Lightfield Waveguide Eye Tracking for AR
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Solution Overview
Problem
Implementing eye tracking in small form-factor packages for artificial reality systems is challenging due to stability and calibration issues with traditional methods, which require efficient and accurate tracking of a user's eye position and orientation.
Innovation Solution
A waveguide-based eye tracker is introduced, utilizing a plurality of grating structures, IR light sources, and a detector array, where IR light is coupled into waveguides and reflected signals are used to determine the eye's position and orientation, allowing for precise tracking within a small package.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional hot-mirror based eye tracking is used, then eye tracking functionality is achieved, but device size and complexity increase making it difficult to implement in small form-factor packages
Solution Approach 1:
The patent combines the eye tracking functionality with the existing waveguide display optics by integrating infrared light sources and detectors directly into the waveguide structure. The same waveguide that delivers visual content to the user's eye also serves as the optical path for eye tracking, eliminating the need for separate hot-mirror based tracking hardware and reducing overall device complexity and size.
Solution Approach 2:
The waveguide structure performs multiple functions simultaneously: it acts as both the display optics for delivering virtual reality content to the user's eye and as the optical pathway for eye tracking. The infrared light sources and detectors integrated into the waveguide enable the system to perform both display and tracking functions through a single optical structure, reducing the number of components needed.
2Measurement precision
If traditional imaging-based eye tracking is used, then gaze direction can be determined, but power consumption and computing cycles increase
Solution Approach 1:
The patent extracts only the essential information needed for gaze direction determination by using infrared light reflection patterns from the cornea and retina, rather than capturing full images of the eye. The detector array captures reflected infrared light signals that directly indicate gaze direction, eliminating the need for complex image processing and reducing computational requirements and power consumption.
Solution Approach 2:
The patent replaces the complex imaging and image processing system with a simpler optical detection system based on infrared light reflection. Instead of using visible light cameras that require complex image formation and processing, the system uses infrared light sources and detectors that directly measure reflection patterns correlated with gaze direction, reducing computational load and power consumption.
3Use of energy by moving object
If resolution is reduced in non-foveal regions, then power consumption decreases, but visual experience quality may be compromised
Solution Approach 1:
The patent uses dynamic eye tracking to continuously monitor the user's gaze position and adjust the rendering resolution in real-time. Based on the detected eye position and orientation, the system dynamically allocates higher pixel density to the foveal region where the user is currently looking, while using lower resolution in peripheral regions. This dynamic adjustment ensures optimal visual quality where needed while minimizing power consumption in less critical areas.
Solution Approach 2:
The patent applies different pixel densities to different regions of the display based on the user's current gaze position. The foveal region, which corresponds to the center of the user's visual attention, receives maximum pixel density for high visual quality, while peripheral regions receive progressively lower resolution. This local quality variation ensures that visual experience is optimized for the area the user is actually looking at while reducing overall power consumption.
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 provides accurate eye tracking with improved performance and reduced size and weight compared to traditional methods, enabling efficient power consumption and computing cycles while maintaining visual experience quality.
Implementation Method 1
The light emitted from each light source is coupled into the one or more waveguides and propagates through the one or more waveguides
Implementation Method 2
The light can be out coupled from the one or more waveguides towards a user's eye via one or more of the grating structures
Implementation Method 3
Depending on an orientation of the user's eye relative to the emitted IR light, some of the IR light is reflected back towards the one or more waveguides
Data Source
AI summary
An eye tracker for determining a position of an eye, which may be integrated into a head-mounted display. The eye tracker includes at least one waveguides with an array of grating structures, an array of light sources, a detector, and a controller. The controller activates at least one light source at a time to emit at least one light beam that propagates through the at least one waveguide and couple out via the array of grating structures towards a user's eye. Light signals reflected from the user's eye and skin surfaces are coupled into the at least one waveguide and propagate to the detector that captures the reflected light signals. The controller calculates magnitudes of the reflected light signals to obtain a signature of converted light signals, and determines a position and orientation of the user's eye based on the signature of converted light signals.