HMD Aberration Correction via Eye Tracking and Pre-Distortion
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Solution Overview
Problem
Conventional head-mounted displays (HMDs) fail to fully compensate for optical aberrations introduced by their optics, leading to distorted images for users due to lens imperfections, which vary with viewing angle and eye position.
Innovation Solution
An auto-focus HMD system that includes an eye tracking module, varifocal actuation block, and calibration store to dynamically generate aberration-adjusted images by determining the user's eye position and orientation, and applying pre-distortion to correct optical aberrations in real-time, ensuring minimal distortion when light passes through the optics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional HMDs use fixed optics to display images, then the device structure is simple, but optical aberrations and distortion occur due to lens imperfections that vary with viewing angle and eye position
Solution Approach 1:
The HMD employs a varifocal system that dynamically adjusts the focal length of the optics based on the user's eye position and accommodation state. The optics block can change its optical properties in real-time to compensate for aberrations, transforming from a static to a dynamic system that adapts to varying viewing conditions and eye positions
Solution Approach 2:
The system incorporates eye tracking that continuously monitors the user's eye position, orientation, and accommodation state. This feedback information is used to dynamically adjust the optics and pre-distort the image, creating a closed-loop control system that maintains optimal image quality across different viewing conditions
2Manufacturing precision
If the HMD uses a varifocal system to change optical depth, then image quality across different focal distances is improved, but the device complexity and mechanical components increase
Solution Approach 1:
The patent replaces traditional mechanical varifocal mechanisms with a computational approach. Instead of physically adjusting lens elements or moving components, the system uses software-based pre-distortion of the image and dynamic adjustment of optical parameters to achieve varifocal effects, eliminating complex mechanical parts while maintaining image quality
Solution Approach 2:
The system changes optical parameters such as focal length and aberration characteristics through software control of the optics block. By dynamically modifying these parameters based on eye tracking data, the system achieves multiple focal states without requiring physical reconfiguration of the optical path or additional mechanical components
3Manufacturing precision
If the HMD pre-distorts images for multiple viewing angles, then aberration correction is improved, but the rendering complexity and processing requirements increase
Solution Approach 1:
The system pre-calculates and stores distortion correction maps for various viewing angles and eye positions. Before displaying the image, the system determines the user's current eye position and retrieves or interpolates the appropriate pre-computed correction parameters, avoiding real-time complex calculations and enabling fast rendering
Solution Approach 2:
The system implements adaptive rendering that applies full aberration correction only for the current foveal region where the user is looking, while using simplified or interpolated corrections for peripheral regions. This partial correction approach maintains perceived image quality while reducing overall rendering complexity and processing requirements
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 effectively corrects optical aberrations for each user's eye position and viewing angle, providing clear, aberration-free images that mimic real-world vision, reducing the need for prescription corrections and enhancing the overall image quality in virtual environments.
Implementation Method 1
An auto-focus head-mounted display (HMD) dynamically generates aberration-adjusted images based on the position and/or orientation of user's eye(s)
Implementation Method 2
Lens imperfections of the optics block cause light from the electronic display to be distorted as the light passes through the optics block
Data Source
AI summary
An auto-focus head-mounted display (HMD) dynamically generates aberration-adjusted images based on the position and/or orientation of an eye of the user. An aberration-adjusted image is an image distorted to correct aberrations that would otherwise occur at a retina of the user due to image light passing through optics of the HMD that contains one or more optical imperfections. The aberration-adjusted image corrects the aberrations caused by these optical imperfections so that the resulting retinal image is free of optical aberrations due to the HMD while preserving correct eye optical aberrations that correlate with a current accommodative state of the eye.