| 摘要 |
PURPOSE:To prevent defective orientation by the deformation of a diffraction grating and an increase of electric current consumption, etc., and to improve reliability by forming a protective film essentially consisting of an inorg. oxide on the surface of the diffraction grating in contact with a liquid crystal. CONSTITUTION:Optical modulation is executed by packing the liquid crystal 1 between two substrates, at least one of which has diffraction grating structure, and changing the refractive index of the liquid crystal 1. The protective film contg. the inorg. oxide as the component is provided on at least the surface of the diffraction grating 2 in contact with the liquid crystal 1. The protective film is set preferably in a 50-2,000Angstrom range. Pinholes are generated if the film is thinner than said range. Cracks are generated and the reliability of the protective film is low if the film is thicker than said range. The diffraction grating constitution is adequately set in the above-mentioned manner at the time of making optical modulation such as passage and shielding of light by utilizing the refractive index variable material such as liquid crystal 1 and the diffraction grating 2, by which the always good optical modulation is executed and the reliability is improved. The elution of the material constituting the diffraction grating in the liquid crystal and the moisture in the liquid crystal is prevented. |
