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US 2003/0156325 A1Published application
Optical element, optical functional device, polarization conversion device, image display apparatus, and image display system
AssigneeCanon Kabushiki Kaisha
InventorHikaru Hoshi
Life of this patent
Estimating the term…
Abstract
The present invention discloses various embodiments of optical elements each having a plurality of periodic structures in which each period is smaller than the wavelength of usable light. For example, there are disclosed an embodiment in which a desired phase difference can be obtained at at least two wavelengths in a used wavelength region, an embodiment in which periodic directions of a plurality of structures are perpendicular to each other, and an embodiment in which the difference in refractive index between individual structures for a predetermined polarization component is set to a predetermined value or less.
Claims18
An optical element comprising:
- a substrate;
- and
- a plurality of periodic structures laminated to each other and provided on the substrate, the periodic structures each having a period smaller than the predetermined wavelength of usable light;
- wherein, when the plurality of periodic structures comprises k periodic structures (k is an integer of one or more) each having a period in a first direction and l periodic structures (l is an integer of zero or more) each having a period in a second direction perpendicular to the first direction, the following equation is satisfied for two designed wavelengths λ1 and λ2 in a visible light region:
- 7 ( ∑ i = 1 k Δ n i d i - ∑ j = 0 I Δ n j d j ) / λ 1 = ( ∑ i = 1 k Δ n i ′ d i - ∑ j = 0 I Δ n j ′ d j ) / λ 2
- where Δni indicates the difference of the refractive index of an ith periodic structure, having the period in the first direction, for TE polarized light from that for TM polarized light with respect to designed wavelength λ1;
- di indicates the thickness of the ith periodic structure having the period in the first direction;
- Δnj indicates the difference of the refractive index of a jth periodic structure, having the period in the second direction, for TE polarized light from that for TM polarized light with respect to designed wavelength λ1;
- dj indicates the thickness of the jth periodic structure having the period in the second direction;
- Δn′i indicates the difference of the refractive index of the ith periodic structure, having the period in the first direction, for TE polarized light from that for TM polarized light with respect to designed wavelength λ2;
- and
- Δn′j indicates the difference of the refractive index of the jth periodic structure, having the period in the second direction, for TE polarized light from that for TM polarized light with respect to designed wavelength λ2, the TE polarized light being polarized light having a polarization direction perpendicular to the periodic direction of the periodic structure, the TM polarized light being polarized light having a polarization direction parallel to the periodic direction of the periodic structure.
9 more elements
An optical element comprising:
- a substrate;
- a first periodic structure provided on the substrate, the period in a first direction being smaller than the wavelength of usable light;
- and
- a second periodic structure provided above the substrate, the period in a second direction, which is perpendicular to the first direction, being smaller than the wavelength of the usable light.
1 more element
An optical element comprising:
- a substrate;
- a plurality of periodic structures laminated to each other and provided on the substrate, each period being smaller than the wavelength of usable light;
- wherein the incident light has a first polarized light having a first polarization component, and the difference in effective refractive index between said plurality of periodic structures for the first polarized light is 0.2 or less.
An optical element comprising:
- a first substrate;
- a first periodic structure having a period smaller than the wavelength of usable light;
- a second periodic structure having a period smaller than the wavelength of the usable light, the period being in the direction approximately perpendicular to that of the period of the first structure;
- and
- a second substrate,
- wherein the first substrate, the first periodic structure, the second periodic structure, and the second substrate are provided in that order from a light incident side to a light emission side.
3 more elements
A method for manufacturing an optical element comprising the steps of:
- forming a first periodic structure, having a period smaller than a predetermined wavelength of usable light, on a first substrate;
- forming a second periodic structure, having a period smaller than the predetermined wavelength of the usable light, on a second substrate;
- and
- laminating the first substrate to the second substrate so that the first periodic structure and the second periodic structure oppose each other, and that the periodic directions thereof are approximately perpendicular to each other.
1 more element
Dependencies are inferred from the claim text.