Liquid crystal optically variable device with continuously distributed colors

A liquid crystal optically variable device (LCOVD) was fabricated by linearly polarized photoalignment technique. The device is composed of a nematic liquid crystal layer on the polyethylene terephthalate (PET) substrate and two parallel polarizers. By continuously changing the polarization direction during photoalignment, the optical axes of the liquid crystal can be variably aligned. We measured the colors and transmission spectra of the LCOVD at different observing angles. The results indicate that the colors of the device distribute continuously. The colors shift to others with the changing of the observing positions, and such color shift phenomenon depends not only on the observing inclination angle but also the azimuth angle. Furthermore, a calculation method based on the Jones matrix for simulating the performance of the LCOVD was established. The theoretical results show good agreement with the experiment. Because of the distinctive optical features, one highly significant application of the LCOVD may be its use for improving document security.