Beam expanding optical element, beam expansion method, image display apparatus, and head-mounted display
First Claim
1. A beam expanding optical element, comprising:
- an optical waveguide member that has two mutually opposite faces that respectively have mutually parallel flat surfaces;
a first holographic diffractive optical element arranged at one location on the flat surface of the optical waveguide member, the first holographic diffractive optical element diffracting light incident from outside on the optical waveguide member such that the light is then totally reflected inside the optical waveguide member; and
a second holographic diffractive optical element arranged at another location on the flat surface of the optical waveguide member, the second holographic diffractive optical element diffracting, according to diffraction efficiency thereof, part of the light incident thereon after being guided inside the optical waveguide member such that this part of the light is then emitted to outside substantially parallel to the light incident on the optical waveguide member, the second holographic diffractive optical element simultaneously totally reflecting the rest of the light incident thereon,wherein the first and second holographic diffractive optical elements each have interference fringes with n different pitches (where n is a natural number equal to or greater than two) so as to diffract light of n different wavelengths at substantially equal angles.
1 Assignment
0 Petitions
Accused Products
Abstract
A first HOE and a second HOE are respectively arranged on two opposite faces of an optical waveguide member. The first HOE diffracts light incident from the outside on the optical waveguide member such that the light is then totally reflected inside the optical waveguide member and is thereby directed to the second HOE. The second HOE diffracts, according to the diffraction efficiency thereof, part of the light incident thereon after being guided inside the optical waveguide member such that this part of the light is then emitted to the outside substantially parallel to the light incident on the optical waveguide member, and the second HOE simultaneously totally reflects the rest of the light incident thereon. The second HOE repeats such emission and total reflection. The first and second HOEs each have interference fringes with n different pitches (where n is a natural number equal to or greater than two) to diffract light of n different wavelengths at substantially equal angles. Thus, even when light of n different wavelengths is incident on the optical waveguide member, the second holographic diffractive optical element emits it to the outside with substantially equal pitches for the light of the n different wavelengths.
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Citations
24 Claims
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1. A beam expanding optical element, comprising:
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an optical waveguide member that has two mutually opposite faces that respectively have mutually parallel flat surfaces; a first holographic diffractive optical element arranged at one location on the flat surface of the optical waveguide member, the first holographic diffractive optical element diffracting light incident from outside on the optical waveguide member such that the light is then totally reflected inside the optical waveguide member; and a second holographic diffractive optical element arranged at another location on the flat surface of the optical waveguide member, the second holographic diffractive optical element diffracting, according to diffraction efficiency thereof, part of the light incident thereon after being guided inside the optical waveguide member such that this part of the light is then emitted to outside substantially parallel to the light incident on the optical waveguide member, the second holographic diffractive optical element simultaneously totally reflecting the rest of the light incident thereon, wherein the first and second holographic diffractive optical elements each have interference fringes with n different pitches (where n is a natural number equal to or greater than two) so as to diffract light of n different wavelengths at substantially equal angles. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23)
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24. A method for beam expansion, comprising:
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a step of diffracting, by using a first holographic diffractive optical element arranged on a flat surface on an optical waveguide member, light of n different wavelengths (where n is a natural number equal to or greater than two) incident thereon at substantially equal angles; a step of totally reflecting the light diffracted by the first holographic diffractive optical element so as to make the light travel inside the optical waveguide member; and a step of receiving the light traveling inside the optical waveguide member with a second holographic diffractive optical element so that the second holographic diffractive optical element diffracts part of the light so as to emit this part of the light to outside substantially parallel to incident light and simultaneously totally reflect the rest of the light, the second holographic diffractive optical element diffracting the light of the n different wavelengths at substantially equal angles.
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Specification