Characteristics of the Freedericksz effect specific to optical fields

Features of the optical Freedericksz effect, which do not appear in static fields, are identified. It is shown that in the case of oblique incidence of light relative to the detector we can expect the threshold-free effect when an ordinary wave is incident on a cell with a nematic (this effect is due to the appearance of an extraordinary component in the scattering of light by fluctuations of the director) as well as the threshold effect in the field of an extraordinary wave (this effect is due to adiabatic propagation of light).