On The Fringing-field Effect Of LCOS Panels For Holographic Display

With the rapid development of electronic, optical and material, a demand for information representation becomes higher and higher. The convenience and speed are required, at the same time people also have higher requirement in its3D perception and comfort aspects. Holography display is the ultimate3D visualization tool that can provide both the amplitude and phase of a object wave, meeting the physiology and psychology of human visual factors.Gabor introduced optical holography, which used high-resolution plate or film as the display medium. Although this technology could achieve a true three-dimensional visual impression, not realize the demand for dynamic, real-time display. In1994, MIT Media Lab used acousto-optic modulator to achieve dynamic three-dimensional holographic display system, bringing holographic from film age to digital age. Spatial light modulator, which can dynamic modulate incident light in real time, is the core device of holographic display. Liquid crystal on silicon (LCOS), one of the liquid crystal spatial light modulator, has many advantages, such as high fill factor and high resolution. LCOS is considered to be the ideal tool to realize holographic display. The main work of this thesis is summarized as follows:1) The reasons that the holographic video display has currently not been available is that the pitch of the pixel of the available spatial light modulator made by Liquid crystal can not provide a sufficiently wide angle of field. In order to show a useful hologram for useful3-D perception, both the viewer’s eyes have to fit into the view zone, and ideally the viewer can move around a bit and see even more of the scene. However, the diffraction angle offered by current LCOS device is not enough; in order to increase the angle the pixel size must be reduced. When the pixel size becomes small, the fringing field effects between adjacent pixels caused by directors among liquid crystal molecule under the electric field are produced, resulting in a serious negative impact on the depth of the phase modulation and diffraction efficiency.2) Based on Gibbs free energy theory, a mathematical model to solve the distribution of liquid crystal directors is built. Using the difference iterative method can obtain the distribution of liquid crystal director. The distribution of liquid crystal director determines the modulation effect of LCOS on beam. The work described above forms the foundation for further quantitative analysis of diffraction characteristics and the fringing field effects of LCOS.3) The fringing field effect of the high resolution LCOS is explained, the ratio of the pixel electrode width and thickness of liquid crystal cell thickness is smaller, the fringing effect of the field between adjacent pixels is stronger. Three kinds of liquid crystal devices of different electrode structure are analyzed and simulated, as the result the bilateral interdigital electrode structure is proved that it can effectively suppress the fringing field effect and provide a better solution method for holographic video display based on spatial light modulator.