An overview is given of the methods for preparation of birefringent films with patterned optical properties and their applications in liquid crystal displays. A versatile method of obtaining patterned films is based on manipulation of the helical twisting power of chiral dopants by photoisomerization reactions. Because of their transparency to visible light, high helical twisting power and large changes of the helical twisting power during UV irradiation, menthone derivatives are very suitable dopants for this process. A number of potential applications of the principles are discussed. Patterning of chiral nematic films with regions with different twisting angles is a suitable method for the preparation of patterned polarization rotators. Patterning of chiral nematic liquid crystal layers can also be used to control the reflection color and state of polarization of the reflected light. Such layers are useful for the preparation of reflective color filter arrays and broad band reflective polarizers.
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