Retroreflector Waveguide Eyepiece for AR Light Loss
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Solution Overview
Problem
Existing augmented reality display systems face challenges in achieving high efficiency and brightness due to light loss in the eyepiece units.
Innovation Solution
The integration of a retroreflector with a waveguide layer in the eyepiece unit recycles light and enhances the effective coupling efficiency of projected light, addressing the issue of light loss.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If a waveguide layer is used to guide light in augmented reality display systems, then the field of view and pupil size are improved, but light loss occurs due to insufficient coupling efficiency
Solution Approach 1:
The retroreflector recovers light that would otherwise be lost by reflecting it back into the waveguide layer, allowing the light to be redirected to the user's eye. This recovers wasted light energy and converts it into useful illumination, directly addressing the light loss problem while maintaining brightness.
Solution Approach 2:
The retroreflector creates a feedback mechanism where light that misses the initial coupling is reflected back and given another chance to couple into the waveguide. This feedback loop continuously recycles light until it successfully couples, maximizing light utilization efficiency.
2Illumination intensity
If the coupling efficiency of projected light into the waveguide layer is increased, then system brightness is improved, but the complexity of the eyepiece unit increases
Solution Approach 1:
The retroreflector is integrated with the waveguide layer to form a unified optical assembly. By merging these components, the patent achieves improved light coupling efficiency without proportionally increasing overall system complexity, as the retroreflector and waveguide work together as a coordinated unit.
Solution Approach 2:
The retroreflector acts as an intermediary element between the light source and the waveguide layer. It mediates the interaction by reflecting stray light back toward the waveguide, improving coupling efficiency without requiring direct modification of the waveguide structure itself.
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 solution results in improved system brightness and performance by increasing the efficiency of light coupling and reducing artifacts, thereby enhancing the overall user experience in augmented reality applications.
Implementation Method 1
an incoupling diffractive optical element disposed on the incident light surface. The incoupling diffractive optical element is configured to incouple a first portion of the beam of light and to propagate the first portion of the beam of light by total internal reflection
Implementation Method 2
The incoupling diffractive optical element is configured to incouple a first portion of the beam of light and to propagate the first portion of the beam of light by total internal reflection
Implementation Method 3
The retroreflector is configured to retroreflect the second portion of the beam of light along a reflected direction opposite to the first direction
Data Source
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AI summary
A display system includes projection optics configured to project a beam of light in a first direction and an eyepiece unit including a first waveguide layer disposed in a first lateral plane and including an incident light surface and an opposing surface opposite the incident light surface and an incoupling diffractive optical element disposed on the incident light surface. The incoupling diffractive optical element is configured to incouple a first portion of the beam of light and to propagate the first portion of the beam of light by total internal reflection in a second direction and transmit a second portion of the beam of light along the first direction. The eyepiece also includes a retroreflector disposed adjacent the opposing surface. The retroreflector is configured to retroreflect the second portion of the beam of light along a reflected direction opposite to the first direction.