Study of light distribution through liquid crystal (LC) lens arrays

Abstract

Refractive index gradient formation in liquid crystal cells during the application of an electric field across patterned electrodes was studied. The cells were characterized by measuring the intensity profile of a parallel beam of light passing through the cells. Most of the measurements were performed using transparent electrodes comprising periodic straight-line patterns with a conducting linewidth of 4 μm and various pitches in the range of 34-54 μm. The intensity profiles through such cells were studied and it was observed that the intensity showed oscillations as a function of angle. Director profiles were calculated in order to estimate the effective refractive index distribution within the cells. Using this input in theoretical models based on wave theory as well as geometrical optics, intensity profiles could be estimated. The limits of each theory were illustrated and it was shown that the oscillations in the intensity profile could be explained by the wave theory. The effects of the orientation of the molecules with respect to the electrode lines and cell surfaces and its influence on twist of the molecules leading to depolarization of light were investigated. Various other parameters such as the pitch and the cell thickness on the refractive index gradient formation and the resulting light distribution through the cells were also studied. © 2008 American Institute of Physics.