Anisotropic films, transmittance

Transmittance of the anisotropic films is usually studied by placing the film between crossed polarizers. Polarizers are uniaxially anisotropic in their absorption, i.e., the complex refractive indices are different, so that ... 

For instance, for a nematic polymer with positive anisotropy of dielectric constant (Ae > 0) orientation of mesogenic groups along the applied field takes place (homeo-tropic orientation). The fact of orientation is illustrated in Fig. 25, which shows that under crossed polarizers the optical transmittance I of a film of nematic polymer with optically anisotropic texture (taken for 100%) falls practically to zero when a low-frequency field is switched on. 

A very simple linear approximation for the transmittance of an anisotropic thin film deposited on a transparent isotropic substrate has been reported by Buffeteau et al. [128] ... 

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