Deformation of glassy nematic films due to local illumination

We studied photomechanical response of glassy nematic films to a single incident beam of light with circular spot. The effects of some typical director fields including homeotropic, uniaxial, splay-bend and twist distributions were examined. In all these cases, we showed that the mean of spontaneous bending moments in the exposed region arising from light attenuation is nonzero, and the deflection of the film scales logarithmically with the distance from the spot. The phenomenon implies that a local photo-excitation can induce large-scale deformation of glassy nematic films, and the mechanism may be inspiring in various applications of morphology manipulation.