An optical phase control device using a liquid crystal (LC) material without an applied voltage has been reported [1]. The director of LC molecules in the LC cell partly aligns parallel and perpendicular directions to the substrate, where a patterned alignment film is constructed by a photolithography technique on another alignment film. The optical phase can be controlled by the pattern density of the alignment film. In this paper, we demonstrate a possibility of a new type of LC optical device using the patterned alignment film. Circle patterns with small diameter size (about 1 micron) of the photo-resist film at random positions are fabricated on the alignment film by using a photolithography method. The pattern density was given the gradation with many steps from 0 to 100 %. The optical phase retardation of a transmission light through the LC cell with the patterned alignment film was measured with and without the applied voltage. In the case of no applied voltage, it was observed that change of the optical phase corresponded to the pattern density of the alignment film. It is indicated that the change of the LC molecular alignment appears with a gradation of the pattern density on the alignment film. This LC molecular distribution state seems to function as a two-dimensional optical retardation device. The optical retardation decreases as increasing the voltage. These experimental results show that the optical device with two-dimensional optical phase distribution such as an optical lens can be achieved by the LC cell using the patterned alignment film without the applied voltage.

[1] S. Yanase, M. Kawamura, R. Yamaguchi, T. Takahashi and S. Sato: Proc. of SPIE, 5936, 593614-1 (2005.8).