AR Waveguide Polarization Structures for Field of View Expansion
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Solution Overview
Problem
Augmented reality displays have a limited field of view due to light loss from total reflection angles within the waveguide, where light is transmitted when the incident angle is smaller than the critical angle.
Innovation Solution
A diffractive optical structure with a first polarization structure on one face of the waveguide to transmit and reflect polarized light, and a second polarization structure on the opposite face to output polarized light, ensuring total reflection and minimizing light loss.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If a waveguide is used to guide light in augmented reality display, then the display can overlay virtual images on the real world, but the field of view is limited due to light loss from transmission when incident angle is smaller than critical angle
Solution Approach 1:
The patent changes the polarization state parameter of light by introducing polarization structures (first and second polarization structures) that selectively transmit and reflect light based on their polarization orientation. This transforms the light's polarization property to achieve total internal reflection at angles below the critical angle, preventing light loss and expanding the field of view.
Solution Approach 2:
The patent introduces polarization structures as intermediary elements between the light source and the waveguide output. These polarization structures act as mediators that control light propagation by utilizing polarization-dependent reflection and transmission, enabling precise control over light paths and preventing energy loss without requiring changes to the waveguide itself.
2Area of stationary object
If polarization structures are added to the waveguide to prevent light loss, then the field of view is improved, but the device complexity increases
Solution Approach 1:
The polarization structures serve multiple functions simultaneously: they act as polarization filters, reflection elements, and guidance components. By making these elements multi-functional, the patent reduces the need for separate components for each function, thereby limiting the increase in device complexity while achieving the desired field of view expansion.
Solution Approach 2:
The patent combines the polarization filtering and light reflection functions into integrated polarization structures that are directly formed on the waveguide surfaces. This merging of functions eliminates the need for separate optical components, simplifying the overall device structure while maintaining the capability to prevent light loss and expand the field of view.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This configuration enhances the field of view by preventing light loss within the waveguide, allowing users to simultaneously view augmented reality images and external images without distortion, regardless of the incident angle.
Implementation Method 1
a first polarization structure disposed on a first face of a waveguide, transmitting, to the outside of the waveguide, a first polarized light of light guided within the waveguide, and reflecting a second polarized light of the light to the inside of the waveguide
Implementation Method 2
the FOV of the augmented reality display is determined by a total reflection angle of light within a waveguide, but the light is lost because at least some thereof is transmitted when an incident angle of the light is smaller than a critical angle
Implementation Method 3
a second polarization structure disposed on a second face of the waveguide and outputting at least some of the second polarized light to the outside of the waveguide
Data Source
AI summary
Various embodiments may provide an augmented reality display having an improved FOV, and a waveguide device and diffractive optical structures thereof. The augmented reality display may comprise: a light source configured to generate light related to an image; and the waveguide device for outputting at least a part of the light. The waveguide device may comprise: a waveguide for guiding light therein; and the diffractive optical structures arranged on a first surface and a second surface of the waveguide. The diffractive optical structures may comprise: a first polarization structure arranged on the first surface of the waveguide to transmit, to the outside of the waveguide, first polarized light selected from external light and reflect, to the inside of the waveguide, second polarized light selected from light guided inside the waveguide device; and a second polarization structure arranged on the second surface of the waveguide to output at least a part of the second polarized light to the outside of the waveguide.