| 摘要 |
PURPOSE:To obtain the active diffraction grating which can be controlled electrically by making at least one surface of a transparent plate irregular in parallel stripes. CONSTITUTION:On a substrate 1, a transparent electrode 2 is provided and driven by a voltage source 4, but the surface of one of two substrates 1 or the transparent electrode 2 on the substrate 1 is made irregular in periodical stripes to generate a slight difference in panel thickness. An electric field E(x) applied to liquid crystal when a voltage V is applied between the electrodes of the panel because of the slight difference in panel thickness is represented as E(x)=V/d(x). Here, d(x) is the distance between the transparent electrodes and even if the same voltage V is applied according to the irregularity of the panel, the electric field E(x) applied to the liquid crystal is different. When a sufficiently high voltage is applied, the entire surface of the liquid crystal enters a nematic phase, but when the voltage drops, liquid crystal molecules go to parallel to the substrate selectively where the electric field is weak in recessed parts and spiral axes are arrayed in a specific direction to enable diffracted light to be converged on a specific position, so that the diffracted light and transmitted light can be switched with the voltage. |
