Chiral nematic droplets with parallel surface anchoring

Abstract

Chiral nematic droplets of various radii $R$ and intrinsic pitch $P$ with parallel boundary conditions have been observed using a polarizing microscope. The visual appearances of the droplets have been compared with computer simulations from model director fields. It is found that the director configuration depends strongly on the ratio $R/P.\mathrm{}$ For $P>R,$ the droplets have a twisted bipolar structure. For $P<R,$ the director field takes on the Frank-Pryce structure. For $P\ll R,$ the droplet appearance is similar to that of a radial nematic drop, but the director field is still described by the Frank-Pryce model. We present a phase stability diagram for the two structures, and show how the structural transition between them proceeds continuously through intermediate states.