Tunable Bulk-Reflector Waveguide for Eye-Position Light Control
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Solution Overview
Problem
Near-eye displays face challenges with low light utilization efficiency in pupil replicating waveguides, leading to increased brightness requirements and device size and weight, especially in augmented reality systems where internal image light needs to compete with external light.
Innovation Solution
A waveguide with tunable bulk mirrors having individually controllable reflectivity and direction, controlled by voltage or liquid crystal layers, to optimize the spatial distribution of image light portions and match eye location and field of view.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If traditional pupil replicating waveguides are used in near-eye displays, then the device can present content to the user, but the light utilization efficiency is low requiring increased brightness and larger device size
Solution Approach 1:
The waveguide incorporates tunable bulk mirrors with variable reflectivity that can be dynamically adjusted based on eye tracking data. This dynamic adaptation allows the system to optimize light distribution in real-time, directing more light to the actual eye location and reducing overall brightness requirements while improving light utilization efficiency.
Solution Approach 2:
The system changes the reflectivity parameter of bulk mirrors based on detected eye position. By adjusting the reflectivity parameter of specific mirrors along the light path, the waveguide optimizes the spatial distribution of out-coupled light to match the user's eye location, thereby improving light utilization efficiency without increasing overall brightness.
2Loss of energy
If traditional pupil replicating waveguides are used in near-eye displays, then the device can present content to the user, but the device size and weight increase
Solution Approach 1:
The waveguide incorporates tunable bulk mirrors with variable reflectivity that can be dynamically adjusted based on eye tracking data. This dynamic adaptation allows the system to optimize light distribution in real-time, directing more light to the actual eye location and reducing overall brightness requirements while improving light utilization efficiency.
Solution Approach 2:
The system changes the reflectivity parameter of bulk mirrors based on detected eye position. By adjusting the reflectivity parameter of specific mirrors along the light path, the waveguide optimizes the spatial distribution of out-coupled light to match the user's eye location, thereby improving light utilization efficiency without increasing overall brightness.
3Ease of operation
If traditional pupil replicating waveguides are used in near-eye displays, then the device can present content to the user, but the light distribution does not match eye location and field of view
Solution Approach 1:
The system implements a feedback loop using eye tracking to detect eye position and adjust bulk mirror reflectivity accordingly. The eye tracker provides real-time feedback on eye location, and the controller uses this information to dynamically adjust the reflectivity of appropriate mirrors, ensuring that out-coupled light is precisely directed to the user's eye while improving light utilization efficiency.
Solution Approach 2:
The waveguide incorporates tunable bulk mirrors with variable reflectivity that can be dynamically adjusted based on eye tracking data. This dynamic adaptation allows the system to optimize light distribution in real-time, directing more light to the actual eye location and reducing overall brightness requirements while improving light utilization efficiency.
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
Improves light utilization efficiency by redistributing image light to the eye, reducing brightness needs and overall power consumption, resulting in a more compact and efficient display device.
Implementation Method 1
a liquid crystal layer configured to control a state of polarization of the image light propagating along the zigzag light path
Implementation Method 2
image light propagating within the waveguide body along a zigzag light path defined by alternating reflections of the image light from the first and second surfaces
Data Source
AI summary
A waveguide for conveying image light in a display device is disclosed. The waveguide comprises a waveguide body, an input coupler configured to couple the image light into the waveguide body for propagating the image light within the waveguide body along a zigzag light path, and a plurality of slanted bulk mirrors disposed along the zigzag light path within the waveguide body and having a tunable reflectivity parameter for controlling a spatial distribution of image light portions out-coupled from the waveguide body by the plurality of slanted bulk mirrors. The waveguide may include a plurality of slanted polarization-selective bulk mirrors, and a liquid crystal layer configured to alter the polarization of the image light, the liquid crystal layer being disposed between a backplane electrode and a pixelated electrode configured to control the liquid crystal layer by application of a spatially-varying voltage profile.