Opposed Gratings in Waveguide Display for Large Exit Pupil
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Solution Overview
Problem
Conventional near-eye displays (NEDs) for virtual and augmented reality systems face challenges in achieving a compact and lightweight design while maintaining a large exit pupil, leading to bulky and heavy devices due to the need for large lenses.
Innovation Solution
A waveguide display system incorporating a light source, controller, and output waveguide with diffraction gratings that in-couple and decouple image light, expanding it in two dimensions to create a large exit pupil with a small form factor, allowing for a polychromatic display projected along multiple planes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If conventional lenses are used to achieve a large exit pupil, then the exit pupil size is improved, but the device becomes bulky and heavy
Solution Approach 1:
The patent replaces conventional mechanical lens systems with a waveguide-based optical system using diffraction gratings. The waveguide uses surface relief gratings to in-couple and out-couple light, eliminating the need for large mechanical lenses while achieving a large exit pupil. This substitution of mechanical optical elements with waveguide diffraction structures directly resolves the contradiction between exit pupil size and device weight.
Solution Approach 2:
The patent transitions from two-dimensional lens-based optics to three-dimensional waveguide propagation. By using light propagation through the waveguide thickness dimension and employing volume holographic gratings, the system achieves large exit pupil without requiring large lateral dimensions, thus reducing device bulk and weight while maintaining ease of operation.
2Ease of operation
If conventional lenses are used to achieve a large exit pupil, then the exit pupil size is improved, but the device becomes bulky
Solution Approach 1:
The patent replaces conventional mechanical lens systems with a waveguide-based optical system using diffraction gratings. The waveguide uses surface relief gratings to in-couple and out-couple light, eliminating the need for large mechanical lenses while achieving a large exit pupil. This substitution of mechanical optical elements with waveguide diffraction structures directly resolves the contradiction between exit pupil size and device weight.
Solution Approach 2:
The patent transitions from two-dimensional lens-based optics to three-dimensional waveguide propagation. By using light propagation through the waveguide thickness dimension and employing volume holographic gratings, the system achieves large exit pupil without requiring large lateral dimensions, thus reducing device bulk and weight while maintaining ease of operation.
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
The waveguide display system enables a compact, lightweight near-eye display with a large field of view and extended pupil, enhancing user experience by providing a high-resolution, full-colored image projection without the bulkiness associated with conventional designs.
Implementation Method 1
The first grating in-couples the image light (propagating along an input wave vector) emitted from the light source into the output waveguide, and the first grating has an associated first grating vector.
Implementation Method 2
The output waveguide includes a second and third grating (e.g., an output grating) that are associated with a second and third grating vector, respectively that together direct and decouple the expanded image light from the output waveguide, the output expanded image light having a wave vector that matches the input wave vector.
Implementation Method 3
The output waveguide expands the image light in two dimensions.
Data Source
AI summary
A waveguide display includes a light source assembly, an output waveguide, and a controller. The light source assembly emits an image light that propagates along an input wave vector. The output waveguide includes a waveguide body with two opposite surfaces. The output waveguide includes a first grating receiving an image light propagating along the input wave vector, a second grating, and a third grating positioned opposite to the second grating and outputting an expanded image light with wave vectors matching the input wave vector. The controller controls the illumination of the light source assembly to form a two-dimensional image.