Patent ID: 8213065

Claim:
An image display device comprising: an image forming device including a plurality of pixels arrayed in a two-dimensional matrix manner; a collimating optical system for converting light emitted from the pixels of the image forming device into parallel light; and an optical device which light converted into a plurality of parallel light of which the advancing directions differ by the collimating optical system is input to, and is guided, and is emitted from; wherein said optical device includes a light guide plate wherein input light is propagated internally by total reflection, and is emitted, a first diffraction grating member including a volume hologram diffraction grating for diffracting and reflecting light input to said light guide plate such that light input to said light guide plate is subjected to total reflection within said light guide plate, which is disposed on said light guide plate, and a second diffraction grating member including a volume hologram diffraction grating for diffracting and reflecting light propagated within said light guide plate by total reflection, and emitting the light from said light guide plate, which is disposed on said light guide plate; and wherein when assuming that the center of said first diffraction grating member is the origin, a normal of said first diffraction grating member passing through the origin with the direction toward said collimating optical system side as the positive direction is an X i axis, and the axis line of said light guide plate with the direction passing through the origin, orthogonal to the X i axis, toward said second diffraction grating member side as the positive direction is a Y i axis, central light emitted from the pixel of the center of said image forming device, and passes through the center of the collimating optical system is optically parallel to an X i -Y i plane, and is also intersected with an X i -Z i plane with an acute angle; and wherein the thickness of said second diffraction grating member is thinner than the thickness of said first diffraction grating member.