Study Of The Optical Guided Waves In The Vertical Alignment Liquid Crystal Cell

After decades of development, the Liquid Crystal Display Device has almost completely replacedCathode ray tube(CRT)monitors and become the mainstream display device. But there are still manyimperfections, which limit the further development of liquid crystal display, such as low contrast far less thanthe CRT Display and slow response. Vertical Alignment (VA) liquid crystal displays can provide considerablehigh contrast and fast response. So far, the latest Multi-domain Vertical Alignment (MVA)LCD and PatternedVertical Alignment (PVA) LCD technology account for a large share of the LCD TV market, while the VAmode is still hot research in the liquid crystal display field.Optical waveguide is a medium geometric structure which limits the light near the surface or internalguide the direction of light. Although the liquid crystal cell is not designed as an optical waveguide, it is just avery good guided wave structure. The optical properties may be changed greatly as the director make subtlechange in the liquid crystal cell. So we can apply the optical guided wave technology to demonstrate thedirector distribution of liquid crystal in details.Firstly, a prism is used to couple the incident light into the liquid crystal layer and guided modeis achieved. Strong coupling is gained when the momentum of incident polarized light at the prism surfacematches the momentum of guided wave, then note the reflection spectrum of reflected waves with the incidentangle; Secondly, the liquid crystal multi-layer optical theory and the elastic continuum theory are been appliedto make the theory curves consistent with the experimental by adjusting the parameters of liquid crystal and liquid crystal cell. Thus the distribution of liquid crystal director in the cell is achieved.Experimental method described in this article can be used to measure a number of important parametersof liquid crystal and the cell. Meanwhile, we can also verify the feasibility of the experimental method by theprecise parameters obtained in other ways.