Tatsuo Masumi

Superconducting Bi-Sr-Ca-Cu-O Thick Films by the Sol-Gel Method

Superconducting thick films of the Bi-Sr-Ca-Cu-O system were prepared on MgO(100) substrates by the sol-gel method. A smooth thick film showing Tco of 117 K and Tce of 84 K has been synthesized by sintering at 870°C for 2 h. The thick films sintered at above 860°C showed the c-axis perpendicular to the substrate.

Alignment and Electro-Optic Properties of SSFLC Cells Aligned by Obliquely Evaporated SiO Films

Abstract Alignment and electro-optic properties of SSFLC cells aligned by 85° obliquely evaporated SiO films are investigated. The vacuum condition of the SiO evaporation was found to have a great effect on the alignment. The SiO film evaporated in a high vacuum gives a poly-domain alignment which is reformable into a mono-domain by the application of a strong electric field. The cell with the reformed alignment shows an almost perfect memory and a high contrast in a specific temperature range, which suggests that the cell is aligned in the so-called “uniform” state. A cell with the SiO film by low vacuum evaporation shows an imperfect memory and a very low contrast. The alignment of this cell is confirmed to be in the “twisted” state. The strong electric field gives no influence on the alignment of this cell. Possible relation between the obtained alignment and the observed SiO columnar structure is discussed.

Physical Properties of Ferroelectric Liquid Crystals Incorporating a Boron Atom

Abstract Physical properties of a new type of ferroelectric liquid crystal incorporating a boron atom have been studied. Spontaneous polarization, tilt angle and chiral pitch of the new ferroelectric liquid crystals are compared with those of other types of ferroelectric liquid crystals. The alternation of the Ps direction and the twist sense is observed as the chiral center is moved further away from the core.

Ferroelectric liquid crystal cell having gray scale for high-speed spatial light modulator

Gray scale was obtained with a ferroelectric liquid crystal (FLC) cell in which the twisted state of FLC molecules is gradually unwound by an applied voltage. The cell has an extinction ratio of 60 at 632. 8 nm and a response time of 300 jtsec. A spatial light modulator (SLM) with 256 x 256 pixels was fabricated by incorporating the FLC cell with an amorphous silicon thin film transistor array. This offers us a promising technology to realize a FLC-SLM with gray scale a fast frame time of 300 psec and a pixel number as large as 1000 x 1000.

Effects of polymer matrix on electro-optic properties of liquid crystals mixed with polymer

The presence of hysteresis in transmittance-voltage characteristics of liquid crystal mixed with polymer (LCMP) has been the main cause for the residual image of LCMP display devices. This hysteresis is regarded to originate in the interaction between liquid crystal material and matrix polymer. The molecular motion of the matrix polymer of LCMP is varied systematically by changing the monomer and photo-initiator content. The hysteresis of LCMP decreases as the elastic modulus of matrix polymer decreases. It has been found quite effective to lower the elastic modulus of matrix polymer in reducing the hysteresis of LCMP.

Preparation of Superconducting Bi-Sr-Ca-Cu-O Films by the Organometallic Route Using Plasma Oxidation

In the process of preparing superconducting films from organometallic compounds, plasma oxidation has been attempted on an organometallic compound film as a method of decomposing organic components included in the starting materials. Organic components were removed by plasma oxidation more smoothly than by the conventional thermal decomposition method. Plasma oxidation encouraged the growth of microcrystals in the resulting compound. A smooth 0.2 µm film of Bi2Sr2Ca1Cu2Ox without any cracks was obtained. The film showed the superconducting transition temperature Tce=78 K.

Light Scattering Properties of Polymer Dispersed Liquid Crystals

Abstract The Stein-Rhodes Model (SR model) which explains light scattering by anisotropic spheres is applied to the light scattering phenomenon in Polymer Dispersed Liquid Crystals (PDLC). Comparison of Hv light scattering capability obtained by both the experiment and the theoretical model reveals that, especially in a high temperature region, the experiment provides stronger light scattering intensities than the theoretical model. Observation of PDLC under a polarized microscope shows that the region in which a liquid crystal is oriented expands with the increase of temperature. We assume from these results that the temperature dependence of the birefringence of a liquid crystal droplet is smaller than that of a bulk liquid crystal, which is mainly caused by the difference of liquid crystal orientation. For applying the SR model to PDLC, we must take into account the temperature dependence of liquid crystal orientation in the droplets.

ELECTRICALLY CONTROLLED CONTINUOUS TILT OF OPTICAL AXIS IN FERROELECTRIC CHIRAL SMECTIC LIQUID CRYSTAL CELL

A continuous tilt of an apparent optical axis caused by an applied ac voltage in a ferroelectric chiral smectic C liquid crystal cell is observed. The cell under crossed Nicols modulates the incident light with the voltage applied between −10 and 10 V. Dispersions of the optical modulation intensity and the dielectric constant have the same relaxation frequency (2 kHz). Observation of the dielectric behavior of the cell suggests that the relaxation in the optical modulation corresponds to that of the Goldstone mode. The deformation of the splay structure in the liquid crystal cell supposedly causes the continuous tilt of apparent optical axis.

Uniformly aligned ferroelectric liquid crystal cell applied to a light valve

Abstract A ferroelectric liquid crystal light valve (FLCLV) for laser pulse recording is studied. We have fabricated a FLCLV that is equipped with a SiO obliquely evaporated film as a liquid crystal alignment layer and a metal-insulator-semiconductor (MIS) photodiode as a photoconductive layer. When the cell gap is about 3um, the liquid crystal alignment shows scale like defects. When the cell gap is reduced to 2um, that scale like defects disappear. High resolution capability of 50 lp/mm is obtained using diode laser, the power of which is merely 20pJ, in this cell.

Edge enhancement recording with ferroelectric liquid crystal spatial light modulator using SiO2/a-Si:H photosensor

Abstract Photo-addressed ferroelectric liquid crystal light modulators (FLC-SLM) are used for optical data processing and display system as binary devices. We have found an edge enhancement effect in our binary FLC-SLM under certain conditions of applied bipolar voltage. We demonstrate this edge enhancement effect in binary FLC-SLM and discuss the origin of this effect.