V. A. Konovalov

P‐25: An Accurate Spectral Method for Measuring Twist Angle of Twisted Cells with Rubbed and Grooved Surfaces

Accurate optical method for measuring twist angle in TN LC cells is presented. Deviation of the measured values for different orientations of the cell and polarizes have been analyzed. The method allows to determine twist angle with high accuracy for cells with rubbed surfaces as well as for cells where at least one surface is corrugated.

44.2L: Multi-Domain Vertically Aligned Mode

We considered electrooptical properties of twisted and non-twisted vertically aligned (VA) nematic liquid crystals with the main aim to improve their viewing angle, response speed and brightness. Several modes appropriate for applications in multi-domain and amorphous VA textures are outlined. A new method to obtain multi-domain homeotropic alignment is developed and electrooptic properties of experimental samples are investigated.

Pixel design and electro-optic properties of multi-domain vertically aligned mode

Multi-domain texture is obtained in VA LCD by depositing dielectric black matrix on the color filter substrate above the electrode. It is shown, that without additional technological operations wide viewing angle and high brightness can be achieved.

6.2: Lifetime of Single Panel LCOS Imagers

The lifetime of the TN45 effect used in single panel LCOS imagers has been demonstrated to be 20,000 hours at 2 Mlux illumination. This paper will document the test methods used to determine this lifetime. The variation in lifetime under different illumination conditions will also be discussed.

Mechanism and electro‐optic properties of multidomain vertically aligned mode LCDs

— We considered the electro-optical properties of twisted and non-twisted modes in vertically aligned (VA) nematic liquid crystals with the main objective of improving their viewing angle, response speed, and luminance. Several modes appropriate for applications in multidomain and amorphous VA textures are outlined. Mechanisms of multidomain texture formation in displays with dielectric patterns between the electrodes are analyzed by computer simulations and verified with experimental samples. It is shown that by depositing dielectric patterns on the electrodes it is possible to fabricate multidomain liquid-crystal displays without inversion of gray levels, sacrificing only 20% of the luminance of conventional single-domain displays.

Studies of the Anchoring Energy of Nematics on Grooved Surfaces

Abstract Previously we developed optical method enabling measurements of the liquid crystal twist angle in the cells with grooved surfaces. In this work azimuthal anchoring energy of a liquid crystal to a surface is estimated by measuring the deviation of the twist angle of the liquid crystal from the angle defined by direction of liquid crystal alignment on one rubbed and one grooved surfaces substrates. It was found that the twist angle in the cells depends not only on the parameters of the grooves, but also strongly depends on the material covering the grooves.

SSFLC Polarization Switch for Zeeman Laser Stabilization Loop

Abstract Ferroeleciric liquid crystals (FLC) as light modulators in the stabilization system of a Zeeman laser increase the quality of stabilization due to the high switching speed and make the whole system very compact. We analyze the operation of the optical part of such a stabilization system and derive optimum values of the FLC cell parameters. Properties of available liquid crystals and their temperature dependence are considered as well as, in particular, the influence of a slight ellipticily of the laser radiation.

A lifetime model for LCOS panels under intense illumination

— The mechanisms of photochemical reactions occurring during the operation of LCOS panels under intense illumination are analyzed. Regardless of the liquid-crystal-mixture formulation, light may generate radicals in the liquid crystal and the polyimide alignment layer. The interaction of these radicals modifies the PI surface and causes alignment degradation. Using kinetic equations for these processes, a lifetime model for the LCOS panels is developed. This new model of lifetime dependence versus light intensity is found to be in agreement with experimental data. This model verifies the TN LCOS panel lifetime to be in excess of 50,000 hours for RPTV applications.

Properties and mechanism of multi-domain vertically aligned mode on a grid surface

Electro-optical properties of grid-aligned multi-domain (GAMD) textures in homeotropi-cally aligned nematic liquid-crystal displays have been studied as a function of grid parameters. It is experimentally verified that with higher height and smaller pitch of the grid, a more-stable multi-domain structure can be obtained. To predict the grid properties and the mechanism of their action, both computations and experimental results are presented. The weak-anchoring conditions are assumed in the computations on the base of the measured anchoring-strength data to obtain more reliable parameters. A test liquid-crystal cell has been prepared after adjusting the grid parameters, and it has shown very high gray-level stability, a nice viewing angle, and fast response.