Light guide element, image display device, and sensing apparatus

A light guide element comprising:

• a light guide plate;
• and
• a first diffraction element, a second diffraction element, and a third diffraction element that are provided on the light guide plate,
• wherein the first diffraction element diffracts incident light in two or more different directions to be incident into the light guide plate,
• the second diffraction element includes a plurality of diffraction elements that are provided to be spaced from each other in a plane direction of the light guide plate and diffract the light diffracted by the first diffraction element and propagated in the light guide plate to the third diffraction element,
• the third diffraction element emits the light from the light guide plate,
• at least one of the first diffraction element or the third diffraction element is a liquid crystal diffraction element that is formed of a composition including a liquid crystal compound and 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 first diffraction element includes a first A diffraction element and a first B diffraction element that are laminated and diffract light in different directions,
• the first diffraction element is the liquid crystal diffraction element,
• the first A diffraction element and the first B diffraction element each have a region where the direction of the optical axis of the liquid crystal compound is helically twisted in a thickness direction and rotates, and
• in the first A diffraction element and the first B diffraction element, directions of the helical twist rotation in the thickness direction are opposite to each other and rotation directions of the direction of the optical axis derived from the liquid crystal compound that continuously rotates in the at least one in-plane direction in the liquid crystal alignment pattern are the same.

A light guide element comprising:

• a light guide plate;
• and
• a first diffraction element, a second diffraction element, and a third diffraction element that are provided on the light guide plate,
• wherein the first diffraction element diffracts incident light in two or more different directions to be incident into the light guide plate,
• the second diffraction element includes a plurality of diffraction elements that are provided to be spaced from each other in a plane direction of the light guide plate and diffract the light diffracted by the first diffraction element and propagated in the light guide plate to the third diffraction element,
• the third diffraction element emits the light from the light guide plate,
• at least one of the first diffraction element or the third diffraction element is a liquid crystal diffraction element that is formed of a composition including a liquid crystal compound and 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 first diffraction element includes a first A diffraction element and a first B diffraction element that are laminated and diffract light in different directions,
• the first diffraction element is the liquid crystal diffraction element,
• the first A diffraction element and the first B diffraction element have a region where the direction of the optical axis of the liquid crystal compound is helically twisted in a thickness direction and rotates, and
• in the first A diffraction element and the first B diffraction element, directions of the helical twist rotation in the thickness direction are the same and rotation directions of the direction of the optical axis derived from the liquid crystal compound that continuously rotates in the at least one in-plane direction in the liquid crystal alignment pattern are different from each other.