Nonlinear deformation topography of glassy nematic films under local illumination

Azobenzene-containing nematic glasses have an attractive application perspective in photo-driven deformation devices due to their unique photo-responsive properties. Based on the Fppl-von Kármán plate theory and a kinetics method, a numerical approach was developed to predict the nonlinear deformation topography of glassy nematic films under local illumination, and detailed results were given for two typical director fields of splay-bend and twist distributions when the spot of incident light is a circle. It is found that when the ratio of spot radius to film thickness is increased to a certain critical value, dramatic variation of the topography of the exposed part of the film occurs, accompanying the transition of Gauss curvature from positive to negative. This phenomenon is attributed to the spontaneous bending moments induced by attenuation of light intensity across film thickness, and may be applied to design new types of deformation devices with contactless control.