A two dimensional diffraction grating incorporating a variable grating mode (VGM) liquid crystal device (LCD)

The variable grating mode (VGM) effect which some nematic liquid crystal materials display is considered. An investigation is described which was initiated by a desire to see if a truly DC effect could be produced and at what orientation the grating 'rolls' could actually be observed. It was possible to produce phase grating patterns both parallel to and perpendicular to the cell alignment direction and, on selected occasions, simultaneously both.<
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