Asymmetric Diffractive Waveguide for Low-Power AR Displays
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Solution Overview
Problem
Conventional diffractive optical waveguides for AR glasses require high energy consumption due to the need for two sets of AR display modules and optical machines, which contradicts the low energy consumption requirement for smart wearables.
Innovation Solution
A diffractive optical waveguide design with a waveguide substrate having a coupling-in region and two coupling-out regions for left and right eyes, utilizing a coupling-in grating for total reflection and coupling-out gratings for diffraction, where the center of the coupling-in region deviates from the center line connecting the coupling-out regions, allowing for ergonomic placement and reducing the need for dual optical machines.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If two sets of AR display modules and optical machines are used for left and right eyes, then the light coupling effectiveness is improved, but the energy consumption increases and device complexity increases
Solution Approach 1:
The patent combines two separate waveguide substrates into a single integrated waveguide substrate that serves both left and right eyes. The coupling-in gratings for both eyes are integrated onto one substrate, sharing common optical paths and structural support, thereby reducing the number of optical machines required while maintaining effective light coupling to both eyes
Solution Approach 2:
The single waveguide substrate performs multiple functions: it couples light for both left and right eyes simultaneously, provides structural support for both optical paths, and enables pupil expansion for both eyes through its integrated design. This multi-functional approach eliminates the need for separate dedicated substrates for each eye
2Reliability
If two sets of AR display modules and optical machines are used for left and right eyes, then the light coupling effectiveness is improved, but the device complexity increases
Solution Approach 1:
The patent merges two separate waveguide substrates into one integrated substrate that handles both left and right eye optical paths. The coupling-in gratings, waveguide layers, and structural components are consolidated into a single substrate assembly, reducing the overall number of parts and simplifying the optical system architecture
Solution Approach 2:
Within the integrated substrate, the patent segments the optical paths into distinct first and second coupling-in gratings regions, allowing independent optimization for left and right eyes while maintaining physical integration. This segmentation enables effective light coupling for each eye without requiring completely separate substrate assemblies
3Shape
If the center of coupling-in region is positioned on the center line between coupling-out regions, then the structural symmetry is improved, but the ergonomic comfort deteriorates
Solution Approach 1:
The patent intentionally positions the center of the coupling-in region off the center line connecting the first and second coupling-out regions. This asymmetric arrangement allows the optical machine to be placed in a location that better matches the user's nose bridge anatomy, improving ergonomic comfort and wearing stability while maintaining functional symmetry in the optical performance for both eyes
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 design simplifies the structure, reduces assembly difficulty, and lowers power consumption by enabling pupil expansion without requiring two sets of diffractive waveguides and optical machines, while maintaining effective light coupling to the user's eyes.
Implementation Method 1
a coupling-in grating disposed on or in the waveguide substrate and located in the coupling-in region and configured to couple input light into the waveguide substrate
Implementation Method 2
cause the light to propagate within the waveguide substrate through total reflection
Implementation Method 3
the first coupling-out grating and the second coupling-out grating both configured to couple at least a portion of light propagating therein out of the waveguide substrate by diffraction
Data Source
AI summary
The present application provides a diffractive optical waveguide for optical pupil expansion and a display device, comprising a waveguide substrate having a coupling-in region in which a coupling-in grating is located and a coupling-out region. A first and a second diffractive light obtained by the input light diffracted by the coupling-in grating are respectively totally reflected in the waveguide substrate and directed to a first and a second coupling-out regions. A first coupling-out grating disposed in the first coupling-out region and a second coupling-out grating disposed in the second coupling-out region both are configured to couple at least a portion of light propagating therein out of the waveguide substrate by diffraction. The first and the second coupling-out regions are respectively located at both sides of the coupling-in region. A center of the coupling-in region deviates from the center line connecting the centers of the first and the second coupling-out regions.