OPTICAL DEVICE, AND VIRTUAL IMAGE DISPLAY
First Claim
1. An optical device including an optical waveguide upon which a group of parallel light beams different in traveling direction from each other are incident and from which the group of parallel light beams go out after propagated by repeated total reflection through it, the optical waveguide comprising:
- a first reflection-type volume hologram grating to diffract and reflect, in the light beam-incident section thereof, the group of parallel light beams as they are so as to meet internal total reflection condition in the optical wave guide; and
a second reflection-type volume hologram grating to diffract and reflect, in a section thereof from which the group of parallel light beams are to go out, the group of parallel light beams as they are so as to go out of the optical waveguide, pitches of interference fringes on the hologram surfaces of the first and second reflection-type volume hologram gratings being equal to each other;
in at least the second reflection-type volume hologram grating, the angle formed between the interference fringes and hologram surfaces being varied continuously or stepwise within the hologram in relation to the main incident light beam so as to meet the Bragg condition; and
at least parts of the group of parallel light beams different in traveling direction from each other and propagated from the incident to outgoing section in the optical waveguide by repeated total reflection have different numbers of total reflection respectively depending upon the difference in traveling direction.
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Accused Products
Abstract
There is provided an optical device including an optical waveguide upon which a group of parallel light beams different in traveling direction from each other are incident and from which the group of parallel light beams go out after propagated by repeated total reflection through it. The optical waveguide includes a first reflection-type volume hologram grating, and a second reflection-type volume hologram grating. The pitches of interference fringes on the hologram surfaces of the first and second reflection-type volume hologram gratings are equal to each other. In at least the second reflection-type volume hologram grating, the angle formed between the interference fringes and hologram surfaces are varied continuously or stepwise within the hologram in relation to the main incident light beam so as to meet the Bragg condition. Therefore, it is possible to reduce the unevenness of color and brightness due to angles of view.
141 Citations
46 Claims
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1. An optical device including an optical waveguide upon which a group of parallel light beams different in traveling direction from each other are incident and from which the group of parallel light beams go out after propagated by repeated total reflection through it, the optical waveguide comprising:
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a first reflection-type volume hologram grating to diffract and reflect, in the light beam-incident section thereof, the group of parallel light beams as they are so as to meet internal total reflection condition in the optical wave guide; and
a second reflection-type volume hologram grating to diffract and reflect, in a section thereof from which the group of parallel light beams are to go out, the group of parallel light beams as they are so as to go out of the optical waveguide, pitches of interference fringes on the hologram surfaces of the first and second reflection-type volume hologram gratings being equal to each other;
in at least the second reflection-type volume hologram grating, the angle formed between the interference fringes and hologram surfaces being varied continuously or stepwise within the hologram in relation to the main incident light beam so as to meet the Bragg condition; and
at least parts of the group of parallel light beams different in traveling direction from each other and propagated from the incident to outgoing section in the optical waveguide by repeated total reflection have different numbers of total reflection respectively depending upon the difference in traveling direction. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14)
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15. A virtual image display, comprising:
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a light source;
a collimation optical system to form light beams emitted from the light source into parallel light beams;
a scanning optical system to scan the parallel beams; and
an optical waveguide upon which a group of parallel light beams formed in the scanning optical system to travel in different directions are incident and from which the group of parallel light beams go out toward a viewer'"'"'s pupil after propagated by repeated total reflection through it, wherein the optical waveguide including;
a first reflection-type volume hologram grating to diffract and reflect, in the light beams-incident section thereof, the group of parallel light beams as they are at an angle that meets the total reflection condition in the optical waveguide; and
a second reflection-type volume hologram grating to diffract and reflect, in a section thereof from which the group of parallel light beams are to go out, the group of parallel light beams as they are at an angle at which they go out of the optical waveguide, pitches of interference fringes on the hologram surfaces of the first and second reflection-type volume hologram gratings being equal to each other;
in at least the second reflection-type volume hologram grating, the angle formed between the interference fringes and hologram surfaces being varied continuously or stepwise within the hologram in relation to the main incident light beam so as to meet the Bragg condition; and
at least parts of the group of parallel light beams different in traveling direction from each other and propagated through the optical waveguide by repeated total reflection have different numbers of total reflections, respectively, depending upon the difference in traveling direction. - View Dependent Claims (16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30)
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31. A virtual image display, comprising:
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an image display element;
a collimation optical system to form light beams emitted from pixels of the image display element into parallel light beams; and
an optical waveguide upon which a group of parallel light beams formed in the collimation optical system and from which the group of parallel light beams go out toward a viewer'"'"'s pupil after propagated by total reflection through it, wherein the optical waveguide including;
a first reflection-type volume hologram grating to diffract and reflect, in the light beam-incident section thereof, the group of parallel light beams as they are so as to meet the internal total reflection condition in the optical waveguide; and
a second reflection-type volume hologram grating to diffract and reflect, in a section thereof from which the group of parallel light beams are to go out, the group of parallel light beams as they are so as to go out of the optical waveguide, pitches of interference fringes on the hologram surfaces of the first and second reflection-type volume hologram gratings being equal to each other;
in at least the second reflection-type volume hologram grating, the angle formed between the interference fringes and hologram surfaces being varied continuously or stepwise within the hologram in relation to the main incident light beam so as to meet the Bragg condition; and
at least parts of the group of parallel light beams different in traveling direction from each other and propagated from the incident to outgoing section in the optical waveguide by repeated total reflection have different numbers of total reflections, respectively, depending upon the difference in traveling direction. - View Dependent Claims (32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46)
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Specification