mm), and small form factor, and are robust and insensitive to vibrations, gravity, and capillary effects that limit membrane and dielectrically actuated lenses. Several tests were performed on the LCDL including diffraction efficiency measurement, switching dynamics, and hybrid imaging with a refractive lens. Negative focal lengths are achieved by adjusting the voltages across electrodes. Using these lenses in combination, magnification can be changed and zoom lenses can be formed. These characteristics make LCDL a good candidate for a variety of applications including auto-focus and zoom lenses in compact imaging devices such as camera phones. A business plan centered on this technology was developed as part of the requirements for the minor in entrepreneurship from the Eller College of Management. An industrial analysis is presented in this study that involves product development, marketing, and financial analyses (Appendix I).

APA, Harvard, Vancouver, ISO, and other styles

6

Li, Liwei. "High quality liquid crystal tunable lenses and optimization with floating electrodes." Thesis, Kent State University, 2014. http://pqdtopen.proquest.com/#viewpdf?dispub=3618874.

Full text

Abstract:

In addition to the display application, Liquid Crystals (LC) can be very useful in other applications such as beam steering, tunable lenses, etc.

Electro-optical LC tunable lenses have been considered as an alternative to conventional glass lenses because of their ability to change their focal length with the application of a control voltage, as well as small size and weight and low power consumption, fast speed, etc. They have a great potential in many applications such as: imaging systems of compact cameras, eye correction, and 3D display systems. So far, while many LC lens designs have been published, high quality performance has been only mentioned in very few papers; also, the level of details in those work is less than what is required to have an accurate evaluation of the performance as well as how it could be improved.

Therefore, the main goal of the work in this dissertation is designing high quality or near diffraction limited LC tunable lenses. We will not only introduce our design concepts and considerations, but also demonstrate fine details about the fabrication and evaluations. More importantly, we will use both simulation and experimental approaches for fully understanding the fundamental limiting factors affecting LC lenses. Consequently, we will introduce how they could be optimized and demonstrate the improved performance. In addition, there will be work addressing the concerns about speed, optical power, and off-axis performance.

The outline of the dissertation is given as follows, and each chapter has its own focus: In chapter 2, we will review the background of tunable LC lenses, introduce our design, and evaluate its performance in details; in chapter 3, we will investigate the physical limitations and fundamental factors affecting LC lens performance with both simulation and experimental results; in chapter 4, we will introduce the optimized design and demonstrate the improved performance; in chapter 5, we will introduce a multi-cell approach to improve its off-axis imaging performance and achieve a higher optical power, while keeping the fast switching speed; in chapter 6, we will discuss the phase reset methods to achieve higher optical power and fast response; finally in the last chapter, we will make the conclusion and summary. Also, there are four appendices in which we show the detailed LC lens fabrication process, complete optical characterization methods, simulation methods used in this dissertation work and the core Matlab codes, respectively.

APA, Harvard, Vancouver, ISO, and other styles

7

Li, Liwei. "High quality Liquid Crystal tunable lenses and optimization with floating electrodes." Kent State University / OhioLINK, 2013. http://rave.ohiolink.edu/etdc/view?acc_num=kent1385335287.

Full text

APA, Harvard, Vancouver, ISO, and other styles

8

Sova, Oleksandr. "Theoretical and experimental study of tunable liquid crystal lenses : wavefront optimization." Doctoral thesis, Université Laval, 2020. http://hdl.handle.net/20.500.11794/67581.

Full text

Abstract:

Adaptive optical systems have applications in various domains: imaging (zoom and autofocus), medicine (endoscopy, ophthalmology), virtual and augmented reality. Liquid crystal-based lenses have become a big part of adaptive optics industry as they have numerous advantages in comparison with traditional methods. Despite significant progress made over the past decades, certain performance and production limitations still exist. This thesis explores ways of overcoming these problems, considering two types of tunable lenses: liquid crystal lens using dielectric dividing principle and modal control lens.The introduction of this thesis presents the theory of liquid crystals and adaptive lenses, addressing existing liquid crystal lenses as well.In the first and second chapters of this work we demonstrate the results of theoretical modeling of double dielectric optically hidden liquid crystal lens design. We have studied the influence of geometrical parameters, such as thickness of liquid crystal cell, shape and dimensions of dielectrics forming the optically hidden layer, on the optical power of the lens. The dependences of optical power on the relative permittivity and conductivity of dielectrics were obtained. The behavior of such a lens in the presence of temperature variation was analyzed. We have further extended the concept of hidden dielectric layer to exploration of microstructures. Two systems of microlenses and microprisms have been simulated. The comparison of optical phase modulation dependence on spatial frequency of microstructures was obtained. Deviations from ideal wavefronts were evaluated in both cases. We also compared proposed designs with a standard interdigital electrode approach. Suggested devices could be used for continuous light steering or as tunable microlens arrays. In the third and fourth chapters we present our studies of tunable lenses based on modal control principle. We verified simulation results by comparing them with experimentally obtained dependences of optical power and root mean square spherical aberrations. We have explored the following modifications of conventional modal control lens: 1) additional powered ring electrode; 2) floating disk electrode; 3) combination of the first two cases. The influence of each modification was studied and explained. Simulation results showed that using the combination of additional electrodes along with optimal powering technique -the wavefront could be corrected within the entire clear aperture of the lens. Modified lens meets low aberration requirements for ophthalmic applications (for example,intraocular implant). Finally, a new design of a wide aperture tunable modal control Fresnel lens was investigated. Imaging performance of the proposed Fresnel lens was evaluated and compared with the reference lens built using traditional modal control approach. The prototype device demonstrated the increase of optical powerin comparison with a conventional modal control lens of the same aperture size. A theoretical model and numerical simulations of the Fresnel lens design were presented. Simulations demonstrated a possibility of noticeable image quality improvement obtained using optimized voltages and frequencies.

APA, Harvard, Vancouver, ISO, and other styles

9

Haddock, Joshua Naaman. "Liquid Crystal Based Electro-Optic Diffractive Spectacle Lenses and Low Operating Voltage Nematic Liquid Crystals." Diss., Tucson, Arizona : University of Arizona, 2005. http://etd.library.arizona.edu/etd/GetFileServlet?file=file:///data1/pdf/etd/azu%5Fetd%5F1304%5F1%5Fm.pdf&type=application/pdf.

Full text

APA, Harvard, Vancouver, ISO, and other styles

10

Paris, Fabio <1982&gt. "Liquid crystal polymers: macromolecular design for enhanced performances." Doctoral thesis, Alma Mater Studiorum - Università di Bologna, 2010. http://amsdottorato.unibo.it/2466/.

Full text

Abstract:

During this work, done mainly in the laboratories of the department of Industrial Chemistry and Materials of the University of Bologna but also in the laboratories of the Carnegie Mellon University in collaboration with prof. K. Matyjaszewski and at the university of Zaragoza in collaboration with prof. J. Barberá, was focused mainly on the synthesis and characterization of new functional polymeric materials. In the past years our group gained a deep knowledge about the photomodulation of azobenzene containing polymers. The aim of this thesis is to push forward the performances of these materials by the synthesis of well defined materials, in which, by a precise control over the macromolecular structures, better or even new functionality can be delivered to the synthesized material. For this purpose, besides the rich photochemistry of azoaromatic polymers that brings to the application, the control offered from the recent techniques of controlled radical polymerization, ATRP over all, gives an enormous range of opportunity for the developing of a new generation of functional materials whose properties are determinate not only by the chemical nature of the functional center (e.g. azoaromatic chromophore) but are tuned and even amplified by a synergy with the whole macromolecular structure. Old materials in new structures. In this contest the work of this thesis was focused mainly on the synthesis and characterization of well defined azoaromatic polymers in order to establish, for the first time, precise structure-properties correlation. In fact a series of well defined different azopolymers, chiral and achiral, with different molecular weight and highly monodisperse were synthesized and their properties were studied, in terms of photoexpansion and photomodulation of chirality. We were then able to study the influence of the macromolecular structure in terms of molecular weight and ramification on the studied properties. The huge amount of possibility offered by the tailoring of the macromolecular structure were exploited for the synthesis of new cholesteric photochromic polymers that can be used as a smart label for the certification of the thermal history of any thermosensitive product. Finally the ATRP synthesis allowed us to synthesize a total new class of material, named molecular brushes: a flat surface covered with an ultra thin layer of polymeric chain covalently bond onto the surface from one end. This new class of materials is of extreme interest as they offer the possibility to tune and manage the interaction of the surface with the environment. In this contest we synthesized both azoaromatic surfaces, growing directly the polymer from the surface, and mixed brushes: surfaces covered with incompatible macromolecules. Both type of surfaces acts as “smart” surfaces: the first it is able to move the orientation of a LC cell by simply photomodulation and, thanks to the robustness of the covalent bond, can be used as a command surface overcoming all the limitation due to the dewetting of the active layer. The second type of surface, functionalized by a grafting-to method, can self assemble the topmost layer responding to changed environmental conditions, exposing different functionality according to different environment.

APA, Harvard, Vancouver, ISO, and other styles

11

Márquez, Ruiz Andrés. "Accurate predictive model for twisted neumatic liquid crystal devices. Application for generating programmable apodizers and Fresnel lenses." Doctoral thesis, Universitat Autònoma de Barcelona, 2001. http://hdl.handle.net/10803/3331.

Full text

APA, Harvard, Vancouver, ISO, and other styles

12

Nair, Bindu R. 1974. "Design, synthesis and characterization of side chain liquid crystal segmented polyurethanes." Thesis, Massachusetts Institute of Technology, 2000. http://hdl.handle.net/1721.1/9030.

Full text

Abstract:

Thesis (Ph.D.)--Massachusetts Institute of Technology, Dept. of Materials Science and Engineering, 2000.
Includes bibliographical references.
Side chain liquid crystal polyurethanes are liquid crystal elastomers with the potential to couple mechanical stress fields with optical changes brought on by liquid crystal alignment. These materials excite interest because they are the first thermoplastic liquid crystal elastomers (LCTPEs) that utilize the physics of microphase segregation rather than chemical crosslinking to achieve elastomeric properties: LCTPEs offer the potential to use traditional plastic processing technologies to effect the liquid crystal monodomain ordering required for mechanooptic applications. This thesis describes the design. synthesis and characterization of two series of side chain liquid crystal po I yurethanes. The first series of polyurethanes are made with traditional hard segments and cyano-biphenyl mesogens pendant on the soft segment. The synthesis of the soft segment macrodiol. a carbinol endcapped hydromethylsiloxane oligomer that can be functionalized with mesogen via a hydrosilylation technique, is effected by a polycondensation approach. These side chain liquid crystalline (LC) siloxane macromonomers are then converted to segmented polyurethanes using traditional urethane chemistry. Structural analysis and characterization of the resulting polymers is provided. along with a comparison study of the thermal and optical behavior of these urethanes as the spacer length is increased from 3 to 8 methylene units. Discussions of the effects of the hard segment mobility on the phase behavior of these LC polyurethanes is offered. Fourier-transform infrared (FT-IR) dichroism experiments performed on the cyano-biphenyl polyurethanes provide an opportunity to study the interplay between polyurethane morphology and liquid crystal ordering as the material is exposed to mechanical deformation. This complex material follows the trend established in the literature for both side chain liquid crystal siloxane homopolymers and segmented polyurethanes. At low strains. the soft segments align with the strain inducing an orientation in the "lone" horn segments. Up to strains of 40%, the LC mesogens align with the strain field and the hard segments in hydrogen bonded domains align perpendicular to the field. At strains above 40%, a rearrangement of the ordering that results in symmetric layers and hard segments aligning parallel to the field is found. A model is proposed to represent these findings. and reflections on the cooperative movement of the different macromolecular components of the polyurethane are offered. Phase modulated dynamic Ff-IR experiments are performed to study the response of these materials to sinusoidal mechanical perturbations in an attempt to further understand the response of the polyurethanes to mechanical fields. In dynamic Ff-IR. the viscoelastic reorientation of various segments of the macromolecule can be monitored as a function of applied strain. Evidence is presented for the two types of hard segments: those involved in hydrogen bonding within hard domains, and those found in "lone" hard segments in the soft matrix. Evidence is also presented for two types of mesogens: those found in smectic layers. and those not involved in smectic ordering postulated to be located at the hard domain interface. The hard domains and the smectic layers have strong viscous components to their mechanical response. The "free" mesogens and the "lone" hard segments, on the other hand, exhibit a more elastic response. Once again. evidence for the mechanical coupling of the hard segments and the LC mesogens is of~·ered. In an attempt to improve the mechanical properties of the LC segmented polyurethanes. and to explore piezoelectric and electro-mechanical behaviors. new LC segmented polyurethanes are designed with higher overall molecular weight. longer soft segments. higher degrees of microphase segregation. and smectic C* mesogens. Vinylmethylsiloxane macrodiols are anionically synthesized using a diifunctional intitiator. and then polymerized to form segmented polyurethanes by condensation reactions with diisocyanates and chain extenders. The degree of functionalization of the soft segment. and the length of the hard segment are varied in attempts to decrease the degree of mechanical coupling between the hard segment and the mesogens. It is found that polyurethanes with 50% functionalized soft segments provide phase segregated morphologies. form cohesive polyurethane films. and show decoupling in the thermal phase behavior of the LC soft segment and the hard segment. The study of side chain liquid crystal polyurethanes described in this thesis provides a fundamental understanding of the properties of this new class of materials. The interdependance of the hard segment and the mesogen on the thermal and mechanical responses of these materials is a key finding. The development of LC polyurethanes in which this cooperative interaction is muted leads to materials with great potential for mechano-optic applications. The findings reported here should be helpful in testing the piezoelectric and mechano-responsive behaviors of these promising materials.
by Bindu R. Nair.
Ph.D.

APA, Harvard, Vancouver, ISO, and other styles

13

Georgiou, Andreas. "Design of spot generating holograms for reconfigurable liquid crystal optical interconnects." Thesis, University of Cambridge, 2006. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.614147.

Full text

APA, Harvard, Vancouver, ISO, and other styles

14

Semyonov, Alexander N. "Design, Synthesis and Characterization of Fluorescent Dyes and Liquid Crystal Semiconductors." Kent State University / OhioLINK, 2006. http://rave.ohiolink.edu/etdc/view?acc_num=kent1153556141.

Full text

APA, Harvard, Vancouver, ISO, and other styles

15

Imrie, C. T. "Molecular flexibility in the design of low molar mass liquid crystals." Thesis, University of Southampton, 1988. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.233014.

Full text

APA, Harvard, Vancouver, ISO, and other styles

16

Huang, Hanyang. "Adaptive Elastomer-liquid Lenses for Advancing the Imaging Capability of Miniaturized Optical Systems." The Ohio State University, 2019. http://rave.ohiolink.edu/etdc/view?acc_num=osu1562076808810062.

Full text

APA, Harvard, Vancouver, ISO, and other styles

17

Murigi, Francis. "DESIGN, SYNTHESIS, AND CHARACTERIZATION OF INDANE 2,5-DIKETOPIPERAZINES FOR LIQUID CRYSTAL APPLICATIONS." Diss., The University of Arizona, 2011. http://hdl.handle.net/10150/202756.

Full text

Abstract:

Non-covalent interactions are of great importance in biology, chemistry, and material sciences. Although much information about different types of non-covalent interactions is available, incorporating them in a molecular design to generate a molecule that can undergo association to form a molecular assembly with bulk properties of interest is a challenge. To understand and harness intermolecular interactions, we have designed an indane 2,5-diketopiperazine (DKP) scaffold. Crystal engineering studies with this scaffold show that the molecules assemble into one dimensional tapes via reciprocal amide hydrogen bonds, tapes assemble into two dimensional sheets via arene-arene interactions, and sheets assemble into three dimensional solids via van der Waals contacts. A series of tetraalkoxy-substituted DKPs previously investigated exhibited liquid crystalline behavior. A new class of DKPs with one alkoxy substituent, rather than two, on each benzene ring has been synthesized. Thermochemical studies of the new DKPs by differential scanning calorimetry and polarized optical microscopy show that they are not liquid crystalline as expected. However, in the process of making the DKPs, conformationally constrained tyrosine analogues, (R)- and (S)-5-hydroxy-2-aminoindan- 2-carboxylic acids, were prepared by chromatographic separation of diastereomeric dipeptide derivatives formed from N-Boc-L-phenylalanine. Absolute configurations were assigned by X-ray crystallographic analysis. The series of tetraalkoxy-substituted DKPs showed a remarkable trend in freezing point. The freezing point for the series decreases with an increase in alkyl chain length. To understand the relationship between the crystal packing interactions and the freezing point trend, a study of the association of DKPs in solution by NMR was initiated. An Nmethylated 2,5-diketopiperazine was previously synthesized and studied by NMR using chloroform as solvent to obtain equilibrium constants for self association. Attempted multi-step syntheses of a more lipophilic N-3,7-dimethyloctyl 2,5-diketopiperazine, which was expected to have solubility in non-interfering solvents such as carbon disulfide, benzene, and carbon tetrachloride, failed. In response, a direct and concise method for accessing N-alkyl DKPs was developed, and an N-decyl 2,5-diketopiperazine was synthesized. X-ray crystallographic analysis of the N-decyl 2,5-diketopiperazine reveals formation of dimers via hydrogen bonding in the solid state.

APA, Harvard, Vancouver, ISO, and other styles

18

Yoo, Hyun Seung. "Color Illusions on Liquid Crystal Displays and Design Guidelines for Information Visualization." Thesis, Virginia Tech, 2007. http://hdl.handle.net/10919/36372.

Full text

Abstract:

The influence of color on size and depth perception has been explored for a century, but there is very limited research on interventions that can reduce the color illusions. This study was motivated to identify interventions and propose design guidelines for information visualization, especially where size judgment is critical.

This study replicated the color size illusion and color depth illusion on an LCD monitor and it was found that yellow is the smallest and farthest color among red, yellow, green, and blue on a white background. Three types of interventions (background brightness, border color, and background grid brightness) were tested to identify the conditions that reduce the color illusions, but all of them were not statistically significant.

Based on the experiment results and literature survey, design guidelines were proposed. To extend the guidelines to the bioinformatics field, design recommendations were proposed and implementation examples were illustrated. Evaluations on design implementations were evaluated by interviewing domain experts.

Additionally, the relationship between the color size illusion and the color depth illusion was explored.

Master of Science

APA, Harvard, Vancouver, ISO, and other styles

19

Burns, Dwayne C. "Design and characterisation of a ferroelectric liquid crystal over silicon spatial light modulator." Thesis, University of Edinburgh, 1995. http://hdl.handle.net/1842/1541.

Full text

Abstract:

Many optical processing systems rely critically on the availability of high performance, electrically-addressed spatial light modulators. Ferroelectric liquid crystal over silicon is an attractive spatial light modulator technology because it combines two well matched technologies. Ferroelectric liquid crystal modulating materials exhibit fast switching times with low operating voltages, while very large scale silicon integrated circuits offer high-frequency, low power operation, and versatile functionality. This thesis describes the design and characterisation of the SBS256 - a general purpose 256 x 256 pixel ferroelectric liquid crystal over silicon spatial light modulator that incorporates a static-RAM latch and an exclusive-OR gate at each pixel. The static-RAM latch provides robust data storage under high read-beam intensities, while the exclusive-OR gate permits the liquid crystal layer to be fully and efficiently charge balanced. The SBS256 spatial light modulator operates in a binary mode. However, many applications, including helmet-mounted displays and optoelectronic implementations of artificial neural networks, require devices with some level of grey-scale capability. The 2 kHz frame rate of the device, permits temporal multiplexing to be used as a means of generating discrete grey-scale in real-time. A second integrated circuit design is also presented. This prototype neuraldetector backplane consists of a 4 x 4 array of optical-in, electronic-out processing units. These can sample the temporally multiplexed grey-scale generated by the SBS256. The neurons implement the post-synaptic summing and thresholding function, and can respond to both positive and negative activations - a requirement of many artificial neural network models.

APA, Harvard, Vancouver, ISO, and other styles

20

Ichim, Ionut Cameliu. "Novel chiral liquid crystal organic-inorganic hybrid nanoparticle systems : design, synthesis and investigation." Thesis, University of Hull, 2013. http://hydra.hull.ac.uk/resources/hull:7241.

Full text

Abstract:

A first step is taken towards the validation of organic synthesis techniques. Small molecular organic compounds were prepared as intermediates for the liquid crystal materials which exhibit room temperature cholesteric mesophases. These cholesterol based materials were then attached to silsesquioxanes. Both materials have low melting points and low transition temperatures. Phase diagrams, contact and miscibility experiments were performed in order to explain a more complicated cholesteric phase behaviour. The cholesteric mesogens were chemically attached to gold and iron/platinum nanoparticles. For all end materials exhaustive characterisation methods were applied. The questions that were tried to be answered were related to the attachment of cholesterol based mesogens to silsesquioxane cores. Furthermore, the organic-silicon hybrid systems were used as a model for the mesogen covered gold and iron/platinum nanoparticles. Cholesterol based liquid crystals with chiral nematic mesophase at room temperature were obtained. Hybrid systems with very short pitch cholesteric phase and low transition temperatures were also prepared. A new method for preparing gold nanoparticles was implemented. The present results indicate that it is possible to prepare nanoparticles with chiral nematic phase behaviour close to room temperature and iron/platinum nanoparticles with liquid crystal groups attached.

APA, Harvard, Vancouver, ISO, and other styles

21

Thompson, Dane C. "Characterization and Design of Liquid Crystal Polymer (LCP) Based Multilayer RF Components and Packages." Diss., Georgia Institute of Technology, 2006. http://hdl.handle.net/1853/10498.

Full text

Abstract:

This thesis discusses the investigation and utilization of a new promising thin-film material, liquid crystal polymer (LCP), for microwave and millimeter-wave (mm-wave [>30 GHz]) components and packages. The contribution of this research is in the determination of LCP's electrical and mechanical properties as they pertain to use in radio frequency (RF) systems up to mm-wave frequencies, and in evaluating LCP as a low-cost substrate and packaging material alternative to the hermetic materials traditionally desired for microwave circuits at frequencies above a few gigahertz (GHz). A study of LCP's mm-wave material properties was performed. Resonant circuit structures were designed to find the dielectric constant and loss tangent from 2-110 GHz under both ambient and elevated temperature conditions. Several unique processes were developed for the realization of novel multilayer LCP-based RF circuits. These processes include thermocompression bonding with tight temperature control (within a few degrees Celsius), precise multilayer alignment and patterning, and LCP laser processing with three different types of lasers. A proof-of-concept design that resulted from this research was a dual-frequency dual-polarization antenna array operating at 14 and 35 GHz. Device characterization such as mechanical flexibility testing of antennas and seal testing of packages were also performed. A low-loss interconnect was developed for laser-machined system-level thin-film LCP packages. These packages were designed for and measured with both RF micro-electromechanical (MEM) switches and monolithic microwave integrated circuits (MMICs). These research findings have shown LCP to be a material with uniquely attractive properties/capabilities for vertically integrated, compact multilayer LCP circuits and modules.

APA, Harvard, Vancouver, ISO, and other styles

22

Khan, Jahanzeb. "Design of Microstrip Patch Antenna on Liquid Crystal Polymer (LCP) for Applications at 70GHz." Thesis, University of Gävle, Department of Technology and Built Environment, 2008. http://urn.kb.se/resolve?urn=urn:nbn:se:hig:diva-807.

Full text

Abstract:

The demand of small size electronic systems has been increasing for several decades. The physical size of systems is reduced due to advancements in integrated circuits. With reduction in size of electronic systems, there is also an increasing demand of small and low cost antennas. Patch antennas are one of the most attractive antennas for integrated RF front end systems due to their compatibility with microwave integrated circuits. To fulfil the demand of integrated RF front end systems, a design of microstrip patch antenna with optimum performance at 70GHz is investigated. The procedure could be extended to design other planar antennas that act in a similar way.

In this work, three different design methods to design patch antennas for applications at 70GHz are investigated that include use of analytical models, numerical optimization, and numerical variation of dimensions. Analytical models provide a basic understanding of the operation of a patch antenna and they also provide approximate dimensions of a patch antenna for a targeted frequency without using numerical simulations. However, as the operating frequencies of RF systems reach mm-wave frequencies, we expect that the accuracy of analytical models become less accurate. For example, the excitation of substrate modes and effect of ground size are not predicted in simple analytical models.

Due to these expected limitations of the analytical design methods, the accuracy of these models is investigated by numerical electromagnetic field simulations. In this work, CST Microwave Studio Transient Solver is used for that purpose. In order to make sure that the appropriate settings of the solver are applied, the simulation settings such as mesh density, boundary conditions and the port dimensions are investigated. The simulation settings may affect computation time and convergence of the results. Here, in this work, the accuracy of the simulator for a specific design of inset feed rectangular patch antenna is verified. The patch dimensions obtained from analytical calculations are optimized at 70GHz by using the optimizer of the transient solver. The patch dimensions obtained from optimizer are verified by varying the patch dimensions in equidistant steps around the found result of the optimizer.

In a rectangular microstrip patch antenna design, the use of a width of 1.5 times the length is an approximate rule of thumb [1] for low dielectric constant substrates. It is also investigated how the performance properties of a microstrip patch antenna are affected by varying the width to length ratio of the patch. There are occasions where a different ratio is required because of space limitations, or to change the input impedance. The patch designs having various width to length ratios were optimized with the feed location.

The analytically calculated dimensions provided good initial values of the rectangular patch antenna for further optimization using more accurate techniques. The design have been optimized at 70GHz for the investigated mesh density, boundary conditions and the port dimensions. The numerical variation of dimensions is found to be most reliable among the investigated design methods but it is more complicated with many parameters.

APA, Harvard, Vancouver, ISO, and other styles

23

Kamberaj, Hiqmet. "Simulation and modelling of liquid crystal mesophases linked to the design of real materials." Thesis, Manchester Metropolitan University, 2005. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.411705.

Full text

APA, Harvard, Vancouver, ISO, and other styles

24

Cos, Córcoles Joaquín. "Design and modelling of photonic crystals with anisotropic components." Doctoral thesis, Universitat Rovira i Virgili, 2010. http://hdl.handle.net/10803/8479.

Full text

Abstract:

La actual era de las comunicaciones requieren dispositivos para el tratamiento de la información cada vez más eficientes en términos de velocidad, consumo y tamaño. Los dispositivos basados en cristales fotónicos con componentes anisotrópicos pueden aplicarse para el diseño de dispositivos electro-ópticos con características convenientes tales como la sintonizabilidad. En este trabajo se han analizado y diseñado varios dispositivos unidimensionales (1D), bidimensionales (2D) y tridimensionales (3D) sintonizables basados en cristales fotónicos de silicio y cristal líquido. En el caso de los cristales fotónicos 1D se ha propuesto dos ecualizadores ópticos basados en interferómetros
Fabry-Pèrot. Estos dispositivos permiten sintonizar 2 resonancias en sus frecuencias y amplitudes de transmisión. En cuanto a los cristales fotónicos 2D, se ha analizado filtros y guías de onda sintonizables, proponiendo en ambos casos aplicaciones como interruptores ópticos. Por último, se ha desarrollado una aproximación para el análisis de cristales fotónicos 3D. Mediante dicha aproximación se ha explicado la presencia de máximos en reflexión en altas frecuencias así como se han analizado 3 muestras experimentales.
The present Communications Age requires more and more efficient devices in terms of speed, consumption and size for the treatment of information. Nanoscale photonic crystal devices and anisotropic materials is expected to provide a possibility to create electro-optical devices with required characteristics such us tunability. In this work we have analyzed and designed several tunable one-dimensional (1D), two-dimensional (2D) and three-dimensional (3D) devices based on silicon photonic crystals and liquid crystal. In the case of 1D photonic crystals, two optical equalizers based on Fabry-Perot interferometers have been proposed. These devices allow tuning 2 resonances in frequencies and transmission amplitudes. As for 2D photonic crystals, tunable filters and waveguides have been analyzed, offering both applications as optical switches. Finally, we have developed an approach for the analysis of 3D photonic crystals. The presence of reflection peaks in high frequencies has been explained by this approach and 3 experimental samples were analyzed.

APA, Harvard, Vancouver, ISO, and other styles

25

Wells, Kirk Edward. "Crystal engineering: Design, syntheses and characterization of a family of compounds demonstrating liquid crystalline properties." Diss., The University of Arizona, 2001. http://hdl.handle.net/10150/279831.

Full text

Abstract:

Intermolecular interactions govern molecular self-recognition and self-assembly, giving rise to 3-dimensional solids. Thus, independent intermolecular interactions should result in a predictable crystal packing. Our working hypothesis is the crystal packing of symmetrically substituted tetra-n-alkoxy-bis-indane-piperazinediones of H-shaped topography will be governed by three factors: First, assembly of molecules into "one-dimensional" tapes through establishment of reciprocal amide hydrogen bonds. Second, assembly of the tapes into "two-dimensional" grooved sheets through establishment of edge-to-face arene interactions. Third, assembly of the sheets into "three-dimensional" solids by "tongue-in-groove" interdigitation of the n-alkyl "tails" in extended conformations independent of chain length. Liquid crystal properties are anticipated for molecules with hydrocarbon chains of sufficient length. Rupture of one or more of the three structure-determining interactions may be independent of the others and observable. "Dissection" of the melting process by correlation of crystallographic data with thermochemical data would permit formulation of a mechanism for melting. Compounds of this homologous series with methoxy, ethoxy, butoxy, hexyloxy, octyloxy and nonyloxy substituents have been synthesized, crystallized, and studied by X-ray crystallography, differential scanning calorimetry (DSC) and optical microscopy. The solid-state structures for the first three in the series were determined and each engaged in intermolecular amide-to-amide hydrogen bonding interactions that established "ladder-like" parallel tapes. Intertape organization was governed by the development of arene and/or van der Waals contact interactions. The melting behaviors of the series were remarkable in that these were not only high melting solids but most also demonstrate transitions by DSC at lower temperatures and magnitude consistent with liquid crystalline behavior. Also remarkable and consistent with liquid crystalline behavior are the optical properties of the longer alkoxy substituted compounds of the series, demonstrating birefringence of cross-polarized fight. In the case of the tetra-n-hexyloxy compound a transition was observed by optical microscopy that correlates with DSC data. Design, syntheses and characterizations of this new family of compounds, which are highly ordered at the molecular level, supporting our hypothesis of liquid crystalline behavior, are discussed. Using these data a mechanism of melting is postulated and discussed.

APA, Harvard, Vancouver, ISO, and other styles

26

Komarčević, Miloš. "Design and optimisation of nematic liquid crystal on silicon diffractive structures for beam steering applications." Thesis, University of Cambridge, 2006. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.613736.

Full text

APA, Harvard, Vancouver, ISO, and other styles

27

Hess, Allison Elizabeth. "DESIGN AND FABRICATION OF POLYNORBORNENE- AND LIQUID CRYSTAL POLYMER-BASED ELECTRODE ARRAYS FOR BIOMEDICAL APPLICATIONS." Case Western Reserve University School of Graduate Studies / OhioLINK, 2008. http://rave.ohiolink.edu/etdc/view?acc_num=case1207335588.

Full text

APA, Harvard, Vancouver, ISO, and other styles

28

Qian, Shilong. "The design and fabrication of miniature microwave bandpass filters using multilayer liquid crystal polymer technology." Thesis, Heriot-Watt University, 2014. http://hdl.handle.net/10399/2955.

Full text

Abstract:

This thesis presents the design and fabrication techniques for miniature microwave bandpass filters using multilayer liquid crystal polymer (LCP) technology. As a multilayer technology for microwave devices, LCP is of low cost and light weight. It also has excellent electrical properties across a wide frequency range. These characteristics make it promising for the development of next generation microwave devices for applications across commercial, defence and civil sectors. However, very limited work has been found in the open literature to apply this technology to the design of miniature bandpass filters, especially at low microwave frequencies. In addition, the reported work shows lack of fabrication techniques, which limits the size reduction of multilayer LCP devices. To address these problems, this thesis develops advanced fabrication techniques for sophisticated LCP structures, such as multilayer capacitors, via connections and cavities. These techniques are then used to support the design of novel miniature bandpass filters for wideband and narrowband applications. For the design of miniature wideband bandpass filters, a cascaded approach, which combines highpass and lowpass filters, is presented first to provide a flexible design solution. This is followed by another novel ultra-wideband bandpass filter which produces extra transmission zeroes with minimum number of elements. It does not only have high performance but also a compact structure for high yield fabrication. For narrowband applications, two types of advanced coupled-resonator filters are developed. One type produces a very good selectivity at the upper passband edge, and its spurious-free stopband is extremely wide and of high interference attenuation. The other type, based on novel mixed-couplings approaches developed in this thesis, provides a solution to produce almost the same response as the coupling matrix prototype. This type is used to generate arbitrarily-located transmission zeroes. All designs presented in this thesis are simulated using CAD design tools and then validated by measurements of fabricated samples. Good agreements between simulations and measurements are shown in the thesis.

APA, Harvard, Vancouver, ISO, and other styles

29

Kao, Yung-Yuan, and 高永原. "Design and Fabrication of Multiple Electrodes in Varied Liquid Crystal Lenses Functioning Convergence, Divergence and 3D Display." Thesis, 2012. http://ndltd.ncl.edu.tw/handle/24699299033614805160.

Full text

Abstract:

博士
國立交通大學
電控工程研究所
100
This dissertation is dedicated to study and discuss applications of liquid crystal (LC) lenses with designed multiple electrodes, which consists of two main parts -- imaging optics system and 3D display system. For the application to imaging optics system, novel convergent/divergent LC lens devices with large aperture and multiple ring electrodes in unequal widths are proposed by this work, in order to offer tenability on focusing quality and to render a better refraction index distribution for focusing, as compared to the past hole-type LC lenses. A new fabrication process in the wafer level to bury bus lines is developed for generation smooth electrical fields over the lens aperture. In addition, a new LC lens using dual-frequency liquid crystals (DFLC) is proposed to improve the recovery time with a ring-and-pie electrode pattern through a suitable driving scheme. For this device, one can control the orientation of liquid crystal directors via a three-stage switching procedure on the particularly-designed ring-and-pie electrode pattern. This aims to eliminate the disclination lines, and using different drive frequencies to reduce the recovery time. For the application to 3D display system, a liquid crystal lenticular lens (LCL-lens) array device which is proposed to compose an auto-stereoscopic display, in order to replace conventional lenticular lens sheet. This study proposes design criteria of LCL-lens array for auto-stereoscopic display system. An optical model is built with LCL-lens array to analyse and qualify its crosstalk and performance, while an observer observes the system in different observer distances and angles. In addition, two LCL-lens array devices are designed with interlaced and multi- electrode pattern to realize 2.8 and 4.4 inch fabrications respectively, and then be measured to result their performances in this dissertation.

APA, Harvard, Vancouver, ISO, and other styles

30

簡偉哲. "Reduction of Disclination Lines in Liquid Crystal Lenses." Thesis, 2012. http://ndltd.ncl.edu.tw/handle/82487153903478570633.

Full text

Abstract:

碩士
國立彰化師範大學
光電科技研究所
100
The effect of pretilt angle on disclination lines of the liquid crystal (LC) lens is investigated. When the pretilt angle of LCs is about 10∘,the disclination lines move to the margin of the LC lens. As the pretilt angle of LCs is higher than 20∘, the disclination lines of the LC lens may be removed. We also investigate the effect of LC lens arrays on the aberration correction of an optical system. The obtained result shows that the correction of aberration is evident when the etched electrode hole-pattern is close packed.

APA, Harvard, Vancouver, ISO, and other styles

31

Lin, Hung-Chun, and 林弘峻. "Electrically tunable focusing liquid crystal lenses and applications." Thesis, 2012. http://ndltd.ncl.edu.tw/handle/60599425848446453289.

Full text

Abstract:

博士
國立交通大學
光電工程學系
101
Electrically tunable focusing liquid crystal lenses were first proposed in 1979. However, the slow response time, small tunable focal range and high driving voltage of the LC lens impede applications. In this dissertation, we started from a study of optics and physics of the LC lens and discussed the design guideline of the LC lens. In the conventional operation of a positive LC lens only in the imaging system, the large tunable focal range of the LC lens requires the large thickness of the LC layer (or cell gap), but in this way the response time is slow (~30 sec) and the light scattering is strong. To obtain fast response time(<1 sec) and large tunable range (350 cm to 10 cm), we demonstrated a image system using two mode switching which is based on the phase change between the positive and the negative LC lens. Moreover, in order to reduce the driving voltage of the conventional LC lens with hole-patterned electrode and obtain a LC lens with a short focal length which is required in most of image system and is also difficult to realize with a homogeneous cell gap, we designed a LC lens with low driving voltage and short focal length by adopting the built-in polymeric layer. By controlling the spatial distribution of the refractive indices and the spatial distribution of the dielectric constants of the built-in polymeric layer, the polymeric layer can not only be a built-in lens with fixed focal length but also adjust the voltage distribution across the LC layer and align LC directors. As a result, the focal length of the LC lens could be shifted to be short; meanwhile, the driving voltage can be reduced by the polymeric layer. Besides the image system, we also demonstrated the electrically tunable focusing pico projectors with the conventional LC lens and the LC lens adopting the polymeric layer. Ultimately, a holographic projector with optical zooming function by using a LC lens is also demonstrated. The LC lens can be used to solve the color breakup in holographic projectors. In this dissertation, we have overcame several main problems of the LC lens, such as response time, tunable range and the driving voltage, and we also demonstrated various applications based on the LC lenses. We believe this dissertation can open a new window in optical designs based on the classic geometrical optics and also inspire new applications in endoscopes, image stabilization systems, night vision systems, solar cells and eyeglasses.

APA, Harvard, Vancouver, ISO, and other styles

32

Yen, Shih-Chiang, and 顏仕強. "Studies of Multistable Variable-Focus Liquid Crystal Lenses." Thesis, 2013. http://ndltd.ncl.edu.tw/handle/peprsy.

Full text

Abstract:

碩士
國立虎尾科技大學
光電與材料科技研究所
101
In this study, a multistable tunable-focus lens based on liquid crystal doped self-assembly material (12-hydroxystearic acid; HSA) with hole-patterned electrode method is demonstrated. The mechanism of multi-stable characteristic is that hydrogen-bond forces between HSA molecules make the HSA-doped LC material to form a gel compound in room temperature. Firstly, we control the temperature of sample to 100 oC. Secondly, apply a voltage to the sample in the high temperature, and then to cool the sample to room temperature in an applied external electric field. Finally, turn off the applied voltage. After the experimental process, various focal length of lens can be stabilized, which can be used to save power. The experimental results show that the tunable range of focal length is 1.6 ~ 5 cm when a voltage (V =20 ~ 80 V) is applied in the process. The result is similar to that of a lens based on pure LCs. Besides, a LC lens coated with Au-PVA films on the outer surface of substrates, which are used as heating films, is fabricated. The results indicate that the focal length can be tuned after simutaneous the irradiation of laser light and the application of a voltage. The tunable range is the same to that with the heating method. The optically and electrically controlled LC lens with multistable characteristic has potential for practical application.

APA, Harvard, Vancouver, ISO, and other styles

33

Liao, Lin-Yao, and 廖凌嶢. "Liquid Crystal Lenses for Imaging Application in Mobile Devices." Thesis, 2011. http://ndltd.ncl.edu.tw/handle/84104237181028861250.

Full text

Abstract:

博士
國立交通大學
光電工程學系
99
Mobile devices become necessary products for daily life’s use in recent years. When perform functions of photography, phantom identification, computer vision, and image communications, lens-heads play an important role to deal with the basic function of imaging. Liquid crystal (LC) lens has unique properties such as electrically tunable focal length. Since there are no moving mechanical parts, LC lens is smaller and lighter than conventional tunable glass lenses. In mobile devices, LC lens can directly combine with mobile lens-module in front of the lens-head, and easily perform auto-focusing (AF) function by driving appropriate voltage to focus objects at different distances. However, inferior optical quality, slow focusing time, and high driving voltage are current major issues of LC lenses’ study. These drawbacks make LC lenses unpractical and unfeasible in real usage for mobile devices. In this thesis, we first started from Multi-electrode Driven LC lens (MeDLC lens) to precisely control profiles of LC lens for different focal length. By the multi-electrode, we demonstrate highly controlled freedom for modifying the index distributions for each focal length to obtain similar and superior focusing profiles. In the second part, Gradient-driven LC lens (GDLC lens) was proposed to intrinsically improve the driving efficiency. We utilized a resistance layer connected with electrodes as the control layer. The benefit of this structure is that the applied electric field can be efficiently employed and a gradient distribution in voltage can be produced. By GD-LC lens, the driving voltage typically higher than tens root-mean-square voltages was reduced down to less than 5Vrms for imaging 6cm closed objects. In the third part, Over-drive (OD) method for LC lenses was proposed to investigate focusing behavior. A switching operation in this method according to the focusing profile was used to reduce the focusing time. Performing with GDLC lens, we yielded 600msec focusing time by a LC lens with 60um cell gap and 2mm aperture size for capturing the 6cm objects. By combining these results, we not only dramatically improved the performance for current LC lenses but also to break through the issues of the current studies. Our outcome, furthermore, make the use of LC lenses for commercial mobile devices more feasible and practical.

APA, Harvard, Vancouver, ISO, and other styles

34

Yang, Ren-Kai, and 楊仁凱. "Optical Characteristics of Liquid Crystal Lenses with Spherical Electrodes." Thesis, 2018. http://ndltd.ncl.edu.tw/handle/26v83m.

Full text

Abstract:

碩士
國立臺灣大學
光電工程學研究所
107
In this thesis, we use liquid crystal simulation software 2dimMOS to investigate the electric potential of liquid crystal lenses with hole-pattern electrode, hole-pattern with additional electrode and spherical electrode. We analyze the electric potential to determine whether the three kinds of liquid crystal lenses with the lens sizes of millimeters can form a continuous electric potential distribution in the liquid crystal layer and the non-uniform electric field could be generated. The refractive index distribution generated by non-uniform electric field in the liquid crystal layer forms a liquid crystal lens. We further investigate whether the hole-pattern electrode with additional electrode liquid crystal lens and the spherical electrode liquid crystal lens have flat potential distribution between the two adjacent lenses and crosstalk occurs consequently. Fabrication of four sizes of liquid crystal lenses range from micrometers to millimeters is also included. Replication process is used and conductive polymer PEDOT:PSS is applied to form spherical electrode. We assemble flattened spherical electrode with ITO glass with PVA to form liquid crystal lens.

APA, Harvard, Vancouver, ISO, and other styles

35

Tsay, Wei-Hung, and 蔡威弘. "A Study of Electrically Tunable-Focusing Liquid Crystal Lenses." Thesis, 2010. http://ndltd.ncl.edu.tw/handle/38941821988423334759.

Full text

Abstract:

碩士
國立交通大學
理學院碩士在職專班應用科技學程
98
We study the electro-optic properties of electrically tunable-focusing liquid crystal (LC) lenses. A spatially inhomogeneous electric field which decreases gradually from the edge to the center makes the gradient-rotation distribution of LC molecules to produce parabolic distribution of refractive indices. The principle of electrically tunable-focusing is that the curvature of the distribution of refractive indices can be changed by applied voltages. In this thesis, we introduce the physical parameters of LC materials and survey literatures of LC lenses. Then, we select a LC lens with hole-patterned electrode to study the focal length, response time, and temperature effect of the LC lens. From the experimental results, we can improve the response time by increasing temperature and the focusing properties remain similiar between the temperature of 20℃ and 60℃.

APA, Harvard, Vancouver, ISO, and other styles

36

Lo, Kuo-Ching, and 羅國卿. "Electrically controllable Fresnel lenses in polymer-liquid crystal composite films." Thesis, 2007. http://ndltd.ncl.edu.tw/handle/17393568344463795460.

Full text

Abstract:

碩士
國立成功大學
光電科學與工程研究所
95
We have demonstrated two types of electrically controllable LC Fresnel lenses based on liquid crystal-polymer composite films in this thesis. First experiment： This experiment elucidates a Fresnel lens using a simple approach that is based on a homogeneously aligned liquid crystal (LC) film with a preformed polymer relief pattern. Experimental results demonstrate that the LC Fresnel lens has polarization-dependent and electrically switchable focusing features. The LC lens has the further advantages of a weak operated field, and high diffraction efficiency. Second experiment： This experiment reports a Fresnel lens in a circularly-symmetric hybrid-aligned liquid crystal (LC) film with a photoconductive polymer layer. An ultraviolet-induced electrode-like pattern of polymer layer under a zone-plate photomask results in alternate unscreened and screened effects of an applied dc-field at conductive and nonconductive regions, respectively. These effects cause a discrepancy of LC reorientation in adjacent zones and in turn generate a Fresnel lens. The focusing of the lens is demonstrated electrically-controllable and polarization-independent. Furthermore, the lens has advantages of an zero-focusing in voltage-off state and a very small operated dc-field range from 0 - 0.3 V/um.

APA, Harvard, Vancouver, ISO, and other styles

37

Chang, Chi-Peng, and 張志鵬. "Studies of liquid crystal Fresnel lenses doped with nano particles." Thesis, 2013. http://ndltd.ncl.edu.tw/handle/77890551103566082335.

Full text

Abstract:

碩士
國立中山大學
物理學系研究所
101
A simple method to make a controllable liquid crystal Fresnel lens with bistable state is proposed based on a surface of polymerization and the characteristic of nanoparticles. The sample is fabricated by a homogeneous aligned substrate and a vertical aligned one of coating polymer film. However, it has low diffraction efficiency. We improve the patterned electrode type with etching electrode structure. Experimental results reveal that liquid crystal Fresnel lens which ITO etching pattern using the nanoparticles doped with liquid crystals has bistable state and high diffraction efficiency.

APA, Harvard, Vancouver, ISO, and other styles

38

Chen, Ming-Syuan, and 陳明璿. "Electrically-tunable optical zoom system by using composite liquid crystal lenses." Thesis, 2011. http://ndltd.ncl.edu.tw/handle/10760061085586789880.

Full text

Abstract:

碩士
國立交通大學
光電工程學系
99
An electrically-tunable optical zoom system using composite liquid crystal (LC) lenses is demonstrated. The main mechanism of electrically tunable focal length of composite LC lenses results from the gradient distribution of refractive indices owning to the orientations of LC directors. In this thesis, we start from analyzing the imaging conditions and the magnification of the optical zoom system. Based on the developed relation between the focusing properties of LC lenses and zoom ratio of the optical zoom system, we developed a composite LC lens consisting of a sub-LC lens and a built-in planar polymeric lens in order to shift negative lens power when the composite LC lens is operated as a negative lens. The electrically-tunable optical zoom system using composite LC lenses has high zoom ratio (~7.9:1), short system length (<10cm) and the object can be zoomed in or zoomed out continuously at the objective distance of infinity to 10 cm. The applications of the optical zoom system using composite LC lenses are also demonstrated in this thesis, such as pico-projectors and webcams.

APA, Harvard, Vancouver, ISO, and other styles

39

Chen, Hung-Shan, and 陳宏山. "Large aperture liquid crystal lenses with tunable lens powers and applications." Thesis, 2016. http://ndltd.ncl.edu.tw/handle/8t3327.

Full text

APA, Harvard, Vancouver, ISO, and other styles

40

Chen, Yu-Chen, and 陳禹辰. "Imaging Applications of spherical Gradient-Driven Liquid-crystal Lenses for Mobile Devices." Thesis, 2011. http://ndltd.ncl.edu.tw/handle/50817660966198973685.

Full text

Abstract:

碩士
國立交通大學
顯示科技研究所
99
In mobile devices, camera has become a basic function today, almost every mobiles has a camera. In photography, optical zoom was eager for consumers nowadays. Optical zoom utilized mechanical movement of lens elements to change the focal length. Since the limit of space, there are no optical zoomable cameras in mobile devices. Liquid Crystal lens is type of electrically-tunable focus lens. However, high operating voltage and slow focusing time are two of the major issues in the liquid crystal lens applications. Spherical Gradient Driven Liquid Crystal Lens (sGD-LC lens) was proposed to solve these two issues. A high-resistance layer was spin-coated above the patterned electrodes, which create a gradient distribution of electric field and preserved majority energy was applied. For a specification with 60?慆 LC cell-gap and 2mm lens aperture, the operating voltage was reduced down to less than 4 volts for 5cm focal length, and the focusing time was dramatically improved to 0.8 seconds. Combining with sGD-LC lens, an auto-focusing system for mobile lens application was realized in this thesis. These features made mobile devices employing LC lens feasible and practical, while LC optical zoom system is also realizable by appropriate optical design.

APA, Harvard, Vancouver, ISO, and other styles

41

Wang, Jhong-yuan, and 王中原. "Studies of polarization-independent liquid-crystal Fresnel lenses with high diffraction efficiency." Thesis, 2009. http://ndltd.ncl.edu.tw/handle/abq9rm.

Full text

Abstract:

碩士
國立中山大學
物理學系研究所
97
This study proposes a polarization-independent liquid-crystal Fresnel lens using twisted nematic liquid crystals (TN-LCs) with two electrodes structure. A photoresist type has high diffraction efficiency, high diffraction efficiency and good polarization independence characteristic. However, its diffraction cannot be completely switched off. A patterned electrode type has the characteristics of the switch-off and good polarization independence. However, it has low diffraction efficiency. We improve the patterned electrode type with two electrodes structure. Experimental results reveal that LC Fresnel lens using the TN-LC with two electrode structures has high diffraction efficiency and a good polarization-independent characteristic.

APA, Harvard, Vancouver, ISO, and other styles

42

Yi-YangChiu and 邱毅揚. "Study of Flexible Fresnel Liquid Crystal Lenses for Fabrication Processes and Optical Performance." Thesis, 2016. http://ndltd.ncl.edu.tw/handle/j47eve.

Full text

Abstract:

碩士
國立成功大學
光電科學與工程學系
104
SUMMARY In this study, a flexible Fresnel liquid crystal lens based on one duplicated PDMS substrate is investigated and demonstrated, which focuses are thermally controllable and polarization independent. When bending angles in the fabricated liquid crystal lens are individually at 0° and 45°, which focuses are corresponded to 3.3 cm and 4.3 cm. When temperature in the lens is at 40°C, LCs shows isotropic phase to achieve a larger focus of 2.8 cm than 2.4 cm at room temperature due to larger value of refractive index. Finally, we confirmed our lens is polarization independent and its focusing efficiency is about 79%, which is closed to our purchased Fresnel lens 85%.

APA, Harvard, Vancouver, ISO, and other styles

43

lin, Fun-Jane, and 林汎貞. "Design and Synthesis of Liquid crystal." Thesis, 1997. http://ndltd.ncl.edu.tw/handle/22549322210806277531.

Full text

Abstract:

碩士
國立中央大學
化學系
85
This thesis describes the synthesis and characterization of various types (series I , II , III and IV) of organic ligand structures and their complexes with different transition metal. For example, series I ; bis[4-(4'-alkoxybenzoxy)phenyl butane-1,3-dione]metal. series II ; bis[N-(3- hydroxypropyl)-4-(4'-alkoxybenzoxy)benzoyl acetone iminato]metal. series III ; {N,N'-ethylene-bis[3,5-di(4'- alkoxybenzoxy)benzoyl acetone iminato}metal and [N,N'-ethylene- bis(3,5-dialkoxy)benzoyl acetone iminato]metal. series IV ; tetraketonebis(1,1'-(1,3-phenylene)-bis [3,3'-(3",4",5"- trialkoxyphenyl)-1,3"-propanedione]metal. By altering the carbon length, the numbers, and the substituted position of the terminal flexible side chains , and /or their complexes with different metal centers, the formation of liquid crystallinity and the mesomorphic properties were characterized and also studied in detail. For the spectroscopic characterization of all compounds, 1H and 13C NMR spectra were used to identify the structure and the purity of the organic compounds, IR spectra was used to confirm the formation the metal complexes by observing the characteristic absorption frequency, and elemental analysis was finally used to confirm the purity. DSC analysis, optical polarised microscopy and XRD diffraction were used to characterize and confirm the structure of the liquid crystalline mesophases. Experimental data indicated that series I , and II , ligands and copper complexes all exhibited smectic phases, however, series III ; ligands and copper complexes exhibited only crystalline phases. Serious IV ﹔Cu, VO, Ni complexes, all exhibited discotic hexagonal disordered phases.

APA, Harvard, Vancouver, ISO, and other styles

44

Ching-YiHuang and 黃靜宜. "Study of patterned electrodes to realize liquid crystal lenses with linearly polarized independent characteristics." Thesis, 2010. http://ndltd.ncl.edu.tw/handle/01301225774467528971.

Full text

Abstract:

碩士
國立成功大學
光電科學與工程研究所
98
In this thesis, we mainly study using patterned electrodes to realize liquid crystal lenses with linearly polarized independent characteristics. The patterned electrodes provide a symmetric non-uniform electrical field, which drives the director orientation of spatial liquid crystals in order that suitable distribution of gradient refractive indices can be achieved in the cells. When an incident light beam passes through the cell, light beam can be converged or divergent according to the conditions of optical path difference generated by refractive index distribution. In this experiment, we use three patterned electrodes to manufacture liquid crystal lenses, including circular hole-pattern liquid crystal lens, point-pattern liquid crystal lens and blu-ray-pattern liquid crystal lens. Observe optical performances of these lenses with distinct liquid crystal and alignment in different voltages, such as interference stripes figure and focal length measurement. Experimental results demonstrate that patterned electrodes to realize liquid crystal lenses with linearly polarized independent characteristics can be achieved by using distinct liquid crystal and alignment.

APA, Harvard, Vancouver, ISO, and other styles

45

Ying-JieWu and 吳盈杰. "Study of Electro-optical Performance of Fresnel Liquid Crystal Lenses Fabricated via Molding Duplication." Thesis, 2015. http://ndltd.ncl.edu.tw/handle/22441099733486322897.

Full text

Abstract:

碩士
國立成功大學
光電科學與工程學系
103
In this thesis, the main investigation is to fabricate electrically switchable phase Fresnel liquid crystal lens (FLCL) by means of molding duplication. The optical performance of the fabricated phase FLCL is mainly measured and investigated including maximum diffraction efficiency, correlation of polarization, and imaging result. The experiment interprets a phase FLCL that which is based on preformed polymer relief structure but uses two different kinds of aligned liquid crystal film, homogeneous alignment (HA) and twisted nematic alignment (TN) individually. Experimental results the phase FLCL with homogeneous alignment has polarization dependent feature, polarization insensitive for 12μm and 18μm cell gap experiment sample with TN alignment, and polarization independent for 24μm cell gap FLCL lens with TN alignment. At present, the high diffraction efficiency is available in this study, 37.15% and 35.28% for HA and TN phase FLCL individually, which is very close to the theoretical maximum value 40.5%. Due to high diffraction efficiency and the refractive index of cured NOA65 (Norland Optical Adhesive 65) is matching to ordinary axis refractive index of nematic liquid crystal E7, the phase FLCL could successfully have not only the same focusing function with traditional convex glass lens, but also could be ON/OFF switch by additional electric field.

APA, Harvard, Vancouver, ISO, and other styles

46

Wang, Sheng-Le, and 王生樂. "Wavelength and focal length tunable reflective Fresnel lenses using liquid crystal spatial light modulators." Thesis, 2018. http://ndltd.ncl.edu.tw/handle/r7gk3z.

Full text

Abstract:

碩士
國立中央大學
光電科學與工程學系
106
We have successfully demonstrated electrically switchable wavelength and focal length tunable reflective Fresnel lenses using liquid crystal spatial light modulators (SLM) based on a liquid crystal on silicon (LCoS) device. The SLM device can display various Fresnel zone plates (FZP) with different grayscales, focal lengths, wavelengths, and others. On the basis of the real time switches of FZP with suitable parameters, the white light focusing based on color sequential and additive color techniques can be realized. First, the corresponding FZPs, plotted by the software of Matlab, for different focal lengths and wavelengths with appropriate ranges of parameters were elucidated. By using such an LCoS device, the phase difference between these two adjacent ring areas of each FZP can be electrically tuned to be about π to approach the maximum focusing efficiency. After analyzing the focusing efficiency of light utilization, the experimentally obtained maximum diffraction efficiencies reached about 36-38%, close to the theoretical limit value of ~40.5%. Second, regarding the FZPs having characteristics of several orders of focal points, we successfully removed the unnecessary rings of FZPs to achieve a new focal point, which was absent in the original FZP. Finally, we also used FZPs to separate the white light, the mixing light of three wavelengths of 632.8 nm, 532 nm, and 450 nm, to the desired color light at their focal points. This experiment proved that the FZP patterns are able to focus the light with the desired wavelength, while others are out of focus or even defocusing. Furthermore, the switching of different FZPs, which correspond to the wavelengths of 632.8 nm, 532 nm, and 450 nm, with its frame time shorter than the limitation of humans’ eyes was adopted to mix these three lights according to the additive color technique. Experimentally, the spectra of focusing lights at their focal points were consistent with the theoretical analyses. The color of the combined lights at the focal points were contributed from the main wavelengths of the incident light source. In other words, we can obtain a white focal point by using various reflective Fresnel lenses.

APA, Harvard, Vancouver, ISO, and other styles

47

LIN, Chih-neng, and 林志能. "Driver Circuit Design for Liquid Crystal Display." Thesis, 2001. http://ndltd.ncl.edu.tw/handle/63305523193565793729.

Full text

Abstract:

碩士
大葉大學
電機工程研究所
89
Liquid crystal display(LCD) have been considered as a viable alternative to CRT due to its potential of achieving light weight, small volume, low voltage, low power. Due to the large number of output buffer in a column driver chip of a flat-panel display., the quiescent current and reliability become very importance. This paper present a low static power, large output swing, and wide operating frequency range class AB output buffer amplifier for driving the large column line capacitance in flat-panel display. A comparator is used in the negative feedback path to eliminate quiescent current in the output stage. With 3.3Vsupply voltage and 700pf load, output swing is from 0.5V to 3V and the operation frequency range is 30KHz to 100KHz. This buffer circuit has been demonstrated successfully using the TSMC’s 0.6 CMOS technology.

APA, Harvard, Vancouver, ISO, and other styles

48

Lin, Jian-Cheng, and 林建成. "Liquid Crystal Display Overdrive Method and Design." Thesis, 2005. http://ndltd.ncl.edu.tw/handle/09898861371106028156.

Full text

Abstract:

碩士
清雲科技大學
電機工程研究所
93
When displaying moving pictures on a TFT-LCD, a blurring, trailing, low dynamic contrast, or color shifts phenomenon may appear on moving pictures. This is caused by slow response time of liquid crystal. An overdrive control method is proposed to improve this deterioration of display quality in moving pictures. By using this method, the liquid crystal response time can be reduced to less then one refresh frame cycle time, especially when the change is between two gray levels. This overdrive controller will be implemented by a FPGA circuit and located in front of timing controller on LCD panel. The relationship between liquid crystal response time and overdrive control method will also be studied.

APA, Harvard, Vancouver, ISO, and other styles

49

Che-JuHsu and 許哲儒. "Using photo-polymerization to improve electro-optical performance and realize polarization-independence in liquid crystal lenses." Thesis, 2013. http://ndltd.ncl.edu.tw/handle/37484884161244610674.

Full text

Abstract:

博士
國立成功大學
光電科學與工程學系
101
The hole-patterned LC lens possesses the advantages of simple fabrication and strong tunable-focus capability. However, because of non-uniform symmetrical electrical fields produced from a circular-hole electrode, the LC molecules in the hole-region easily orient along two opposite directions for homogeneous LC cells, leading to the formation of a disclination line. The disclination line will slow down the response time and lower the image quality. Based on our initial study on the large apertures of LC lenses, disclination lines and zigzag lines typically occur in cells. Unfortunately, zigzag lines and disclination lines will possibly link to each other and permanently stay in the cells to degrade the performance of LC lenses. Therefore, we experimentally study and conclude that suitable rubbing conditions in cells will effectively prevent the problem of linked lines. For convenient operation of the hole-patterned LC lens, we use the method of polymer stabilization to successfully prevent disclination lines in LC lenses. After successfully using the polymer stabilization method to prevent the occurrence of disclination lines, we further increase the concentration of monomers to fabricate coaxially bifocal (CB) LC lenses, and this method is called photo-polymerization. The characteristics of a tunable CB are clearly exhibited when the voltage applied is continuously increased, eventually disappearing until only one focus is left when significantly higher voltages are applied. We simultaneously demonstrate two types of tunable CB LC lenses fabricated via different photocurable processes, and then determine their optical functions. The study in the dissertation is based on LC lenses with a hole-patterned electrode. To effectively exploit the incident light, a dropping-flow alignment method is used to achieve radially symmetric LC distributions in the cell, through which tunable LC lenses can be made as linearly polarization independent. A 7 mm-diameter LC lens is fabricated with a circular hole-patterned electrode; its focal lengths are tunable from infinite to 27.5 cm when voltages from 0 Vrms to 80 Vrms are applied.

APA, Harvard, Vancouver, ISO, and other styles

50

Tsai, Chia-shou, and 蔡家壽. "High-Power Transmissive Liquid Crystal Display Projector Design." Thesis, 2011. http://ndltd.ncl.edu.tw/handle/s8x973.

Full text

Abstract:

碩士
國立臺灣科技大學
電子工程系
99
This thesis proposed high-power transmitted liquid crystal display projector design. The optical simulation software FRED is used to design the projector. The projector system can be divided into light collection system and light projection system. For the light collection system, a reflector is used converge the emitting light of three (in red, green and blue color) high-power light emitted diodes (LEDs). Two types of reflectors are considered. For the square shape reflector, the simulation is based on principles of geometric optics and the simulation results are quite good. However, the power decays tremendously and the pattern is also gradually distorted as the projection distance increases. For the parabolic shape reflector, the LED is located at the focal point of the reflector. Then the reflective light beams would be transmitted in parallel with one another. So, the problem of pattern distortion will be overcome even the distance is increased. The optical beams could be further amended by a polarizer before the red, green and blue LEDs are combined by the X-cube prism, which may either reflect or transmit the coming LED light beams. Finally, the light beams will be converged in to an integral column by the convex lens. 　　For the projection system, the optical simulation software OSLO is used. It is a powerful tool for design optical lens. In the beginning, the OSLO is used to design projection lens of the experimental frame, then all the projection lens’ parameters could be optimized. We use the optical simulation software FRED to design the import projection lens parameters, then the optimum transmissive projector configuration is obtained. In this thesis we discuss both size projector and medium-sized projector. By the ray tracing simulation processing, the light could project onto the detection screen. Then we analyze the simulation results to obtain the lumen defined by the American national standard institute (ANSI) and its uniformity of the projector. The value for the mini-size projector is above 93 lm and uniformity is 72.8, while that for the middle-size projector is above 260 and 47.9, respectively. The dimension for the mini-size projector is 15 cm × 7.5 cm × 2.5 cm. The later is compact, portable and low-cost and fits the commercial trend in future market.

APA, Harvard, Vancouver, ISO, and other styles

Dissertations / Theses on the topic 'Liquid crystal lenses design'

Create a spot-on reference in APA, MLA, Chicago, Harvard, and other styles