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US 2017/0322414 A1Published application
Optical waveguide using fresnel lenses
OwnerFusao Ishiiinventor
Life of this patent
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Abstract
An optical waveguide for a see-through display system using Fresnel lenses is disclosed. This invention enables high efficiency of light utilization, wavelength independence, high resolution and very small form factor. This display system is suitable for head-up-display and wearable display.
Claims10
An optical waveguide comprising:
- A waveguide made of a transparent plate and
- A Display and
- A Fresnel lens made of a transparent material having a first flat surface and a second surface whereon micro-ridges as saw-tooth are carved and have flat sloped minute surfaces whose slope angle is a free form function and
- Light beams projected from said display entering substantially perpendicular to the first flat surface of said Fresnel lens wherein
- Said light beams are reflected by the sloped surfaces on the second surface back to the first flat surface and the refractive index of the Fresnel lens of n2, the media adjacent to the first flat surface of n1, the reflecting angle at the sloped surface defined as the angle between the incident beam and the reflected beam of θ and the angle between the outgoing beam from the first surface and the normal direction of the first flat surface of φ satisfies the condition below:
- φ=Arc sin e(n2/n1*sin(2θ))>π/3(60°)
3 more elements
An optical waveguide comprising
- A display projecting image light beams and
- A pair of complimentary Fresnel lenses having saw-tooth shaped micro-ridges whose slope angle is a free form function and the slopes of the surfaces of two complimentary Fresnel lenses are parallel and the gap between said pair of complimentary Fresnel lenses is less than 1 mm wherein
- The image light beams of said display are projected into one of the Fresnel lens and the angle of a surface of ridge is φ and the angle between the incident light beam and the normal direction of the surface of ridge is θ and the refractive index of the Fresnel lens is n2 and the refractive index of the gap is n1 and the condition below is satisfied to pass the external light coming from outside scene through the pair of Fresnel lenses, although the internal light coming from the display is reflected toward a viewer:
- θ>arc sin e(n1/n2)>φ
1 more element
A manufacturing method having the steps of:
- Calculating a pattern of slopes of the surfaces of ridges of Free-Form-Fresnel lens/mirror and
- Preparing a exposure system capable to expose photoresist with a 2D spatial light modulator having grayscale and
- Preparing a substrate coated with photoresist and
- Exposing the photoresist with the intensity of the calculated pattern and
- Developing the exposed photoresist to make saw-tooth shaped ridges and
- Copying the shape of photoresist to a mold made of harder material
- Duplicating the shape from the mold to a plastic material by a method from a group of thermal press, UV casting, roll-to-roll thermal imprint and roll-to-roll UV casting.
4 more elements
Dependencies are inferred from the claim text.