Patent ID: 7835050

Claim:
An image display device, comprising: a display element for displaying an image; and an ocular optical system for conducting image light from the display element to an observer's pupil, wherein the ocular optical system includes, along a single optical path from the display element to the observer's pupil, a substrate having a first surface, a normal of the first surface being inclined relative to an optical axis of the image display device, and a volume phase type hologram optical element formed on the first surface of the substrate for diffracting and reflecting incident light, wherein: the hologram optical element is formed in an area that is smaller than an irradiation area on the first surface of the substrate that, in operation, is irradiated with light, the hologram optical element is larger in a first direction along the first surface of the substrate than in a second direction along the first surface of the substrate, and the first direction is a direction perpendicular to a plane that includes the optical axis of light incident on the hologram optical element and the optical axis of light reflected from the hologram optical element, and the second direction is a direction perpendicular to the first direction.