An Adaptive Microlens Formed by Homeotropic Aligned Liquid Crystal with Positive Dielectric Anisotropy

Abstract

A novel switchable microlens configuration is proposed and demonstrated. An adaptive microlens system was built with a homeotropic aligned liquid crystal of positive dielectric anisotropy and with a circular electrode structure on one side of a sandwiched liquid crystal cell. The fringing effect at the electrode etches produces spatial distribution of the electric field. Applying a voltage deforms the liquid crystal director field. This produces an axially symmetric profile of the extraordinary refractive index. This director configuration is expected to have lens properties. Under the influence of an electric field, the liquid crystal cell becomes a concave (diverging) lens. The director structure was investigated by polarising microscope. We have simulated the director profile with a finite element method and compared the calculated director profile with the measurements. The properties are discussed from the viewpoint of the director orientation in the spatial non-uniform electric field.

Key Words:

• liquid crystal
• homeotropic alignment
• microlens
• optical properties
• polarisation insensitive