Transmission type laminated hologram optical element and image display device comprising this optical element

An image display apparatus comprising:

• an illumination light source for emitting illumination light;
• a transmission type laminated hologram optical element for diffracting incident light;
• an illumination optical system for guiding the illumination light to the transmission type laminated hologram optical element as incident light;
• a spatial light modulation element for modulating illumination light which has been emitted from the transmission type laminated hologram optical element;
• and
• a magnification optical system for magnifying the illumination light which has been modulated by the spatial light modulation element to form an image thereof,
• wherein the transmission type laminated hologram optical element is caused to be of the configuration such that a plurality of transmission type hologram optical elements in which diffraction acceptance incident angles are different from each other, and outgoing angles with respect to center incident angles of respective diffraction acceptance incident angles at an arbitrary wavelength of the visible region are different from each other are laminated.

An image display apparatus comprising:

• an illumination light source for emitting illumination light;
• a transmission type polarization selective hologram optical element having a structure in that two regions where incident polarization azimuth dependencies of a refractive index are different from each other are arranged in order, and caused to be of the configuration such that a plurality of transmission type hologram optical elements in which diffraction acceptance incident angles are different from each other are laminated to diffract incident light;
• an illumination optical system for guiding the illumination light to allow it to be incident on the transmission type polarization selective hologram optical element at an incident angle from more than 30° to less than 90° with respect to a normal of the illumination light receiving surface of the transmission type polarization selective hologram optical element;
• a reflection type spatial light modulation element for modulating a polarization state of illumination light which has been diffracted by the transmission type polarization selective hologram optical element;
• and
• a magnification optical system for magnifying a display image which has been modulated by the reflection type spatial light modulation element,
• wherein respective transmission type hologram optical elements constituting the transmission type polarization selective hologram optical element are adapted so that outgoing angles with respect to center incident angles of respective diffraction acceptance incident angles at an arbitrary wavelength of the visible region are different from each other, and serves to diffract a P-polarized light component or an S-polarized light component of illumination light to be received mainly toward the reflection type spatial modulation element and to allow diffraction efficiency with respect to a polarization component perpendicular to a polarization component which is mainly diffracted at the first incidence of rays of illumination light which are re-incident after having undergone a phase modulation by the reflection type spatial light modulation element to be 10% or less so that 70% of the component or more is transmitted.