Browsing by Subject "Display devices"

Now showing 1 - 8 of 8

Open Access
2D material liquid crystals for optoelectronics and photonics
(Royal Society of Chemistry, 2017) Hogan, Ben T.; Kovalska, Evgeniya; Craciun, Monica F.; Baldycheva, Anna
The merging of the materials science paradigms of liquid crystals and 2D materials promises superb new opportunities for the advancement of the fields of optoelectronics and photonics. In this review, we summarise the development of 2D material liquid crystals by two different methods: dispersion of 2D materials in a liquid crystalline host and the liquid crystal phase arising from dispersions of 2D material flakes in organic solvents. The properties of liquid crystal phases that make them attractive for optoelectronics and photonics applications are discussed. The processing of 2D materials to allow for the development of 2D material liquid crystals is also considered. An emphasis is placed on the applications of such materials; from the development of films, fibers and membranes to display applications, optoelectronic devices and quality control of synthetic processes. © 2017 The Royal Society of Chemistry.
Open Access
Design of a 360-degree holographic 3D video display using commonly available display panels and a paraboloid mirror
(SPIE, 2017) Onural, Levent
Even barely acceptable quality holographic 3D video displays require hundreds of mega pixels with a pixel size in the order of a fraction of a micrometer, when conventional flat panel SLM arrangement is used. Smaller pixel sizes are essential to get larger diffraction angles. Common flat display panels, however, have pixel sizes in the order of tens of micrometers, and this results in diffraction angles in the order of one degree. Here in this design, an array of commonly available (similar to high-end mobile phone display panels) flat display panels, is used. Each flat panel, as an element of the array, directs its outgoing low-diffraction angle light beam to corresponding small portion of a large size paraboloid mirror; the mirror then reflects the slowly-expanding, information carrying beam to direct it at a certain exit angle; this beam constitutes a portion of the final real ghost-like 3D holographic image. The collection of those components from all such flat display panels cover the entire 360-degrees and thus constitute the final real 3D table-top holographic display with a 360-degrees viewing angle. The size of the resultant display is smaller compared to the physical size of the paraboloid mirror, or the overall size of the display panel array; however, an acceptable size table top display can be easily constructed for living-room viewing. A matching camera can also be designed by reversing the optical paths and by replacing the flat display panels by flat wavefront capture devices.
Open Access
Integral imaging using phase-only LCoS spatial light modulators as Fresnel lenslet arrays
(Optical Society of Amercia, 2011-10-27) Ÿontem, A. O.; Onural, L.
We present a digital integral imaging system. A Fresnel lenslet array pattern is written on a phase-only LCoS spatial light modulator device (SLM) to replace the regular analog lenslet array in a conventional integral imaging system. We theoretically analyze the capture part of the proposed system based on Fresnel wave propagation formulation. Because of pixelation and quantization of the lenslet array pattern, higher diffraction orders and multiple focal points emerge. Because of the multiple focal planes introduced by the discrete lenslets, multiple image planes are observed. The use of discrete lenslet arrays also causes some other artifacts on the recorded elemental images. The results reduce to those available in the literature when the effects introduced by the discrete nature of the lenslets are omitted. We performed simulations of the capture part. It is possible to obtain the elemental images with an acceptable visual quality. We also constructed an optical integral imaging system with both capture and display parts using the proposed discrete Fresnel lenslet array written on a SLM. Optical results when self-luminous objects, such as an LED array, are used indicate that the proposed system yields satisfactory results.
Open Access
Lateral and vertical heterostructures of h-GaN/h-AlN: electron confinement, band lineup, and quantum structures
(American Chemical Society, 2017-11) Onen, A.; Kecik, D.; Durgun, Engin; Çıracı, Salim
Lateral and vertical heterostructures constructed of two-dimensional (2D) single-layer h-GaN and h-AlN display novel electronic and optical properties and diverse quantum structures to be utilized in 2D device applications. Lateral heterostructures formed by periodically repeating narrow h-GaN and h-AlN stripes, which are joined commensurately along their armchair edges, behave as composite semiconducting materials. Direct-indirect characters of the fundamental band gaps and their values vary with the widths of these stripes. However, for relatively wider stripes, electronic states are confined in different stripes and make a semiconductor-semiconductor junction with normal band alignment. This way one-dimensinonal multiple quantum well structures can be generated with electrons and holes confined to h-GaN stripes. Vertical heterostructures formed by thin stacks of h-GaN and h-AlN are composite semiconductors with a tunable fundamental band gap. However, depending on the stacking sequence and number of constituent sheets in the stacks, the vertical heterostructure can transform into a junction, which displays staggered band alignment with electrons and holes separated in different stacks. The weak bonds between the cations and anions in adjacent layers distinguish these heterostructures from those fabricated using thin films of GaN and AlN thin films in wurtzite structure, as well as from van der Waals solids. Despite the complexities due to confinement effects and charge transfer across the interface, the band diagram of the heterostructures in the direct space and band lineup are conveniently revealed from the electronic structure projected to the atoms or layers. Prominent features in the optical spectra of the lateral composite structures are observed within the limits of those of 2D parent constituents; however, significant deviations from pristine 2D constituents are observed for vertical heterostructures. Important dimensionality effects are revealed in the lateral and vertical heterostructures.
Open Access
Metal-dielectric-metal plasmonic resonators for active beam steering in the infrared
(Optical Society of America, 2013) Battal, E.; Okyay, Ali Kemal
Active beam-steering devices near the optical frequencies have long been sought after due to their applications in communication, defense, and display technologies; however, the challenge lies in achieving actively tunable structures near these frequencies. An array of metal-dielectric-metal plasmonic resonators is demonstrated as a dynamic beam-steering device to operate at midinfrared wavelengths. We numerically demonstrate continuous-angle beam steering of 8.75° by making use of tunable properties of silicon as the active dielectric. The proposed device achieves a refractive index insensitive divergence angle and it operates in a 650 nm wide spectral window around 10 μm wavelength. The results of this Letter pave the way to exploiting active beam steering in various applications at midinfrared wavelengths.
Open Access
A new approach to holographic video imaging: principles and simulations
(SPIE, 1992) Onural, Levent; Bozdağı, Gözde; Atalar, Abdullah
As the importance of 3-dimensional information displays in many fields increases, more attention is given to holographic displays. Different kinds of holographic displays are reported in the literature, but the resolution of the available display media is not sufficient to support the extraordinary spatial detail of holograms. In this paper, we propose a new acousto-optical holographic display device which solves significantly the display resolution and the refreshing problems that are common to available holographic displays. The technique is based on the reproduction of the hologram using traveling surface waves. The SAW device that is used as the medium of display has an array of electrodes attached to it. An electrical signal applied to one of these electrodes generates an acoustical wave propagating on the surface of the crystal where the electrodes are the sources. If signals are applied to all of the electrodes simultaneously, propagating waves from the electrodes superpose to form a time-varying surface field pattern on the crystal. This pattern, at a specific time, forms the hologram. The signals which should be applied to the electrodes, in order to have a specified field pattern on the crystal at a specified time instant are found through a mathematical inversion relation. The inversion relationship is derived from the underlying physics. Computer simulations of the proposed TV display show that the proposed system will work as desired. In addition, our preliminary studies show that the proposed system can be constructed with the available acoustical, optical, electronic technology, and with the application of digital signal processing techniques.
Open Access
Predicting pilot behavior in medium-scale scenarios using game theory and reinforcement learning
(American Institute of Aeronautics and Astronautics Inc., 2014) Yildiz, Y.; Agogino, A.; Brat, G.
A key element to meet the continuing growth in air traffic is the increased use of automation. Decision support systems, computer-based information acquisition, trajectory planning systems, high-level graphic display systems, and all advisory systems are considered to be automation components related to next generation (NextGen) air space. Given a set of goals represented as reward functions, the actions of the players may be predicted. However, several challenges need to be overcome. First, determining how a player can attempt to maximize their reward function can be a difficult inverse problem. Second, players may not be able to perfectly maximize their reward functions. ADS-B technology can provide pilots the information, position, velocity, etc. of other aircraft. However, a pilot has limited ability to use all this information for his/her decision making. For this scenario, the authors model these pilot limitations by assuming that pilots can observe a limited section of the grid in front of them.
Open Access
Trends in molecular design strategies for ambient stable n-channel organic field effect transistors
(Royal Society of Chemistry, 2017) Dhar, J.; Salzner, U.; Patil, S.
In recent years, organic semiconducting materials have enabled technological innovation in the field of flexible electronics. Substantial optimization and development of new π-conjugated materials has resulted in the demonstration of several practical devices, particularly in displays and photoreceptors. However, applications of organic semiconductors in bipolar junction devices, e.g. rectifiers and inverters, are limited due to an imbalance in charge transport. The performance of p-channel organic semiconducting materials exceeds that of electron transport. In addition, electron transport in π-conjugated materials exhibits poorer atmospheric stability and dispersive transient photocurrents due to extrinsic carrier trapping. Thus development of air stable n-channel conjugated materials is required. New classes of materials with delocalized n-doped states are under development, aiming at improvement of the electron transport properties of organic semiconductors. In this review, we highlight the basic tenets related to the stability of n-channel organic semiconductors, primarily focusing on the thermodynamic stability of anions and summarizing the recent progress in the development of air stable electron transporting organic semiconductors. Molecular design strategies are analysed with theoretical investigations.