Atomic force microscope based method of measuring short cholesteric pitch in liquid crystals

Abstract

We present a new, high-resolution method for measuring the helical pitch in cholesteric liquid crystals (CLCs) using an atomic force microscope. This method is based on the measurement of force between a microsphere and a flat surface in the presence of CLCs. The measured force is periodic due to the structural periodicity of the CLC and the pitch can be determined with the accuracy of several nanometres. Besides high accuracy there is no limitation for measuring very short pitches below 200 nm, which is not possible with the standard optical Grandjean–Cano wedge method.

Keywords:

• cholesteric liquid crystal
• pitch measurement
• atomic force microscope

Acknowledgement

We acknowledge the financial support from the 215851-2 EC ITN Marie Curie Research Network Hierarchy.