Holographic Waveguide Optical Tracker for Eye Tracking
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current eye trackers face challenges in achieving a compact, lightweight, transparent design with low latency and a wide field of view, particularly in eye-slaved displays and LIDAR systems, due to limitations in optical design and processing latency.
Innovation Solution
The development of an object tracker using a waveguide with switchable Bragg gratings that deflects illumination and image light through separate optical paths, allowing for efficient tracking of object motion with low latency and wide field of view, integrated with an image processing system for spatio-temporal characteristic determination.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If flat beam splitters and large optics are used to image reflections onto an imaging sensor, then the tracker can function, but the exit pupil is limited and the design becomes bulky
Solution Approach 1:
The patent replaces traditional mechanical optical components (flat beam splitters, large lenses, and mirrors) with a waveguide-based system that uses diffraction gratings to steer and focus light. This substitution enables compact integration while maintaining the optical functionality needed for accurate eye tracking, directly resolving the contradiction between tracking accuracy and device size.
2Ease of operation
If the imaging optics are positioned close to the beamsplitter to maximize exit pupil, then the exit pupil increases, but vision obscuration and safety hazards increase
Solution Approach 1:
The patent transitions from a two-dimensional arrangement where optics are positioned close to the beamsplitter to a three-dimensional waveguide structure where light propagation occurs within the bulk of the waveguide material. This dimensional change allows the exit pupil to be maximized while keeping the optical path separated from the user's direct line of sight, eliminating vision obscuration and safety hazards.
3Measurement precision
If large angular separation between illumination and detection optical axes is used, then corneal reflections can be tracked, but the field of view is limited
Solution Approach 1:
The patent employs dynamically switchable diffraction gratings that can change their diffraction patterns in response to eye movement. This dynamic adaptation allows the system to maintain optimal angular separation for corneal reflection tracking while simultaneously adjusting the field of view to accommodate different gaze directions, resolving the contradiction between tracking precision and field of view.
4Volume of moving object
If direct imaging by miniature cameras is used, then the tracker becomes more compact, but processing latency increases due to feature recognition requirements
Solution Approach 1:
The patent extracts the feature recognition and processing burden from the imaging system by using a waveguide with diffraction gratings that optically separate and direct different light paths (illumination and detection) to their respective destinations. This extraction eliminates the need for complex real-time image processing, reducing latency while maintaining compact form factor.
5Adaptability or versatility
If the tracker is made transparent, then it can be integrated with displays, but the optical design becomes more complex
Solution Approach 1:
The patent implements a universal waveguide platform that simultaneously provides display functionality and eye tracking capability through integrated diffraction gratings. The same waveguide structure serves multiple functions: guiding display light to the user's eye, guiding illumination light to the eye, and guiding reflected light from the eye to the detector. This multi-functionality enables transparent display integration while managing optical design complexity through unified architecture.
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 enables a compact, lightweight, and transparent eye tracker with low latency and wide field of view, capable of delivering robust depth and occlusion cues, suitable for eye-slaved displays and LIDAR systems, by effectively managing illumination and image light paths within the waveguide.
Implementation Method 1
at least one grating lamina formed within said waveguide. The illumination light propagates along a first optical path from the source to an object. Image light reflected from at least one surface of an object is deflected by the grating lamina into a second optical path towards the detector.
Implementation Method 2
The illumination light propagates along a first optical path from the source to an object. Image light reflected from at least one surface of an object is deflected by the grating lamina into a second optical path towards the detector.
Data Source
AI summary
There is provided an object tracker having: a first waveguide; a source of illumination light; a detector optically coupled to the waveguide; and at least one grating lamina formed within the waveguide. Illumination light propagating along a first optical path from the source to an object in relative motion to the object tracker. Image light reflected from at least one surface of an object is deflected by the grating lamina into a second optical path towards the detector.