Holographic Eye-Tracking Illuminator With Parabolic Mirror Array
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Solution Overview
Problem
Conventional head-mounted display devices are limited by their size and weight, leading to reduced brightness and increased power consumption, and existing eye-tracking systems face challenges in providing in-field illumination without occluding the user's field of view, especially due to variations in eye relief, eyelid occlusions, and iris sizes.
Innovation Solution
An eye-tracking system utilizing a holographic illuminator with a light source and a holographic medium that projects multiple light patterns concurrently onto the eye, allowing for accurate pupil location determination without occluding the field of view, using a method that includes separating light into portions and transmitting them through different optical elements to form a holographic medium for in-field illumination.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If images are projected over a large area to provide wide field of view, then field of view is improved, but brightness of projected images deteriorates
Solution Approach 1:
The patent segments the projection area into multiple discrete zones corresponding to different gaze directions. Instead of projecting a single diffuse image over a large area, the system divides the field of view into segmented regions and projects focused images only to the relevant segment based on detected pupil position, thereby maintaining brightness while providing wide field of view capability.
Solution Approach 2:
The system dynamically adjusts the projection area and brightness distribution based on real-time eye tracking data. The projection target moves and resizes dynamically according to pupil position, allowing the system to concentrate light intensity on the active viewing area while maintaining the capability to serve wide field of view, thus resolving the contradiction between static large-area projection and dynamic brightness requirements.
2Illumination intensity
If a high intensity light source is used to compensate for reduced brightness, then brightness is improved, but device weight and power consumption deteriorate
Solution Approach 1:
The patent applies partial action by projecting light only to the necessary portion of the field of view based on detected pupil position, rather than illuminating the entire field. This partial illumination approach maintains adequate brightness in the relevant area while using a lower intensity light source, thereby reducing the weight and power consumption associated with high-intensity illumination systems.
Solution Approach 2:
The system uses the user's own eye movements and pupil position as feedback to automatically adjust the projection area and light distribution. This self-service mechanism eliminates the need for heavy mechanical adjustment mechanisms or high-power constant illumination, achieving efficient brightness control through intelligent light routing based on real-time ocular tracking.
3Area of stationary object
If illumination is positioned away from field of view to avoid occlusion, then field of view occlusion is reduced, but eye tracking accuracy deteriorates due to eye relief variations and eyelid occlusions
Solution Approach 1:
The patent transitions from two-dimensional planar illumination to three-dimensional volumetric light distribution using a lens array. Multiple lenses project light patterns from different spatial positions and angles, creating a three-dimensional illumination volume that can accommodate variations in eye relief and reduce the impact of eyelid occlusions, thereby maintaining tracking accuracy while preserving field of view.
Solution Approach 2:
The system dynamically changes illumination parameters including light position, angle, and intensity distribution based on detected eye position and pupil location. By adjusting these parameters in real-time, the system compensates for variations in eye relief and minimizes eyelid occlusion effects, maintaining measurement precision without requiring the illumination source to be positioned away from the field of view.
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 reliable pupil tracking with reduced occlusion, enabling compact, lightweight, and low-power head-mounted displays that can update content based on gaze direction, enhancing virtual and augmented reality experiences.
Implementation Method 1
a holographic medium configured to receive the light provided from the light source and project a plurality of separate light patterns concurrently toward an eye
Implementation Method 2
a detector configured to detect a reflection of at least a subset of the plurality of separate light patterns, reflected off the eye, for determining a location of a pupil of the eye
Data Source
AI summary
A system for making a holographic medium for use in generating light patterns for eye tracking includes a light source configured to provide light and a beam splitter configured to separate the light into a first portion of the light and a second portion of the light that is spatially separated from the first portion of the light. The system also includes a first set of optical elements configured to transmit the first portion of the light for providing a first wide-field beam onto an optically recordable medium, a second set of optical elements configured to transmit the second portion of the light for providing a second wide-field beam, and a plurality of parabolic reflectors optically coupled with the second set of optical elements and configured to receive the second wide-field beam and project a plurality of separate light patterns onto the optically recordable medium for forming the holographic medium.