Waveguide Eye-Tracking Optics for Unobstructed Head-Worn Displays
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Solution Overview
Problem
The integration of eye tracking sensors and lighting into helmets or head-worn displays is constrained by limited space and off-axis eye viewing, obstructing the display path and complicating sensor placement.
Innovation Solution
An optical assembly that integrates an illuminator and camera outside the optical path using waveguides to vector luminous output and ocular images into the path without obstructing it, allowing for clear image capture and display.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Difficulty of detecting and measuring
If image sensor and lighting are placed within the helmet assembly to enable eye tracking, then eye tracking capability is improved, but device complexity and space constraints are worsened
Solution Approach 1:
The patent extracts the image sensor and illuminator from the helmet assembly and positions them outside the optical path. The waveguides then transfer the optical signals (illumination and captured eye images) into the optical path, eliminating the need for complex sensor integration within the limited helmet space while maintaining eye tracking functionality.
Solution Approach 2:
The waveguide acts as an intermediary element that transfers optical signals between the external sensor/illuminator and the optical path. This mediator enables the separation of functional components (sensor, illuminator, display) while maintaining optical coupling, thereby reducing device complexity and allowing flexible placement of tracking sensors.
2Measurement precision
If tracking sensors are placed within the helmet assembly, then eye tracking data quality is improved, but installation flexibility is worsened due to limited space
Solution Approach 1:
By extracting the image sensor and illuminator from the helmet assembly and positioning them externally, the system maintains high eye tracking data quality through the waveguide-coupled optical path while significantly improving installation flexibility. The external placement allows sensors to be positioned optimally for data capture without being constrained by the limited internal helmet space.
3Measurement precision
If illuminator and camera are integrated into the optical path, then image capture quality is improved, but obstruction of display path is worsened
Solution Approach 1:
The patent extracts the illuminator and camera from the optical path and positions them externally. The waveguides then couple these external components to the optical path, enabling high-quality image capture without obstructing the display path. The waveguides allow the optical path to remain clear for display while still enabling illumination and capture functions.
Solution Approach 2:
The system transitions from a two-dimensional integration within the optical path to a three-dimensional arrangement where illuminator and camera are positioned externally and coupled through waveguides. This dimensional change allows the optical path to maintain its clarity for display while the illuminator and camera operate independently in external positions, eliminating path obstruction.
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
Simplifies integration and alignment of sensors by aligning only the optical path, reducing complexity and weight, and enabling customizable fitting for users.
Implementation Method 1
vectored into the optical path by at least one illuminator waveguide, such that the illuminator output is (similarly to the display image) projected along the optical path and reflected off the display surface into the user's eye
Implementation Method 2
vectored into the optical path by one or more imaging waveguides, such that the camera captures an image of the illuminated eye via the optical path, but in the opposite direction
Implementation Method 3
The generated image is projected along an optical path including one or more lenses, waveguides, and/or other optical elements for projecting the display image from the display source toward the display surface
Data Source
AI summary
A system and method for eye tracking via a head worn display (HWD), helmet mounted display (HMD) or other wearable display device provides an optical path of one or more optical elements for directing a display image into a display surface, which reflects the image into an eye location for viewing by a user or wearer of the display. An illuminator is optically coupled into the optical path via illuminator waveguides such that luminous output is vectored along the optical path, reflecting off the display surface and illuminating the wearer’s eye for imaging. Similarly, a camera is vectored into the same optical via imaging waveguides such that the camera may capture ocular images of the illuminated eye reflected off the display surface and directed via the optical path, but in the opposite direction. In this way the illuminator and camera may be incorporated into the optical path without obstructing it.