Image display element, and image display device
First Claim
1. An image display device comprising:
- a polarization selective holographic optical device for diffracting illuminating light, said device including a plurality of each of two areas having refractive index values exhibiting respectively different incidence polarization orientation dependencies, said areas being layered sequentially alternately; and
a reflection type spatial optical modulator for modulating the state of polarization of the illuminating light diffracted by said polarization selective holographic optical device;
said polarization selective holographic optical device, one of two areas of which exhibits refractive index anisotropy, with the other exhibiting refractive index isotropy, being irradiated with the illuminating light at an angle of incidence not less than 30° and
less than 90°
with respect to a normal line to a light receiving surface thereof for said illuminating light, said polarization selective holographic optical device diffracting a P-polarized light component or an S-polarized light component of said illuminating light to radiate the diffracted light towards said reflection type spatial optical modulator;
said polarization selective holographic optical device exhibiting the diffraction efficiency of not higher than 10% for the polarized light component of the illuminating light incident a second time thereon after phase modulation by said reflection type spatial optical modulator, which polarized light component has a direction of polarization perpendicular to a direction of polarization of the polarized light component diffracted thereby at the time when the illuminating light is first incident thereon, whereby not less than 70% of the diffracted polarized light component is transmitted through the optical device.
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Abstract
An image display device including a polarization selective holographic optical device for diffracting illuminating light, and a reflection type spatial optical modulator for modulating the state of polarization of the illuminating light diffracted by the polarization selective holographic optical device is disclosed. The device includes a plurality of each of two areas of respectively different incidence polarization orientation dependencies of the refractive index, with the layers being layered sequentially alternately. An image display apparatus including the above image display device, a light source, an illuminating optical system and a projection optical system is also disclosed. With the present optical display device and optical display apparatus, the utilization efficiency of the illuminating light may be improved, while the device and the apparatus may be reduced in size and production cost, as uniformity and high contrast of the image displayed are achieved simultaneously.
48 Citations
94 Claims
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1. An image display device comprising:
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a polarization selective holographic optical device for diffracting illuminating light, said device including a plurality of each of two areas having refractive index values exhibiting respectively different incidence polarization orientation dependencies, said areas being layered sequentially alternately; and
a reflection type spatial optical modulator for modulating the state of polarization of the illuminating light diffracted by said polarization selective holographic optical device;
said polarization selective holographic optical device, one of two areas of which exhibits refractive index anisotropy, with the other exhibiting refractive index isotropy, being irradiated with the illuminating light at an angle of incidence not less than 30° and
less than 90°
with respect to a normal line to a light receiving surface thereof for said illuminating light, said polarization selective holographic optical device diffracting a P-polarized light component or an S-polarized light component of said illuminating light to radiate the diffracted light towards said reflection type spatial optical modulator;
said polarization selective holographic optical device exhibiting the diffraction efficiency of not higher than 10% for the polarized light component of the illuminating light incident a second time thereon after phase modulation by said reflection type spatial optical modulator, which polarized light component has a direction of polarization perpendicular to a direction of polarization of the polarized light component diffracted thereby at the time when the illuminating light is first incident thereon, whereby not less than 70% of the diffracted polarized light component is transmitted through the optical device.- View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13)
said polarization selective holographic optical device having a lens action of separating the incident illuminating light from one wavelength range to another and of converging the separated light wavelength portions on associated color pixels of the reflection type spatial optical modulator.
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13. The image display device according to claim 1 further comprising:
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a first prism for being irradiated with the diffracted light and with the non-diffracted light through the polarization selective holographic optical device and for subjecting at least one of the incident diffracted light and the incident non-diffracted light to internal total reflection at least once to cause the light thus totally reflected to be radiated from an outgoing surface; and
a second prism;
said reflection type spatial optical modulator being irradiated with the light radiated from said first prism and diffracted by said polarization selective holographic optical device;
said second prism having at least one apex angle approximately equal to one of the apex angles of said first prism;
the light incident surface of said first prism of the light diffracted by said polarization selective holographic optical device being approximately parallel to an outgoing surface of said second prism for said diffracted light incident through said first prism on said second prism to exit said second prism.
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14. An image display apparatus comprising:
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a light source for radiating illuminating light;
a polarization selective holographic optical device for diffracting illuminating light, said device including a plurality of each of two areas having refractive index values exhibiting respectively different incidence polarization orientation dependencies, said areas being layered sequentially alternately;
an illuminating optical system for causing the illuminating light radiated from said light source to be incident on said polarization selective holographic optical device;
a reflection type spatial optical modulator for modulating the polarized state of the illuminating light diffracted by said polarization selective holographic optical device; and
a projection optical system for projecting the illuminating light on a screen through said reflection type spatial optical modulator and through said polarization selective holographic optical device;
said polarization selective holographic optical device, one of two areas of which exhibits refractive index anisotropy, with the other exhibiting refractive index isotropy, being irradiated by said illuminating optical system with the illuminating light at an angle of incidence not less than 30° and
less than 90°
with respect to a normal line to a light receiving surface thereof for said illuminating light, said polarization selective holographic optical device diffracting a P-polarized light component or an S-polarized light component of said illuminating light to radiate the diffracted light towards said reflection type spatial optical modulator;
said polarization selective holographic optical device exhibiting the diffraction efficiency of not higher than 10% for the polarized light component of the illuminating light incident a second time thereon after phase modulation by said reflection type spatial optical modulator, which polarized light component has a direction of polarization perpendicular to a direction of polarization of the polarized light component diffracted thereby at the time when the illuminating light is first incident thereon, whereby not less than 70% of the diffracted polarized light component is transmitted through the optical device;
said projection optical system projecting the light transmitted through said polarization selective holographic optical device on a screen. - View Dependent Claims (15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36)
the light source or the illuminating optical system includes time-sequential wavelength range switching means for temporally sequentially transmitting only a plurality of specified wavelength ranges of the total wavelength range of the illuminating light. -
20. The image display apparatus according to claim 14 wherein
the illuminating optical system has a polarization selective holographic optical device for correction having a bend angle opposite in sign to the bend angle of the polarization selective holographic optical device. -
21. The image display apparatus according to claim 20 wherein
the polarization selective holographic optical device for correction is the same type device as the polarization selective holographic optical device. -
22. The image display apparatus according to claim 14 further comprising:
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a coupling prism optically tightly bonded to the polarization selective holographic optical device and having at least a first optical surface irradiated with the illuminating light substantially perpendicularly and a second optical surface from which the light reflected by said reflection type spatial optical modulator is radiated substantially perpendicularly;
said illuminating light being incident on a light receiving surface of said polarization selective holographic optical device at an angle of incidence not less than 60° and
less than 90°
relative to a line normal to the illuminating light receiving surface.
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23. The image display apparatus according to claim 22 wherein the coupling prism has a third optical surface including a light absorbing layer irradiated substantially perpendicularly with the regular reflected light of the illuminating light by said reflection type spatial optical modulator.
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24. The image display apparatus according to claim 14 wherein the projection optical system includes polarization selection means for selectively transmitting a component of the orientation of polarization of the modulated light by said reflection type spatial optical modulator which is transmitted through said polarization selective holographic optical device.
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25. The image display a apparatus according to claim 14 wherein said polarization selective holographic optical device permits the illuminating light as the P-polarized light to be incident thereon.
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26. The image display apparatus according to claim 14 wherein the bend angle of the polarization selective holographic optical device is not less than 30°
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27. The image display apparatus according to claim 14 wherein the hologram surface of the polarization selective holographic optical device and the reflecting surface of the reflection type spatial optical modulator exhibit optically non-parallel position relationships to each other.
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28. The image display apparatus according to claim 14 wherein the polarization selective holographic optical device is made up of a plurality of hologram layers having respective different wavelength dependencies of the diffraction efficiency.
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29. The image display apparatus according to claim 14 wherein the polarization selective holographic optical device is made up of a plurality of hologram layers having respective different reproducing light incidence angle dependencies of the diffraction efficiency.
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30. The image display apparatus according to claim 14 wherein the polarization selective holographic optical device comprises a plurality of holograms exhibiting respective different wavelength dependencies of the diffraction efficiency, said hologram layers being multiplexed in one hologram layer.
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31. The image display apparatus according to claim 14 wherein the polarization selective holographic optical device comprises a plurality of holograms of respective different reproducing light incidence angle dependencies of the diffraction efficiency multiplexed in one hologram layer.
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32. The image display apparatus according to claim 14 wherein
the polarization selective holographic optical device is formed of a liquid crystal material. -
33. The image display apparatus according to claim 14 wherein
the polarization selective holographic optical device and the reflection type spatial optical modulator are optically tightly bonded and unified together. -
34. The image display apparatus according to claim 14 wherein
the reflection type spatial optical modulator has a rectangular profile with the long side direction of the rectangle coinciding with the direction of incidence of the illuminating light to the polarization selective holographic optical device. -
35. The image display apparatus according to claim 14 wherein the reflection type spatial optical modulator includes a plurality of color pixels;
said polarization selective holographic optical device having a lens action of separating the incident illuminating light from one wavelength range to another and of converging the separated light portions on associated color pixels of the reflection type spatial optical modulator.
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36. The image display apparatus according to claim 14 further comprising:
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a first prism for being irradiated with the diffracted light and with the non-diffracted light through the polarization selective holographic optical device and for subjecting at least one of the incident diffracted light and the incident non-diffracted light to internal total reflection at least once to cause the light thus totally reflected to be radiated from an outgoing surface; and
a second prism;
said reflection type spatial optical modulator being irradiated with the light radiated through said first prism and diffracted by said polarization selective holographic optical device;
said second prism having at least one apex angle approximately equal to one of the apex angles of said first prism;
the light incident surface of said first prism for the light diffracted by said polarization selective holographic optical device being approximately parallel to an outgoing surface of said second prism for said diffracted light incident through said first prism on said second prism to exit said second prism.
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37. An image display apparatus comprising:
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a polarization selective holographic optical device for diffracting the incident light, said device including a plurality of each of two areas having refractive index values exhibiting respectively different incidence polarization orientation dependencies, said areas being layered sequentially alternately;
color separation means for separating said illuminating light in a plurality of representing different wavelength range components;
an illuminating optical system for causing the illuminating light separated into respective different wavelength range components to be incident on said polarization selective holographic optical device;
a plurality of reflection type spatial optical modulators for modulating polarized states of a plurality of representing different wavelength range components of the illuminating light diffracted by said polarization selective holographic optical device;
color synthesis means for synthesizing illuminating light portions of respective different wavelength ranges modulated by said plural reflection type spatial optical modulators; and
a projection optical system for projecting the illuminating light through said color synthesis means;
wherein said polarization selective holographic optical device, one of two areas of which exhibits refractive index anisotropy, with the other exhibiting refractive index isotropy, being irradiated by said illuminating optical system with the illuminating light at an angle of incidence not less than 30° and
less than 90°
with respect to a normal line to a light receiving surface thereof for said illuminating light, said polarization selective holographic optical device diffracting a P-polarized light component or an S-polarized light component of said illuminating light to radiate the diffracted light towards said reflection type spatial optical modulators;
said polarization selective holographic optical device exhibiting the diffraction efficiency of not higher than 10% for the polarized light component of the illuminating light incident a second time thereon after phase modulation by said reflection type spatial optical modulators, which polarized light component has a direction of polarization perpendicular to a direction of polarization of the polarized light component diffracted thereby at the time when the illuminating light is first incident thereon, whereby not less than 70% of the diffracted polarized light component is transmitted through the optical device;
said projection optical system projecting the illuminating light transmitted through said polarization selective holographic optical device and through said color synthesis means on a screen. - View Dependent Claims (38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, 52, 53, 54, 55, 56, 57)
the reflection type spatial optical modulator has a rectangular profile with the long side direction of the rectangle coinciding with the direction of incidence of the illuminating light to the polarization selective holographic optical device. -
40. The image display apparatus according to claim 37 wherein
said color separation means and said color synthesis means use a cross-dichroic mirror in common. -
41. The image display apparatus according to claim 37 wherein said illuminating optical system includes polarization transforming means of effecting rotation through 90°
- of the orientation of polarization of a component of the illuminating light having an orientation of polarization perpendicular to the orientation of polarization for which the diffraction efficiency of the polarization selective holographic optical device is maximum.
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42. The image display apparatus according to claim 37 wherein said illuminating optical system includes polarization selection means for selectively transmitting a component of the illuminating light having an orientation of polarization for which the diffraction efficiency of the polarization selective holographic optical device is maximum.
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43. The image display apparatus according to claim 37 wherein the light source or the illuminating optical system includes time-sequential wavelength range switching means for temporally sequentially transmitting only a plurality of specified wavelength ranges of the total wavelength range of the illuminating light.
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44. The image display apparatus according to claim 37 wherein
the illuminating optical system has a polarization selective holographic optical device for correction having a bend angle opposite in sign to the bend angle of the polarization selective holographic optical device. -
45. The image display apparatus according to claim 44 wherein
the polarization selective holographic optical device for correction is the same type device as the polarization selective holographic optical device. -
46. The image display apparatus according to claim 37 further comprising:
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a coupling prism optically tightly bonded to the polarization selective holographic optical device and having at least a first optical surface irradiated with the illuminating light substantially perpendicularly and a second optical surface from which the light reflected by said reflection type spatial optical modulator is radiated substantially perpendicularly;
said illuminating light being incident on a light receiving surface of said polarization selective holographic optical device at an angle of incidence not less than 60° and
less than 90°
.
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47. The image display apparatus according to claim 46 wherein the coupling prism has a third optical surface including a light absorbing layer irradiated substantially perpendicularly with the regular reflected light of the illuminating light by said reflection type spatial optical modulator.
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48. The image display apparatus according to claim 37 wherein the projection optical system includes polarization selection means for selectively transmitting a component of the orientation of polarization of the light modulated by said reflection type spatial optical modulator which is transmitted through said polarization selective holographic optical device.
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49. The image display apparatus according to claim 37 wherein said polarization selective holographic optical device permits the illuminating light as the P-polarized light to be incident thereon.
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50. The image display apparatus according to claim 37 wherein the bend angle of the polarization selective holographic optical device is not less than 30°
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51. The image display apparatus according to claim 37 wherein the hologram surface of the polarization selective holographic optical device and the reflecting surface of the reflection type spatial optical modulator exhibit optically non-parallel position relationships to each other.
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52. The image display apparatus according to claim 37 wherein the polarization selective holographic optical device is made up of a plurality of hologram layers having respective different wavelength dependencies of the diffraction efficiency.
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53. The image display apparatus according to claim 37 wherein the polarization selective holographic optical device is made up of a plurality of hologram layers having respective different reproducing light incidence angle dependencies of the diffraction efficiency.
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54. The image display apparatus according to claim 37 wherein the polarization selective holographic optical device comprises a plurality of holograms of respective different wavelength dependencies of the diffraction efficiency multiplexed in one hologram layer.
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55. The image display apparatus according to claim 37 wherein the polarization selective holographic optical device comprises a plurality of holograms of respective different reproducing light incidence angle dependencies of the diffraction efficiency multiplexed in one hologram layer.
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56. The image display apparatus according to claim 37 wherein
the polarization selective holographic optical device is formed of a liquid crystal material. -
57. The image display apparatus according to claim 37 wherein
the reflection type spatial optical modulator has a rectangular profile with the long side direction of the rectangle coinciding with the direction of incidence of the illuminating light to the polarization selective holographic optical device.
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58. An image display apparatus comprising:
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a light source for radiating illuminating light;
a polarization selective holographic optical device for diffracting illuminating light, said device including a plurality of each of two areas having refractive index values exhibiting respectively different incidence polarization orientation dependencies, said areas being layered sequentially alternately;
wavelength-band-based polarization separating means for separating the states of polarization of respective different first and second wavelength range components of said illuminating light as linear polarized components perpendicular to each other;
an illuminating optical system for causing the illuminating light separated into first and second wavelength range components to be incident on said polarization selective holographic optical device;
a first reflection type spatial optical modulator for modulating the state of polarization of the first wavelength range component of the illuminating light diffracted by the polarization selective holographic optical device;
a second reflection type spatial optical modulator for modulating the state of polarization of the second wavelength range component of the illuminating light transmitted through the polarization selective holographic optical device; and
a projection optical system for projecting the illuminating light through said reflection type spatial optical modulator on a screen;
said polarization selective holographic optical device, one of two areas of which exhibits refractive index anisotropy, with the other exhibiting refractive index isotropy, being irradiated by said illuminating optical system with the illuminating light at an angle of incidence not less than 30° and
less than 90°
with respect to a normal line to a light receiving surface thereof for said illuminating light, said polarization selective holographic optical device diffracting said first wavelength range component as a P-polarized light component or an S-polarized light component to radiate the diffracted light towards said first reflection type spatial optical modulator;
said polarization selective holographic optical device exhibiting the diffraction efficiency of not higher than 10% for the polarized light component of the illuminating light incident a second time thereon after phase modulation by said first reflection type spatial optical modulator, which polarized light component has a direction of polarization perpendicular to a direction of polarization of the polarized light component diffracted thereby at the time when the first wavelength range component of said illuminating light is first incident thereon, whereby not less than 70% of the diffracted polarized light component is transmitted through the optical device;
said polarization selective holographic optical device transmitting not less than 70% of the second wavelength range component to radiate the second wavelength range component towards said second reflection type spatial optical modulator;
said polarization selective holographic optical device diffracting the polarized light component having the direction of polarization perpendicular to the direction of polarization of the polarized light component of the second wavelength range component of the illuminating light re-incident thereon after phase modulation by said second reflection type spatial optical modulator, transmitted therethrough at the time when the second wavelength range component of said illuminating light is first incident thereon;
said projection optical system projecting the illuminating light of the first wavelength range component through said first reflection type spatial optical modulator and the polarization selective holographic optical device and the illuminating light of the second wavelength range component through said second reflection type spatial optical modulator and the polarization selective holographic optical device on said screen. - View Dependent Claims (59, 60, 61, 62, 63, 64, 65, 66, 67, 68, 69, 70, 71, 72, 73, 74, 75)
the reflection type spatial optical modulator has a rectangular profile with the long side direction of the rectangle coinciding with the direction of incidence of the illuminating light to the polarization selective holographic optical device. -
61. The image display apparatus according to claim 58 wherein
said illuminating optical system includes polarization transforming means for rotating the orientation of polarization through 90° - for one of two relatively perpendicular polarized light components of said illuminating light.
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62. The image display apparatus according to claim 58 wherein
the light source or the illuminating optical system includes time-sequential wavelength range switching means for temporally sequentially transmitting only a plurality of specified wavelength ranges of the total wavelength range of the illuminating light. -
63. The image display apparatus according to claim 58 wherein
the illuminating optical system has a polarization selective holographic optical device for correction having a bend angle opposite in sign to the bend angle of the polarization selective holographic optical device. -
64. The image display apparatus according to claim 58 wherein
the polarization selective holographic optical device for correction is the same type device as the polarization selective holographic optical device. -
65. The image display apparatus according to claim 58 further comprising:
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a coupling prism optically tightly bonded to the polarization selective holographic optical device and having at least a first optical surface irradiated with the illuminating light substantially perpendicularly and a second optical surface from which the light reflected by said reflection type spatial optical modulator is radiated substantially perpendicularly;
said illuminating light being incident on a light receiving surface of said polarization selective holographic optical device at an angle of incidence not less than 60° and
less than 90°
.
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66. The image display apparatus according to claim 65 wherein the coupling prism has a third optical surface including a light absorbing layer irradiated substantially perpendicularly with the regular reflected light of the illuminating light by said reflection type spatial optical modulator.
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67. The image display apparatus according to claim 58 wherein the projection optical system includes polarization selection means for selectively transmitting a component of the orientation of polarization of the light which is modulated by said reflection type spatial optical modulator and which is transmitted through said polarization selective holographic optical device.
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68. The image display apparatus according to claim 58 wherein the bend angle, as a difference between the angle of incidence of light on a hologram surface and the outgoing angle of diffraction of the polarization selective holographic optical device is not less than 30°
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69. The image display apparatus according to claim 58 wherein the hologram surface of the polarization selective holographic optical device and the reflecting surface of the reflection type spatial optical modulator exhibit optically non-parallel position relationships to each other.
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70. The image display apparatus according to claim 58 wherein the polarization selective holographic optical device is made up of a plurality of hologram layers having respective different wavelength dependencies of the diffraction efficiency.
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71. The image display apparatus according to claim 58 wherein the polarization selective holographic optical device is made up of a plurality of hologram layers having respective different reproducing light incidence angle dependencies of the diffraction efficiency.
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72. The image display apparatus according to claim 58 wherein the polarization selective holographic optical device comprises a plurality of holograms of respective different wavelength dependencies of the diffraction efficiency multiplexed in one hologram layer.
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73. The image display apparatus according to claim 58 wherein the polarization selective holographic optical device comprises a plurality of holograms of respective different reproducing light incidence angle dependencies of the diffraction efficiency multiplexed in one hologram layer.
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74. The image display apparatus according to claim 58 wherein
the polarization selective holographic optical device is formed of a liquid crystal material. -
75. The image display apparatus according to claim 58 wherein
the reflection type spatial optical modulator has a rectangular profile with the long side direction of the rectangle coinciding with the direction of incidence of the illuminating light to the polarization selective holographic optical device.
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76. An image display apparatus comprising:
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a light source for radiating illuminating light;
a polarization selective holographic optical device for diffracting the incident light, said device including a plurality of each of two areas having refractive index values exhibiting respectively different incidence polarization orientation dependencies, said areas being layered sequentially alternately;
an illuminating optical system for causing said illuminating light to be incident on said polarization selective holographic optical device;
a reflection type spatial optical modulator for modulating the state of polarization of the illuminating light diffracted by said polarization selective holographic optical device; and
a optical system for observing a virtual image, for guiding the illuminating light through said reflection type spatial optical modulator to the eye of a viewer;
said polarization selective holographic optical device, one of two areas of which exhibits refractive index anisotropy, with the other exhibiting refractive index isotropy, being irradiated by said illuminating optical system with the illuminating light at an angle of incidence not less than 30° and
less than 90°
with respect to a normal line to a light receiving surface thereof for said illuminating light, said polarization selective holographic optical device diffracting a P-polarized light component or an S-polarized light component of said illuminating light to radiate the diffracted light towards said reflection type spatial optical modulator;
said polarization selective holographic optical device exhibiting the diffraction efficiency of not higher than 10% for the polarized light component of the illuminating light incident a second time thereon after phase modulation by said reflection type spatial optical modulator, which polarized light component has a direction of polarization perpendicular to a direction of polarization of the polarized light component diffracted thereby at the time when the illuminating light is first incident thereon, whereby not less than 70% of the diffracted polarized light component is transmitted through the optical device;
said optical system for observing a virtual image guiding the light transmitted through said polarization selective holographic optical device towards the eye of a viewer. - View Dependent Claims (77, 78, 79, 80, 81, 82, 83, 84, 85, 86, 87, 88, 89, 90, 91, 92, 93, 94)
the reflection type spatial optical modulator has a rectangular profile with the long side direction of the rectangle coinciding with the direction of incidence of the illuminating light to the polarization selective holographic optical device. -
79. The image display apparatus according to claim 76 wherein
said illuminating optical system includes polarization transforming means for rotating the orientation of polarization through 90° - for one of two relatively perpendicular polarized light components of said illuminating light.
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80. The image display apparatus according to claim 76 wherein
the light source or the illuminating optical system includes time-sequential wavelength range switching means for temporally sequentially transmitting only a plurality of specified wavelength ranges of the total wavelength range of the illuminating light. -
81. The image display apparatus according to claim 76 wherein
the illuminating optical system has a polarization selective holographic optical device for correction having a bend angle opposite in sign to the bend angle of the polarization selective holographic optical device. -
82. The image display apparatus according to claim 81 wherein
the polarization selective holographic optical device for correction is the same type device as the polarization selective holographic optical device. -
83. The image display apparatus according to claim 76 further comprising:
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a coupling prism optically tightly bonded to the polarization selective holographic optical device and having at least a first optical surface irradiated with the illuminating light substantially perpendicularly and a second optical surface from which the light reflected by said reflection type spatial optical modulator is radiated substantially perpendicularly;
said illuminating light being incident on a light receiving surface of said polarization selective holographic optical device at an angle of incidence not less than 60° and
less than 90°
.
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84. The image display apparatus according to claim 83 wherein the coupling prism has a third optical surface including a light absorbing layer irradiated substantially perpendicularly with the regular reflected light of the illuminating light by said reflection type spatial optical modulator.
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85. The image display apparatus according to claim 76 wherein the optical system for observing a virtual image includes polarization selection means for selectively transmitting a component of the orientation of polarization of the light which is modulated by said reflection type spatial optical modulator and which is transmitted through said polarization selective holographic optical device.
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86. The image display apparatus according to claim 76 wherein said polarization selective holographic optical device permits the illuminating light as the P-polarized light to be incident thereon.
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87. The image display apparatus according to claim 76 wherein the bend angle as a difference between the angle of incidence of light on the hologram surface and the outgoing angle of diffraction is not less than 30°
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88. The image display apparatus according to claim 76 wherein the hologram surface of the polarization selective holographic optical device and the reflecting surface of the reflection type spatial optical modulator exhibit optically non-parallel position relationships to each other.
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89. The image display apparatus according to claim 76 wherein the polarization selective holographic optical device is made up of a plurality of hologram layers having respective different wavelength dependencies of the diffraction efficiency.
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90. The image display apparatus according to claim 76 wherein the polarization selective holographic optical device is made up of a plurality of hologram layers having respective different reproducing light incidence angle dependencies of the diffraction efficiency.
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91. The image display apparatus according to claim 76 wherein the polarization selective holographic optical device comprises a plurality of holograms of respective different wavelength dependencies of the diffraction efficiency multiplexed in one hologram layer.
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92. The image display apparatus according to claim 76 wherein the polarization selective holographic optical device comprises a plurality of holograms of respective different reproducing light incidence angle dependencies of the diffraction efficiency multiplexed in one hologram layer.
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93. The image display apparatus according to claim 76 wherein
the polarization selective holographic optical device is formed of a liquid crystal material. -
94. The image display apparatus according to claim 76 wherein
the reflection type spatial optical modulator has a rectangular profile with the long side direction of the rectangle coinciding with the direction of incidence of the illuminating light to the polarization selective holographic optical device.
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Specification