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

摘要

The variable grating mode (VGM) effect which some nematic liquidcrystal materials display is considered. An investigation is describedwhich was initiated by a desire to see if a truly DC effect could beproduced and at what orientation the grating `rolls' could actually beobserved. It was possible to produce phase grating patterns bothparallel to and perpendicular to the cell alignment direction and, onselected occasions, simultaneously both