Placing liquid crystals between two surfaces that are smooth grooves. Smooth grooves on the surface make an angle of 90o a (perpendicular) with smooth grooves on another surface. If the molecules are arranged on one surface from north to south and one molecule on the other surface leads from west to east, there are molecules of which will be forced to rotate 90o. As a result, the path of light that followed the structure of this molecule also rotates 90 ° when passing through the liquid crystal. When electricity stress supplied to the liquid crystal, molecules will arrange themselves vertically lets light to pass through without turning 90o.
b. Rely on the polarization properties (is a collection of very fine parallel lines). Through this polarizing filter, the light from background sources is filtered and then rotated by the liquid crystals and is filtered again before exciting