Transmission type liquid crystal diffraction element, optical element, image display unit, head-mounted display, beam steering, and sensor

Abstract

An object is to provide a liquid crystal diffraction element that has small wavelength dependence of diffraction efficiency and diffracts light having the same wavelength at the same angle, an optical element including the liquid crystal diffraction element, and an image display unit, a head-mounted display, a beam steering, and a sensor including the liquid crystal diffraction element or the optical element. The liquid crystal diffraction element includes an optically-anisotropic layer that includes a liquid crystal compound, in which the optically-anisotropic layer has a liquid crystal alignment pattern in which a direction of an optical axis of the liquid crystal compound continuously rotates in one in-plane direction, and in an image obtained by observing a cross-section of the optically-anisotropic layer with a scanning electron microscope, the optically-anisotropic layer has bright portions and dark portions extending from one surface to another surface, each of the dark portions has two or more inflection points of angle, and the optically-anisotropic layer has regions where tilt directions of the dark portions are different from each other in the thickness direction.