An analysis of the optical properties of a single-element liquid crystal device

Phase imaging is employed to visualize the optical properties of an electrically controlled birefringent liquid crystal device with particular emphasis being paid to the electrode edges. The apparatus used is a modified Michelson interferometer and the data are manipulated on a personal computer using commercially available software. The phase variation of the element is in principle discontinuous at the electrode edge. However, a phase gradient is observed that is measured to extend beyond the electrode edges by for a directly driven square electrode pattern in a thick device which contains the nematic material E49 approximately 0.75 V above threshold. The phase gradient is discussed in terms of fringing of the electric fields and diffraction at the phase boundary in the element.