Hologram optical element, fabrication method thereof, and image display apparatus

An image display apparatus comprising:

• a display device displaying an image;
• and
• an enlargement optical system presenting a viewer with an enlarged virtual image of the image displayed by the display device,
• wherein
• the enlargement optical system has a volume-phase reflection hologram optical element diffraction-reflecting image light from the display device to direct the image light to the viewer's pupil, and
• when
• an axis optically connecting between a center of a display area of the display device and a center of an optical pupil formed by the enlargement optical system is called an optical axis,
• two directions mutually perpendicular and perpendicular to the optical axis are called a first direction and a second direction respectively,
• a plane parallel to the optical axis and including the first direction at a position of the optical pupil is called a first plane, and
• a plane parallel to the optical axis and including the second direction at a position of the optical pupil is called a second plane, then
• a component of a predetermined wavelength of the image light diffraction-reflected by the hologram optical element is focused at positions different in an optical axis direction between on the first plane and on the second plane.