Index of content:
Volume 86, Issue 11, 01 December 1999
- LASERS, OPTICS, AND OPTOELECTRONICS (PACS 42)
Reversible optical control of transmittance in polymer/liquid crystal composite films by photoinduced phase transition86(1999); http://dx.doi.org/10.1063/1.371717View Description Hide Description
We have demonstrated reversible change in transmittance of compositefilms, which are composed of an isotropic (I) polymer matrix and a host nematic (N) liquid crystal(LC) containing donor–acceptor type azobenzene LCs (AzoLCs) as photoresponsive molecules, by means of reversible phase transition in the LC domain. The compositefilms were prepared by in situ thermal polymerization-induced phase separation (PIPS) method from their homogeneous mixtures. Photoisomerization of AzoLCs was induced within the polymer network, and the resultant effect brought about isothermal change in transmittance. The photoinduced reversible and repeatable changes between opaque light scattering and clear transparent states were achieved effectively by irradiation with a monochromatic light at 366 nm. These changes are attributed to photochemical phase transition and rapid thermal phase transition in the host LC domain based on reversible change in molecular sharp of the guest AzoLCs. The optical effects were influenced by such factors as temperature of the compositefilms in the initial state and photoisomerization ability of the guest AzoLCs. The compositefilms acted as an optical switching material without polarizers.
86(1999); http://dx.doi.org/10.1063/1.371636View Description Hide Description
We have developed a dynamic parameter space method to represent the operation modes of general twisted nematicliquid crystal displays. This method was based on the efficient calculation programs for director distributions by variation technique and optical properties by Berreman’s 4×4 matrix technique. Transmission or reflectance of liquid crystal displaydevices could be calculated in space with varying voltage applied. The dynamic parameter space method is a useful tool to optimize the operation modes of liquid crystal displays.