ABSTRACT
If we abandon the mirror symmetry present in the ordinary nematics, a new world opens up for applications, for photonics as well as for displays. The basic new phenomenon that now appears is scattering. In practice, we enter this domain by using cholesterics, which is the chiral form of nematics. The nematogenic molecules might themselves be chiral, but we could also, in principle, obtain the cholesteric by adding chiral dopants to the material. If we add dichroic dyes or polymerizable materials to the liquid crystal, we can create highly interesting devices based on either absorption or scattering or both. Cholesteric and nematic devices based on scattering and dichroic effects will be discussed in this entry.
