Grandjean cholesteric helix

Fig. 4.28 A wedge type cell filled with a cholesteric (a) with Grandjean zones marked by numbers 0, 1, 2, 3, 4. .. and the disclination lines shown by arrows. The distance dependence of the helix pitch in different zones with numbers m is schematically shown in sketch (b). Photo of disclinations limiting the Grandjean zones (c)...

Cholesteric phases can also be ordered between glass plates. By the application of a small pressure a so called layered or Grandjean texture is obtained in this texture the nematic layers of the cholesteric phase orient parallel to the surface, that is the helix (or optic) axis points in a direction normal to the glass surface. 

The second related example is the planar or Grandjean texture of the cholesteric mesophase. In the planar state, the main helix axis is perpendicular to the electrode surfaces of the cell. Consequently, the director is always oriented parallel to the surface with the orientation... 

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