Optical Display Devices Research Articles

Spectroscopic investigation and optical characterization of Eu3+ ions in K–Nb–Si glasses

This paper reports on the effect of concentration of Eu3+ ions in K2O–Nb2O5–SiO2–Eu2O3 (KNbSiEu) glasses prepared by the melt quenching technique. By using the Judd–Ofelt (JO) theory, the intensity parameters Ωλ (λ=2, 4, 6) have been determined from the absorption and emission spectra of Eu3+ ions under different constraints. The radiative properties of some of the excited states of Eu3+ ions have been calculated. The decay curves of 5D0 level exhibited single exponential for all the Eu3+ ions concentrations. From these results, it is suggested that the strong red emission at 616nm corresponding to the 5D0→7F2 transition could be used for the development of optical display devices.

Enhancement of diffuse reflectance using air tunnel structure

Submicrometer air gap structure has formed on diffuse reflection structure to improve light reflectance. Covering polymer or liquid on a diffuse reflector to make optical components induces the severe decrease of the total reflectance, since the diffuse reflected angle of some light rays is larger than the critical angle and the rays travel to the medium until meeting a proper small incident angle. The reflectance drops to 68% of the original value with just a polymer coating on the diffuse reflector. The formation of an air tunnel structure between the polymer layer and the diffuse reflector makes a symmetrical reflective index matching state and recovers 95% of the original reflectance. Due to the simple fabrication process and the chemical stability, the structure can be applied to various optical components and reflective display devices.

Influence of Bi3+ as a sensitizer and SiO2 shell coating as a protecting layer towards the enhancement of red emission in LnVO4: Bi3+, Eu3+ @ SiO2 (Ln=Gd, Y and Gd/Y) powder phosphors for optical display devices

Enhanced red luminescence in LnVO4: Bi3+, Eu3+ @ SiO2 phosphors has been improved mainly in three stages by investigating the effects of: (i) host composition (Gd, Y and Gd/Y), (ii) co-doping Bi3+ as a sensitizer and finally (iii) SiO2 shell coating. XRD data revealed that the produced phosphors possess crystalline, pure phase with tetragonal structure. Silica coating on phosphor particles have been characterized by SEM/EDAX, TEM, PL and with the presence Si–O–Si, Si–O vibrational modes from the FT-IR spectra. Absorption band edges due to VO43−, shifted to higher wavelength with Bi-concentration, owing to the presence of Bi–O bond in addition to V–O. The emission intensities of 5D0→7F2 transition are stronger than 5D0→7F1; indicating the lower inversion symmetry near Eu3+, ions. Red emission intensity due to the efficient energy transfer from VO43− to Eu3+ via Bi3+ ions in Y0.949VO4: Bi3+0.001, Eu3+0.05 phosphor was improved significantly, i.e. 1.6 times compared to Y0.95VO4: Eu3+0.05. This was further enhanced 2.25 times by SiO2 shell coating. Thus, Y0.949VO4: Bi3+0.001, Eu3+0.05 @ SiO2 are suggested to be a promising red phosphor for application in display devices or lighting.

Film based on Y2O3:Eu3 + (5 mol% of Eu3 +) for flat panel display

This paper reports on Y2O3:Eu3+ containing 1mol% of Ag0 nanoparticle films recovered with a SiO2 layer by using glass foil as a substrate for a possible optical display device application. The obtained film showed an intense emission at 612nm due to the Eu3+5D0→7F2 hypersensitive transition, a high transmittance in that emission range, an excellent optical quality, and a high absorption only below 300nm. Moreover, despite the presence of the SiO2 layer used to improve the phosphor adhesion on Corning® foil substrates, the intensity ratios between the emissions assigned to Eu3+5D0→7F2 (dipole electric transition) and 5D0→7F1 (dipole magnetic transition) were not affected by it. The x and y coordinate values found in the 1931 Commission Internationale de l'Eclairage Chromaticity Diagram for this film reveal that it has a suitable pure red color emission for optical displays devices.

Synthesis and fluorescence properties of novel 1,10‐phenanthroline‐functionalized polyaryletherketone and its rare earth complexes

Abstract1,10‐Phenanthroline‐functionalized polyaryletherketone (PPEK) was synthesized by the amidation reaction of 5‐amino‐1,10‐phenanthroline with polyaryletherketone containing pendant acyl chloride groups. Subsequently, a series of novel rare earth coordination polymers (with rare earths Eu3+, Tb3+, Sm3+ and Dy3+) were prepared, using PPEK as macromolecular ligand and the small 1,10‐phenanthroline (Phen) molecule as synergistic ligand. Their structures were characterized using Fourier transform infrared spectroscopy, elemental analysis and X‐ray diffraction, which confirmed that both PPEK and Phen participated in the coordination reaction with the rare earth ions, and that the rare earth ions could disperse homogeneously in the polymer matrix. The rare earth coordination polymers were soluble in polar solvents such as N,N‐dimethylformamide, N,N‐dimethylacetamide and N‐methylpyrrolidone, and could be easily cast into transparent tough thin films. Fluorescence measurements indicated that all the coordination polymers exhibited the intense characteristic fluorescence of the corresponding rare earth ions under ultraviolet excitation, showing their application potential in optical display devices. Copyright © 2010 Society of Chemical Industry

Optical Properties of CdS–PVA Nanocomposites

Semiconductor–polymer nanocomposites, with good control over the nanoparticle size and their dispersion within the polymer matrix, can have applications in many optical and luminescent display devices. Cadmium sulphide (CdS) is the most popular semiconductor nanoparticle exhibiting size dependent properties due to its large exciton binding energy and its suitability for large scale production. The nanoparticles need to be passivated against aggregation with suitable capping agents, without sacrificing the desirable properties like transparency and flexibility of the polymer. Cadmium sulphide nanoparticles capped with polyvinyl pyrrolidone (PVP) are synthesized using cadmium nitrate (Cd(NO3)2) and hydrogen sulphide (H2S) as Cd2+ and S2– sources, respectively. CdS particles with sizes in the range of 5–6 nm are prepared in methanol and the solvent is removed using a rotary evaporator. CdS powder is dispersed in polyvinyl alcohol (PVA) solution with dimethyl formamide (DMF) as solvent to get (PVP–CdS)–PVA nanocomposite film of about 0.2 mm thickness. This has been characterized by powder X-ray diffraction (XRD), optical absorption studies, transmission electron microscopy (TEM), differential scanning calorimetry (DSC) and photoluminescence (PL). Particle size does not change due to incorporation in the polymer matrix and the polymer retains its transparency and flexibility. The nanocomposite shows good photoluminescence property with stronger band edge emission than defect related emission. The latter could be quenched completely by optimizing the PVP content. Irradiation of the nanocomposite with 8 MeV electrons at a dose of 100 kGy could effectively quench the defect related emission.

Signal processing issues in diffraction and holographic 3DTV

Image capture and image display will most likely be decoupled in future 3DTV systems. Due to the need to convert abstract representations of 3D images to display driver signals, and to explicitly consider optical diffraction and propagation effects, it is expected that signal processing issues will be of fundamental importance in 3DTV systems. Since diffraction between two parallel planes can be represented as a 2D linear shift-invariant system, various signal processing techniques naturally play an important role. Diffraction between tilted planes can also be modeled as a relatively simple system, leading to efficient discrete computations. Two fundamental problems are digital computation of the optical field arising from a 3D object, and finding the driver signals for a given optical display device which will then generate a desired optical field in space. The discretization of optical signals leads to several interesting issues; for example, it is possible to violate the Nyquist rate while sampling, but still achieve full reconstruction. The fractional Fourier transform is another signal processing tool which finds applications in optical wave propagation.

Polypyrrole conductive polymer characteristics as an optical display device

The redox dynamic of electrochemically prepared thin films of polypyrrole is studied. A semi-empirical formula to explain the redox behavior is formulated and it seems applicable to the reduction dynamic. The redox dynamic is dominated by a diffusion process, depending on the relation between the film thickness and the rise time (t 1/2 ) of the reduction process. The diffusion coefficient, D, was measured to be 2 × 10 -9 cm 2 /sec for perchloride (ClO 4 - ) anion dopant and 1.1 x 10 -9 cm 2 /sec for para-toluenesulfonate (PTS - ) anion dopant. The polypyrrole films exhibited a color change during the oxidation and reduction processes. The electrooptical properties of these films are studied.

Cathodoluminescence studies of materials for use in optical display devices

Cathodoluminescence studies have been carried out for many years for the assessment of semiconductor materials such as Gallium Arsenide, Gallium Phosphide and Silicon. These investigations have relied on utilising the focused electron beam of an SEM to excite luminescence. This is subsequently directed through a monochromator to allow spectroscopy and also the acquisition of high resolution images showing the spatial distribution of the optically active centres (≥0.5μm).The recent growth of research in the production and characterisation of optically active materials and devices such as 3/5 or 2/6 LED's for the use in visible display products has fuelled the use of CL to determine the optical properties on a scale that is superior to that available by PL. In addition characterisation of the optical properties as a function of electron beam characteristics, dosage and at temperatures between 4.2K and 300K are possible.Results from GaN epilayers will be shown that indicate that two separate phases (alpha and beta) can be identified by the position of the Bound Exiton luminescence and that this luminescence is distributed randomly through the sample. The sites responsible for this luminescence are less than 0.5μm in size.

Apparatus for electronic teaching accompaniment and practice of music, which is independent of a played musical instrument

The invention relates to an electronic teaching, accompaniment and practice music apparatus which is independent of a played musical instrument. The apparatus includes devices for digital sound production, tempo setting, accompaniment, operation and input of digital note data, which are connected by means of a control unit, which is connected with an electro-acoustical device for acoustical reproduction of the note sequences corresponding to the input piece of music via a digital-analog converter. There is an optical display device which is connected with a piano keyboard or a guitar fingerboard or represents these, for optical display of the note sequences played.

Voice‐training apparatus

In an apparatus for voice training, on several points of a student's body measuring devices are provided, which are connected to optical display devices. At each of these measuring devices, a pressure sensor amplifier is connected with an analog multiplexer, and a sound-pressure measuring device is directly connected to the respective display device.

Throwing Light on Data-Taking

Throwing Light on Data-Taking

Heavy Metal Fluoride Glasses for Optical Applications

ABSTRACTGreat progress has been made in optical device technology over the past decade. This progress brings a host of new services which include voice, data and visual communications. The realization of low loss optical fibers which give rise to long distance optical communication and the growth in information processing through computer technology will lead to an accelerating growth in the utilization of light guides and light wave communication systems. Heavy metal fluoride glasses have proved to be excellent hosts for both rare earth and 3d transition metal ions. In addition, their potential as light guides is at present unexcelled. This glass is especially promising for optical display devices, laser hosts, and electroluminescence panels. Numerous defects and impurities can be incorporated in the glass which absorb or emit light. Through optical studies of rare earth ions such as Er3+, Ho3+, Nd3+ and Pr3+ it is possible to investigate the multiphonon emission rate for optical transitions in the heavy metal fluoride materials. It is found that these particular materials have a much lower multiphonon rate than oxide glasses. This makes them attractive for room temperature devices. When 3d transition metal ions are incorporated into heavy metal fluoride glasses, the optical properties are similar in many cases to those in crystals. Inhomogeneous broadening of the absorption and emission bands occurs in the glass, but the lifetimes and oscillator strengths of the transitions in glass and crystals are of the same magnitude. Radiation damage of glasses can be detrimental to long range optical communication. It is found that the heavy metal fluoride glasses damage by the photochemical mechanism which is also dominant in highly ionic materials. Optical absorption and electron spin resonance measurements have been utilized to identify the types of radiation induced defects in these materials.

Health & safety issues in computer graphics (Panel Session)

Health & safety issues in computer graphics (Panel Session)

Recent Optical Display Devices and It's Application

Recent Optical Display Devices and It's Application

Ferroelectric films and their device applications

Recent reseach on ferroelectric films is discussed, with emphasis on preparative problems, optimization of film structure and of electrical properties and application in devices. Rapid progress has been made in each of these research areas and this fact, together with the emergence of certain new materials such as polyvinylidene fluoride (PVF 2), is increasing the variety of possible applications to solid state devices. Typical examples considered here include microwave capacitors, thermistor bolometers, pyroelectrics, piezoelectric transducers, memories and optical display devices. The present state of the art for these applications and materials development needed for further progress are reviewed.