Structure and manufacturing method of holographic optical elements
AssigneeNtt Docomo, Inc.
InventorsFusao Ishii, Mikiko Nakanishi, Kazuhiko Takahashi, Yuji Aburakawa
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Abstract
Manufacturing methods are disclosed to produce a seamless hologram using a free-form-lens enabling arbitrary adjustment of diffraction angle and also a thick hologram made of transparent inorganic materials and heat and UV resistant is disclosed.
Claims9
A see-through display comprising
- a display device and
- a projection lens system which projects the image of said display device
- a combiner which integrates a real image in front of a viewer and the projected image and
- a hologram on the combiner comprising a photopolymer wherein
- the photopolymer exposed for recording with two coherent beams and
- at least one of the beams is focused on the photopolymer with at least one free-form lens and the entire viewing surface of the photopolymer is exposed seamlessly by the free-form lens
The see-through display of claim-1 wherein
- the hologram is exposed with at least three colors.
The see-through display of claim-1 wherein
- one of recording beams is collimated.
The see-through display of claim-1 wherein
- the two recording beams are combined with a beam splitter,
A manufacturing method having the steps of:
- calculating a function which enables to know the diffraction angle of hologram to maximize the resolution of image of combiner of see-through display and
- calculating the tilt angle of micro stripe in the hologram and
- calculating the angles of two recording beams so that the middle angle between said two beams coincide with said tilt angle of micro stripe in the hologram and
- design at least one tree-form-lens so that the incident beams to the hologram coincide with said angles of two recording beams.
A see-through display comprising
- a display device and
- a projection lens system which projects the image of said display device and
- a combiner which integrates a real image in front of a viewer and the projected image and
- a hologram on the combiner wherein
- a hologram is made of transparent and inorganic material comprising
- a transparent substrate and
- at least two patterned layers of inorganic material whose refractive indices differ from that of said substrate and
- the patterned layers have a periodical structure and diffract incident light whose incident angle and wavelength and the pitch of the periodical structure meet Bragg's law.
The see-through display of claim-6 wherein
- the substrate is made of oxide and substantially transparent.
The see-through display of claim-6 wherein
- the patterned layers are made of nitride and substantially transparent.
The see-through display of claim-6 wherein
- the patterned layers are at least 2 microns thick.
Dependencies are inferred from the claim text.