Search

The speed of most parallel-aligned liquid-crystal-on-silicon (LCoS) spatial light modulators (SLMs) is limited to the video rate of their drivers, which is a limitation for high-speed applications. However, the LCoS SLM presented here has a driver allowing a frequency range of up to 1011 Hz. Using the static phase modulation characterization and the static lookup table (LUT), the phase modulation characterization versus frequency shows that the SLM can operate at around 130 Hz or even higher for small phase changes and at 32 Hz for extreme phase changes. A dynamic calibration is carried out, and we propose a method allowing an increase of the frame rate while maintaining a maximum phase modulation of 2[pi]. Experimental results of dynamic diffractive optical elements displayed on the SLM at a frame rate of 205 Hz show that the dynamic LUT improves the reconstruction quality. OCIS codes: 220.1000, 050.1970, 230.6120, 230.3720.

The development of high-performance bottom-gate thin-film transistors (TFTs) with transparent zinc oxide (ZnO) channels is reported. The dry etching of the ZnO film in an Ar and C[H.sub.4] chemistry is developed to achieve a ZnO TFT back-plane for liquid-crystal display (LCD) with the required pattern accuracy.

We propose an optical configuration of a twisted nematic liquid crystal device driven by a fringe field for a single-cell-gap transflective display. The dark state of the reflective part is realized by a nematic liquid crystal layer with a twist angle of 63.6[degrees] and retardation of 194 rim, while a quarter-wave plate is inserted for the dark state of the transmissive part. Wavelength dispersion of the liquid crystal layer is suppressed by introducing a half-wave plate. Different directions of electric fields rotate liquid crystals to 15[degrees] for the bright state of the reflective part, but to -30[degrees] for that of the transmissive part. With the proposed configuration, we can realize a high-brightness single-gamma transflective display in a single-cell-gap structure without any in-cell retardation layers. OCIS codes: 230.0230, 230.3720.

A successive approximation method is proposed that is based on the conventional line-by-line-addressing. Many gray shades can be exhibited without flicker by using low-cost liquid crystal display drivers, which are designed to drive the pixels to either ON or OFF states in bilevel displays.

A novel simple control strategy to improve the ignition behavior of a cold cathode fluorescent lamp (CCFL) in digital-dimming mode is proposed in this paper. Due to restriking manipulation in the digital-dimming mode, the lamp life of CCFL is reduced substantially. For extending the lamp life, a digital-dimming controller with current spikes elimination technique is realized to reduce the high ignition voltage and eliminate the ignition current spike. The half-bridge resonant inverter is employed in the presented backlight system to assess the system performance. Complete analysis and design considerations are discussed in detail in this paper. Experimental results agree with the theoretical prediction. The overall efficiency of the system achieved at the rated power is over 84.9%. The ignition voltage is reduced about 30% without any lamp current spike that occurred under digital-dimming operation. Index Terms--Backlight, cold cathode fluorescent lamp (CCFL), digital dimming, electronic ballast, liquid crystal display (LCD).

Mueller matrix imaging polarimetry of liquid-crystal-on-silicon (LCoS) panels provides detailed information useful for the diagnosis of LCoS problems and to understand the interaction of LCoS panels with other projector components. Data reduction methods are presented for the analysis of LCoS Mueller matrix images yielding contrast ratio, efficiency, spatial uniformity, and the calculation of optimum trim retarders. The effects of nonideal retardance, retardance orientation, and depolarization on LCoS system performance are described. The white-state and dark-state Mueller matrix images of an example LCoS panel are analyzed in terms of LCoS performance metrics typical for red-green-blue wavelengths of 470, 550, and 640 nm. Variations of retardance, retardance orientation, and depolarization are shown to have different effects on contrast ratio, efficiency, and brightness. Thus Mueller matrix images can diagnose LCoS problems in a way different from radiometric testing. The calculation of optimum trim retarders in the presence of spatial variations is discussed. The relationship of the LCoS retardance in single-pass (from front to back) to the double-pass retardance (from entrance to exit) is established and used to clarify coordinate system issues related to Mueller matrices for reflection devices. OCIS codes: 120.2130, 120.5410, 230.3720, 260.5430.

We show experimental results for programmable polarization multiplexing of diffractive optical elements (DOEs) onto two liquid-crystal displays (LCDs). The first LCD encodes the two multiplexed phase-only diffractive optical elements. The second LCD acts as a pixelated polarization rotator to change the polarization state for each of these two DOEs. Although the system requires precise alignment, the DOE's and polarization angles are fully programmable. OCIS codes: 230.5440, 230.3720, 100.5090, 050.1970, 230.6120, 260.5430.

An innovative technique for reducing speckle noise and improving the intensity profile of the speckle correlation fringes is presented. The method is based on reducing the range of the modulation intensity values of the speckle interference pattern. After the fringe pattern is corrected adaptively at each pixel, a simple morphological filtering of the fringes is sufficient to obtain smoothed fringes. The concept is presented both analytically and by simulation by using computer-generated speckle patterns. The experimental verification is performed by using an amplitude-only spatial light modulator (SLM) in a conventional electronic speckle pattern interferometry setup. The optical arrangement for tuning a commercially available LCD array for amplitude-only behavior is described. The method of feedback to the LCD SLM to modulate the intensity of the reference beam in order to reduce the modulation intensity values is explained, and the resulting fringe pattern and increase in the signal-to-noise ratio are discussed. OCIS codes: 120.6160, 100.2650, 120.6150, 230.3720, 050.5080.

A demonstration of a field-induced birefringence method is conducted to determine the pretilt angle of a vertically aligned reflective liquid crystal display. A simple equation is deduced from the relationship between the prepolar angle and the phase retardation as a function of applied voltage.

We discuss a computer-generated hologram for encoding arbitrary complex modulation based on a commercial twisted-nematic liquid-crystal display. This hologram is implemented with the constrained complex modulation provided by the display in a phase-mostly configuration. The hologram structure and transmittance are determined to obtain on-axis signal reconstruction, maximum bandwidth, optimum efficiency, and high signal-to-noise ratio. We employed the proposed holographic code for the experimental synthesis of first-order Bessel beams. OCIS codes: 090.1760, 230.6120, 230.3720.

The parameters of a twisted-nematic liquid-crystal display (TN-LCD) are measured with no ambiguity when we measure the intensity transmittance of a system that simply consists of a TN-LCD, two polarizers, a quarter-wave plate, and a monochromatic beam. First we show analytically that the director angle can have a 90[degrees] ambiguity and the twist angle of the liquid-crystal molecules a 180[degrees] ambiguity. Then we uniquely measure the parameters by fitting the theoretical predictions to the intensity transmittance measured with and without the quarter-wave plate and by using the quasi local-adiabatic condition. The birefringence of the TN-LCD is measured next as a function of the applied voltage. We design a phase spatial light modulator by using the measured parameters and measure the phase delay of the output beam to excellent agreement with the theoretical prediction. OCIS codes: 160.3710, 230.3720, 230.6120, 260.1440.

The electro-optic performance properties, viewing angle characteristics, the relationship between pretilt angle versus load, and thermal aging study of the four-domain crystal is discussed. The optical simulations of the liquid crystal director orientation, viewing angle characteristics, and the contrast ratio of the four domains are described.

A stack of liquid-crystal displays is expected to reduce visual fatigue caused by a flat-panel three-dimensional (3DI display. We previously developed a compact depth-fused 3D (DFD) display by using a stack of two twisted-nematic (liquid-crystal) LC panels, but its viewing-angle characteristics and color reproducibility were not so good. Therefore recent wide-view LC panels should be used. We report calculated and measured luminance addition characteristics, which are essential for evaluating 3D display characteristics, of a stack of two multidomain LC panels. We found that LC panels with super in-plane switching, patterned vertical alignment, multiple vertical alignment, and continuous pinwheel alignment modes are suitable for DFD display application. OCIS codes: 230.3720, 120.2040.

The reflective bistable twisted nematic liquid-crystal displays (RBTN-LCDs) with a single front polarizer have been compensated by front half-wave or integer-wave plates or both. The compensation has been optimized through maximizing the contrast ratio. The optimized RBTN-LCDs with one or two retardation plates showed great improvement in contrast ratio. The wavelength-dependent reflectance, viewing-angle properties, and effects of the retardation variation of these optimized RBTNs with retardation compensation were also investigated. The simulation was carried out by using realistic parameters on RBTN modes that have retardation values from 0.30 to 0.85 [micro]m and a low contrast ratio. The viewing-angle properties did not change much before and after the retardation compensation. The reflectance varied little, but the contrast ratio varied significantly with the variation of the retardations of the bistable twisted nematic cells, for both compensated and uncompensated cases. It is shown that a high contrast ratio (100:1), high reflectance (30%), and low dispersion are possible for such RBTN-LCDs with proper retardation compensations. Black-white operations can be realized by compensating RBTN-LCDs. OCIS codes: 120.2040, 230.3720, 230.1150, 230.2090, 260.5430, 330.1690.

Mobility data for laterally crystallized poly-Si thin-film transistors (TFT) are presented and discussed.

We present an all-optical three-dimensional integral imaging projector. An optically addressed spatial-light modulator is used, which potentially provides better image resolution than the conventional CCD and liquid-crystal display pair. We present experimental results using a liquid-crystal light valve. OCIS codes: 110.6880,110.4190,100.6890.

INTRODUCTION This paper describes an experiment examining the relative effectiveness of two display technologies: a liquid-crystal display (LCD) and a conventional cathode-ray tube (CRT) of similar resolution and size. Within […], Visual search performance for tactical symbols was examined with liquid-crystal (LCD) and cathode-ray tube (CRT) displays. Twenty-four adult participants (19 men, 5 women; mean age 41 years) searched for navy tactical display symbols on a map background. LCD and CRT displays of similar size and resolution (52 cm diagonal, 1280 x 1024 pixels) were used. Viewing angle (0° vs. 60° of azimuth), set size, target color (blue, red, or white), target presence, and search type (feature vs. conjunction) were also manipulated. Participants showed reduced sensitivity for red and blue symbols viewed 600 off axis with the LCD relative to on-axis LCD, or to the CRT on or off axis. Colored symbols viewed off axis on the LCD produced longer response times in feature search and lower search efficiency in conjunction search. The results argue against the use of current LCD technology when off-axis viewing is likely and color coding is used.

A method is described for forming both transient and permanent, 1- and 2-D gratings in nematic liquid crystals.The method can easily be controlled by externally applied ac fields.

Two innovative line-crossover structures are described. They exhibit strengthened mechanical durability and reduced data-line signal delay because of a recessed air-gap line-crossover.

Research describing active matrix liquid crystal displays is presented. In particular experiments and simulations are developed to optimize the response times of such displays.

Research into the enhancement of thin-film transistors circuits using amorphous silicon is presented. The designs provide constant output current and have potential applications in active-matrix organic light emitting displays.

A new line-crossover structure using an air-bridge type line-crossover that decreases gate-data line capacitance is proposed as an alternative to the conventional oxide material with a dielectric constant of 3.9.

Research describing holographic gratings prepared by biphotonic processes on liquid crystal films is presented. In particular polarization and intensity recordings by irradiation with incoherent blue and red light are investigated.

Research describing the polarization states of a liquid crystal cell are presented. In particular perfect polarization conversion conditions are investigated by means of a Mueller matrix.

A novel operating method for a liquid crystal display device is reported.

A new spectroscopic ellipsometry method is presented for liquid crystal (LC) display twist angle and retardation measurement. By varying the polarizer and analyzer angles only, a transmission spectrum containing null transmission at some particular wavelengths can be obtained.

Photinduced liquid crystal alignment is examined.

A simple method to determine the cell gap and twist angle in reflective liquid crystal displays is reported.

Research into phosphor liquid crystal displays is presented.

Plasma addressed liquid crystal displays are examined.

A new study uses a parameter space method to develop a new 0 deg-360 deg bistable twisted nematic mode liquid crystal display.

A new study uses the parameter space approach to investigate the optical properties of reflective bistable nematic liquid crystals.

A new study describes how to form a vertically aligned 4-domain nematic liquid crystal display cell.

A new study seeks to control spot generation by analysing the spot generation properties of a liquid crystal spatial light modulator, focusing on the effect of nonlinearity.

A model of a reflective bistable twisted nematic liquid crystal display is studied by detailed numerical simulation. The study shows that large wavelength dispersion in the reflection coefficient of such displays cause the optimal mode to have a small value of d delta n, around 0.2 mu m.

A parameter space approach is used to optimize a Pi/2 and 5Pi/2 twist bistable nematic liquid crystal cell.

A new study examines the effect of H2, He, NH3 and N2 plasma treatment on the surface of a silicon nitride gate insulator on the performance of a hydrogenated amorphous silicon thin film transistor.

A theoretical model for describing properties of a liquid crystal display is presented.

Research was conducted to make an accurate determination of the temperature and frequency dependent smectic C biaxial permittivity tensor. The calculation of the dielectric permittivities of a smectic C material was carried out through two different alignment geometries and then interpreted using continuum theory. The simultaneous measurement of smectic C elastic constant and the biaxial permittiities is allowed which indicates that the approach is applicable to both racemic and chiral ferroelectric liquid crystal materials over a wide frequency range.

Research was conducted to examine the optics of reflective bistable twisted nematic (BTN) liquid crystal display for general values of twist angle and polarizer angle. The other important properties of the reflective BTN such as the peak light efficiency and the wavelength dispersion of two bistable states were also investigated. Results are useful for the further design and optimization of the reflective BTN displays.