Abstract

A Polymer Dispersed Liquid Crystal (PDLC) is a dispersion of liquid crystal microdroplets in a polymeric binder. Droplets are randomly oriented anisotropic spheres and, if their size is close to visible light wavelength, produce a strong light scattering so that the sample is translucent. Light scattering is due to the refractive index mismatch between droplets and surrounding polymer, and can be controlled by changing the droplets effective refractive index: this can be achieved in different manners, but usually it is easily obtained applying an external, low frequency, electric field. Possible applications range from large scale flexible displays to windows with controlled transparency or thermal sensors.In recent papers we have presented detailed experimental and theoretical studies of the behavior of a PDLC sample when a light beam impinges on it. Here we study the frequency dependence of light transmittance in a PDLC sample. To this aim we use a mathematical model assuming the liquid crystal dielectric permittivities ε_|| and ε_⊥ to be the most important parameters for the applied field frequency dependence of light transmittance. Theoretical results show a sudden decrease of the transmitted intensity increasing the frequency of the applied voltage. We present also preliminary experimental results confirming this behavior.

© 1997 Optical Society of America