Holographic Illuminator Prism Array for HMD Eye Tracking
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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 face challenges in eye-tracking due to occlusion of the field-of-view and variations in eye anatomy.
Innovation Solution
An eye-tracking system using a holographic illuminator with a light source and a holographic medium that projects multiple light patterns onto the eye, allowing for in-field illumination without occluding the view, enabling accurate pupil location determination.
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 is reduced
Solution Approach 1:
The patent segments the projection area into multiple discrete light patterns (e.g., multiple spots or regions) that can be independently controlled. Instead of projecting light uniformly over a large area, the system divides the area into separate zones, each receiving concentrated light from the light source. This segmentation allows the light to be focused into specific regions, maintaining brightness while covering a wide overall field of view through the arrangement of multiple patterns.
2Illumination intensity
If a high intensity light source is used to compensate for reduced brightness, then brightness is improved, but device size and weight increase
Solution Approach 1:
By segmenting the light distribution into multiple focused patterns, the system achieves effective illumination with a lower intensity light source. The light is concentrated into specific regions rather than being diffused, which maintains brightness in each pattern while allowing the use of a smaller, lighter light source overall.
Solution Approach 2:
The patent applies local quality by creating specific light patterns with concentrated intensity at targeted locations rather than uniform illumination. Each light pattern has high local brightness where needed, while the overall system can use a less powerful light source because the light is efficiently directed to specific areas rather than being wasted across the entire field of view.
3Object-affected harmful factors
If light source 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 anatomy variations
Solution Approach 1:
The patent segments the illumination into multiple light patterns that can be strategically positioned within the field of view. Instead of using a single light source position, the system creates multiple illumination zones that collectively cover the necessary areas for eye tracking while maintaining an unobstructed central field of view. This segmentation allows the light to be distributed in a way that avoids occlusion while still providing sufficient reference points for accurate eye tracking.
Solution Approach 2:
The light patterns serve multiple functions: they illuminate the field of view for the user while simultaneously providing reference points for eye tracking. The same optical system that provides the user's view also creates the illumination patterns needed for tracking, eliminating the need for separate light source positioning and accommodating various eye anatomies through the flexible pattern design.
4Adaptability or versatility
If conventional eye tracking illumination is used, then eye tracking is achieved, but device complexity increases to accommodate various eye anatomies
Solution Approach 1:
The patent uses segmented light patterns that can be independently adjusted to accommodate different eye anatomies. By dividing the illumination into multiple patterns, the system can selectively modify individual patterns to match variations in pupil size, eye shape, and anatomical differences among users, providing adaptability without requiring a completely reconfigurable system.
Solution Approach 2:
The system accommodates various eye anatomies by changing parameters of the light patterns, such as size, intensity, and position of each pattern. Rather than physically reconfiguring the optical system, the patent adjusts the characteristics of the light patterns to match different eye structures, providing versatility through software-controlled parameter modification rather than hardware complexity.
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 compact, low-power head-mounted displays with accurate eye-tracking, enhancing virtual and augmented reality experiences by reducing occlusion and accommodating various eye anatomies.
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
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 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 prisms 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.