Igor N. Kompanets

Light modulation characteristics of a single-polarizer electro-optical cell based on polymer dispersed ferroelectric liquid crystals

Features of the light passing through a single-polarizer electro-optical cell based on a uniaxially oriented film of a polymer dispersed ferroelectric liquid crystal have been studied. The optical response as a function of the applied electric field is shown to depend on the cell geometry. A detailed analysis is presented of the dependence of the maximum light transmission, modulation depth and contrast ratio on the angle between the light polarization and the film orientation direction, on its optical anisotropy and on the molecular tilt angle. An approximate formula is proposed to estimate the highest attainable contrast. Parameters under study have been measured for PDFLC films varying in optical anisotropy value. The experimental results prove to be in good agreement with theoretical estimations.

Behaviour of Nematic Liquid Crystals in Inhomogeneous Electric Fields

Abstract The behaviour of homogeneously aligned nematic liquid crystal layers in inhomogeneous electric fields has been theoretically and experimentally investigated. The variation of the phase retardation of monochromatic light along nematic liquid crystal layer at the edges of a cell electrode has been obtained. Anisotropic character of the resolution of liquid crystal devices is shown.

Surface and volume bistability in ferroelectric liquid crystals

We call the bistabifity of ferroelectric liquid crystal (FLC) cells as the surface bistability (SB), if the dispersion part of anchoring energy is responsible for this type of bistabiity. SB was predicted theoretically [1] and investigated experimentally [2-4] .It was shown, that SB there exists in SSFLC cells possessing the bookshelf structure of smectic C layers [2] and SB there exists only in limited region of multidimensional space of cell and driving voltage parameters [3]. Anchoring energy of FLC with solid surface for SB structures is [4]: 102 iO erg / cm2 On the other hand there exists the volume bistability (VB), which have been observed by us recently in thick (15 mkm and more) layers of new FLC compositions [5].VB is a special phenomenon caused only with stereo chemical nature of the FLC composition and quite independent upon surfaces. In this work we would try: to found the physical principle for experimental measurement of an average free energy density of ferroelectrics, -to describe manifestations for both SB and VB, - to compare SB and VB from point of view their free energy parameters.

Gray-scale FLC for SLM and displays

A new principle of continuous gray scale for passively addressed FLC displays and SLM matrices is proposed. It is based on the multistability effect in C*FLC. Conditions of its exhibition are defined. Experimental results for FLC cells and the laser beam intensity attenuator are given.

Dynamic parameters of electrically controlled light scattering in helix FLC cells

— The light-scattering structures in monomeric FLCs have been considered and a mechanism for the scattering on transient domains in the helix layers has been proposed. An optical response with a bistable characteristic of light scattering and transmission was realized at a defined electrical pulse regime and boundary conditions in electro-optical FLC cells. The total time of the scattering switching on and switching off is less than 400 μsec at ±36 V. They are quite fast, and FLC cells are quite transparent to be used in a stack of 30–100 light-scattering shutters for a volumetric screen of a 3-D display.

Light modulation characteristics of single-polarizer PDFLC films

Abstract Typical textures of ferroelectric liquid crystal droplets dispersed in a thermoplastic matrix are presented. Uniaxially aligned droplets with wavy deformed smectic layers are effective light scattering polarizers, the direction of which can be reoriented by an applied electric field. We have studied theoretically and experimentally the dependencies of the light modulation characteristics of a single polarizer electrooptical cell based on a planar-oriented film of polymer dispersed ferroelectric liquid crystals both on the geometry of the cell and the material parameters.

Low voltage and high optical quality polymer dispersed FLC films

Abstract Polymer dispersed ferroelectric liquid crystal films were prepared and investigated. The saturation voltage less than 10 V, the polarized light transmittance 628%at the contrast ratio 45:1 or 75%at the contrast ratio 10:1 were reached.

P‐120: Low Voltage FLC for Fast Active Matrix Displays

The process of FLC director reorientation in alternating electric field is considered for the case, when interaction of FLC molecules with the substrates results in portion unwinding of helix structure and domain walls motion. Hysteresis-free electrooptical response as fast as 30÷70 μs was achieved in FLC cells of 1.0 and 1.3 μm thickness at the electric field intensity of 1.0÷2.0 V/μm. This result is very important for the practical use of FLC materials in fast active matrix displays.

11.1: Invited Paper: Ferroelectric Liquid Crystals as a Material for Volumetric Displays

Three types of electrically controlled light scattering distinguished on the physical mechanism were studied in monomeric FLC compositions at different boundary conditions and electrical pulse regimes. The total time of scattering switching on and switching off was less than 150, 250 and 500 us for different scattering types. They are rather fast to be used in a volumetric screen based on a stack of 30–100 light-scattering shutters.

Advances in FLC electro-optics and FLCD prospects

Advances in the field of studying the electrooptics of ferroelectric liquid crystal and possibilities of their practical use are considered. Liquid crystal compositions are developed with steady bistable and multistable properties and high multiplex ability for composing and displaying blocks of both the binary and analog information in fast spatial light modulators and high resolution information displays. Liquid crystal cells are created with electrooptical response time of a few microseconds.