title: Diffraction from a liquid crystal phase grating.
abstract: The diffraction of light by a sinusoidal perturbation of the optic axis in a nematic liquid crystal is discussed. This corresponds to experiments at the electrohydrodynamic instability thresholds. An interesting qualitative feature appears: The diffraction pattern exhibits a contribution at half of the expected spatial frequency, corresponding to nonorthogonal traversals of the thick phase grating.
authors.forename: R A
authors.initials: RA
authors.lastname: Kashnow
authors.forename: J E
authors.initials: JE
authors.lastname: Bigelow