Abstract: An optical modulation element characterized in that a two-dimensional phase type diffraction gratings, whose refractive index changes for each predetermined period along two different directions in a predetermined plane, is adopted, and a changing state of the refractive index is controlled to change characteristics of the diffraction grating, so that a diffraction phenomenon of light incident on the element is controlled.

Abstract: A liquid crystal optical modulator having a liquid crystal held between two substrates each having a light-transmissive electrode on the surface, in which at least one substrate has minute alignment-treated region having two or more kinds of liquid crystal aligning abilities different from each other formed and arranged on the same substrate.

Abstract: A display element includes a substrate and a display pattern formed on the substrate, the display pattern including a diffraction grating. The width in the direction perpendicular to the grating lines of the diffraction grating of the display pattern is selected so as to prevent re-diffraction of the light diffracted by the one diffraction grating. An observation apparatus includes the afore-said display element, but the display pattern has a first diffraction grating structure and a second diffraction grating structure. An illuminating system and an observation system are added so as to allow for observation of the display pattern. The direction of the grating lines of the first diffraction grating structure differs from that of the grating lines of the second diffraction grating structure, thereby preventing the occurrence of a rainbow-like image.

Abstract: An optical modulation element which enables substantially total transmission of incident light and provides a high contrast when it as used as a display element, thereby enabling multiplex driving.