Using the extended Jones calculus for oblique incidence, we have succeeded in representing light propagation through birefringent media on the Poincaré sphere for arbitrary propagation directions. The situation is far more complicated than for the case of perpendicular transmission. To achieve a simple representation method we had to define appropriate conventions. One can use the method to evaluate the efficiency of existing viewing-angle compensation foils. The Poincaré sphere turns out to be a valid geometrical method for the design of new compensation foils that optimize the contrast ratio. The different parameters of a homogeneous compensation foil that is applied to a liquid-crystal display to improve the viewing-angle properties can be systematically determined.
The measured conoscopic transmission plot of a single Fuji‐Wide View film (1) between crossed polarizers shows an asymmetric character which can not be explained by a twistless uniaxial birefringent compensation structure. Simulations point out the biaxial character of the Fuji‐Wide View film. Furthermore simulations show that the orientation change of the molecules in the discotic layer is rather quadratic instead of linear.
Electrically Controlled Birefringence (ECB) cells are often used to fabricate switchable color filters. The color filter we consider consists of 3 polarizers and 2 birefringent modules. Each module consists of a combination of ECB cells and retardation foils. When a maximum response time is taken into account, one can determine a minimum voltage drop that has to be across the ECB cells. This results in a smaller interval in which the retardation of the cell can vary. Since different colors are achieved by varying the retardations of the two modules, it will be more difficult to obtain a saturated red, green and blue color. In this paper we describe a graphical method to design a fast switching color filter with saturated colors. The method can be used for different kinds of liquid crystal cells.
We extended the representation of light propagation through birefringent media on the Poincaré sphere to the case of oblique incidence. The developed representation was used to design a wide viewing-angle compensation foil for a bi-level TN-LCD.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.