Optical alignment of liquid crystal displays and devices via polarized light

The optical alignment of liquid crystals provides spatial and angular control of the local liquid crystals provides spatial and angular control of the local liquid crystal director. This is achieved by properly designing photosensitive polymer alignment layers. These photosensitive alignment polymers are illuminated with polarized light which alters the bulk and surface properties of the polymer. The liquid crystal molecules adjacent to the alignment polymer interact with the altered polymer and align accordingly. The long range interaction of the liquid crystal molecules transfers the aligned state at the interface to the bulk of the liquid crystal layer. Since the alignment polymer itself is altered, the liquid crystal remains aligned after the illumination is terminated. With the proper design of the alignment material, the process is reversible allowing for the potential of real-time write/re-write control of the local liquid crystal director. In this presentation, we will discuss the use of optical alignment as a non-contact method to align liquid crystal displays. Issues such as the pre-tilt angle and the dielectric properties of the optically controlled alignment polymer will be addressed. Other liquid crystal applications can be realized by combining the high spatial and angular resolution of this process with the birefringent and electro-optical properties of liquid crystals. Novel liquid crystal binary phase and holographic devices, and erasable optical data storage media based on liquid crystals, are possible when reversible optically controlled alignment polymers are used. If time permits, we will review the use of the optical alignment technology for these applications