Eye Tracking Illumination via Reflected Structured Light
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Solution Overview
Problem
Existing eye-tracking systems for artificial reality are not accurate, cost-effective, and power-efficient due to their reliance on peripheral light sources and cameras, which can obstruct the user's view and lead to errors in determining the gaze direction.
Innovation Solution
An eye-tracking system using an array of reflectors, such as hot mirrors, immersed in a transparent substrate positioned in front of the user's eyes, which reflect light for illumination and imaging, allowing for more precise and efficient eye tracking without obstructing the view, using a beam splitter to split the light beam into multiple beams for equal illumination and reducing light wastage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If peripheral light sources are used for eye illumination, then the eye can be illuminated for tracking, but the light sources and cameras obstruct the user's view and reduce immersion
Solution Approach 1:
The illumination system is segmented into multiple discrete light sources positioned at the periphery of the display field of view, with each light source corresponding to a specific region. This segmentation allows the light sources to be positioned at the edges rather than in the center, minimizing obstruction of the user's view while maintaining effective eye illumination for tracking.
Solution Approach 2:
The system transitions from a single centralized light source to multiple distributed light sources arranged in a two-dimensional array at the periphery of the field of view. This spatial redistribution moves the illumination function to the edges of the visual field, allowing the user to view content centrally without obstruction while still receiving adequate illumination for eye tracking.
2Device complexity
If a single large divergent light beam is used for illumination, then the light source is simple, but light energy is wasted in gaps between mirrors and illumination is uneven
Solution Approach 1:
The single divergent light beam is segmented into multiple discrete beams using a beam splitter, with each beam directed toward a specific mirror in the array. This segmentation ensures that light energy is concentrated on the mirrors rather than being wasted in gaps between them, improving overall illumination efficiency while maintaining relatively simple individual light source components.
Solution Approach 2:
Each light beam is locally directed to illuminate a specific mirror or region of the eye, creating non-uniform illumination patterns that are optimized for tracking accuracy. The beam splitter directs light energy to specific locations where it is needed most, rather than using uniform divergent illumination, thereby reducing energy waste while improving measurement precision.
3Measurement precision
If multiple light sources are used for illumination, then eye illumination can be improved, but power consumption increases
Solution Approach 1:
The illumination system uses multiple discrete light sources positioned at the periphery, each illuminating a specific region. By positioning light sources at the edges rather than using multiple intense sources at the center, the system achieves adequate illumination for tracking with lower overall power consumption, as each individual light source operates at reduced intensity.
Solution Approach 2:
A beam splitter acts as an intermediary component that distributes light from multiple sources efficiently to the eye. The beam splitter enables the system to use multiple light sources while maintaining low power consumption by optimizing light path efficiency and reducing redundant illumination, thereby improving gaze determination accuracy without proportionally increasing energy use.
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
The system provides accurate and efficient eye tracking with minimal light leakage and power consumption, allowing for improved user immersion in artificial reality environments by accurately determining the gaze direction without obstructing the user's view.
Implementation Method 1
a beam splitter configured to split the light beam emitted by the light source into a plurality of light beams
Implementation Method 2
a plurality of reflectors within the substrate. Each of the plurality of reflectors may be configured to intercept one or more light beams from the plurality of light beams, reflect light in the one or more light beams from the plurality of light beams to the eye of the user
Implementation Method 3
The substrate may be transparent to both light in the first wavelength range and light in the second wavelength range
Implementation Method 4
a camera configured to detect light in the first wavelength range
Data Source
AI summary
Disclosed herein are techniques for eye illumination for eye position tracking. An illumination system includes a light source configured to emit a light beam in a first wavelength range, a beam splitter configured to split the light beam emitted by the light source into a plurality of light beams, a substrate configured to be placed in front of an eye of a user, and a plurality of reflectors located within the substrate. Each of the plurality of reflectors is configured to intercept one or more light beams from the plurality of light beams, reflect light in the one or more light beams from the plurality of light beams to the eye of the user, and transmit light in a second wavelength range different from the first wavelength range to the eye of the user. The substrate is transparent to both light in the first wavelength range and light in the second wavelength range.