Transmissive liquid crystal diffraction element

Abstract

Provided is a transmissive liquid crystal diffraction element having a large diffraction angle and a high diffraction efficiency. The transmissive liquid crystal diffraction element includes a plurality of optically-anisotropic layers that are formed of a liquid crystal composition including a liquid crystal compound in a thickness direction, in which the optically-anisotropic layer has a liquid crystal alignment pattern in which a direction of an optical axis derived from the liquid crystal compound changes while continuously rotating in at least one in-plane direction, the one in-plane directions of the plurality of optically-anisotropic layers are parallel to each other, in two optically-anisotropic layers adjacent to each other among the plurality of optically-anisotropic layers, a rotation direction of the optical axis in the liquid crystal alignment pattern of one optically-anisotropic layer and a rotation direction of the optical axis in the liquid crystal alignment pattern of the other optically-anisotropic layer are opposite to each other, in cross-sectional images of the plurality of optically-anisotropic layers obtained by observing cross-sections taken in a thickness direction parallel to the one in-plane direction with a scanning electron microscope, the plurality of optically-anisotropic layers have bright portions and dark portions extending from one surface to another surface, and tilt angles of the dark portions of the plurality of optically-anisotropic layers change in order in the thickness direction.