Co-axial Eye Tracking in Mixed Reality Waveguides
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Solution Overview
Problem
Current eye tracking systems in see-through, near-eye, mixed reality display devices face challenges in accurately tracking eye movements due to obstructions like droopy eyelids and styes, and they often require complex computations and are hindered by the need to capture data off-axis, which affects illumination and data capture efficiency.
Innovation Solution
The integration of eye tracking and display functions using shared optics in a see-through, near-eye, mixed reality display device, where infrared and visible illumination are directed along the optical axis through a planar waveguide with wavelength selective filters, allowing for better illumination and data capture of the eye, including infrared reflections, to simplify computations and improve data capture.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If eye tracking systems capture data off-axis, then they can be implemented in see-through display devices, but they are hindered by obstructions like droopy eyelids and styes and suffer from poor illumination
Solution Approach 1:
Instead of capturing eye data off-axis from the side, the patent inverts the approach by positioning the eye tracking system co-axially with the display optical axis. This allows the system to capture eye reflections along the same path as the display light, eliminating obstructions from droopy eyelids and styes that plague off-axis systems.
Solution Approach 2:
The patent makes the display optical system serve dual functions: displaying images to the user and tracking eye movements. By using the display's existing optical path, waveguide, and coatings for both purposes, the system eliminates the need for separate eye tracking hardware that would add complexity and potential obstructions.
2Adaptability or versatility
If separate eye tracking hardware is added to display devices, then eye tracking functionality is achieved, but device complexity increases
Solution Approach 1:
The patent makes the display optical system serve dual functions: displaying images to the user and tracking eye movements. By using the display's existing optical path, waveguide, and coatings for both purposes, the system eliminates the need for separate eye tracking hardware that would add complexity.
Solution Approach 2:
The patent merges the eye tracking system with the display system by integrating the infrared illumination source and sensor into the existing display optical path. The same waveguide and wavelength selective filters that direct display light are used to direct eye tracking light, combining two functions into one unified system.
3Illumination intensity
If eye tracking systems use co-axial alignment with display optical axis, then illumination and data capture are improved, but filtering separate wavelengths becomes more challenging
Solution Approach 1:
The patent uses different wavelengths (colors) of light to separate functions: visible light for display and infrared light for eye tracking. The wavelength selective filters are designed to reflect infrared wavelengths while transmitting visible wavelengths, allowing co-axial operation without interference between the two functions.
Solution Approach 2:
The patent introduces wavelength selective filters as intermediary elements in the optical path. These filters act as mediators that selectively direct different wavelengths along different paths - reflecting infrared eye tracking light to the sensor while allowing visible display light to reach the user's eye.
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 approach enhances eye tracking accuracy and data capture, improving applications such as gaze determination, pupil tracking, and biometric identification by providing better illumination and tolerance to individual facial features, while maintaining a user's direct view of the real world.
Implementation Method 1
One or more wavelength selective filters are positioned in the waveguide in co-axial alignment with the optical axis of the respective display optical system. The one or more filters direct infrared and visible illumination out of the respective planar waveguide.
Implementation Method 2
The one or more filters direct infrared reflections into the planar waveguide.
Implementation Method 3
An infrared illumination source is positioned for having its infrared illumination optically coupled into the planar waveguide.
Implementation Method 4
a see-through, planar waveguide positioned to be seen through by the respective eye
Data Source
AI summary
Technology is provided for an integrated eye tracking and display system for a see-through, near-eye, mixed reality display device. Image data and IR illumination for eye tracking are optically coupled into a respective see-through, planar waveguide positioned to be seen through by each eye in a respective display optical system of the display device. The respective planar waveguide comprises one or more wavelength selective filters positioned to be co-axial with an optical axis of the respective display optical system. The wavelength selective filters direct IR and visible illumination out of the planar waveguide in the direction of the respective eye and direct IR reflections, including reflections from the eye, into the planar waveguide. The reflections are optically coupled out of the waveguide to an IR sensor which generates eye tracking data based on the reflections.