Ellipsoidal Lensing Structure for Eye Accommodation Measurement

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Solution Overview

Problem

Conventional methods for determining the accommodative state of the eye in head-mounted displays (HMDs) are inaccurate, especially across different age demographics, as they rely on Vergence-Accommodation Conflict (VAC) approximations rather than direct measurement, which varies with age and accommodative response.

Innovation Solution

An ellipsoidal lensing structure is used to capture and analyze the wavefront image of infrared light propagating through the eye lens, determining the accommodative state by measuring divergence or convergence, and adjusting virtual images presented to the user based on this measurement.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Device complexity

If conventional Vergence-Accommodation Conflict (VAC) approximation methods are used to determine eye focusing location, then the system can operate with simpler assumptions, but the measurement precision deteriorates significantly across different age demographics

Engineering Contradiction:

Improvesystem complexityVSAvoideye focusing location accuracy

Core Design Contradiction:

Device complexityVSMeasurement precision

Solution Approach 1:

The patent replaces the conventional Vergence-Accommodation Conflict approximation method with direct optical wavefront measurement using an ellipsoidal lensing structure. This substitution enables accurate measurement of accommodative state across all age groups by directly capturing the eye's optical response rather than relying on indirect behavioral approximations.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent introduces an ellipsoidal lensing structure as an intermediary component that captures wavefront information from the eye. This intermediary enables the system to indirectly measure the accommodative state through wavefront analysis, providing accurate data without requiring direct observation of eye muscle activity or behavioral responses.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Measurement precision

If direct wavefront measurement using ellipsoidal lensing structure is implemented, then measurement precision of accommodative state improves, but device complexity increases due to additional optical components

Engineering Contradiction:

Improveaccommodative state measurement accuracyVSAvoidoptical system complexity

Core Design Contradiction:

Measurement precisionVSDevice complexity

Solution Approach 1:

The ellipsoidal lensing structure serves multiple functions simultaneously: it captures wavefront information, focuses infrared light, and enables age-independent measurement of accommodative state. This multi-functionality reduces the need for separate specialized components, thereby limiting the increase in overall device complexity despite the advanced measurement capability.

Inventive Principle:

Principle #6Universality (Multi-functionality)

3Speed

If real-time wavefront imaging is implemented to capture accommodative response, then the speed of accommodative state determination improves, but the loss of time for image capture and processing increases

Engineering Contradiction:

Improveaccommodative state determination speedVSAvoidimage capture and processing time

Core Design Contradiction:

SpeedVSLoss of time

Solution Approach 1:

The system performs preliminary capture of wavefront information using the ellipsoidal lensing structure before final processing. By pre-acquiring the wavefront data and preparing it for analysis, the system reduces the time required for subsequent processing steps, enabling faster determination of accommodative state while maintaining real-time performance.

Inventive Principle:

Principle #10Preliminary action

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 approach allows for real-time or pseudo-real-time measurement of the accommodative state, improving accuracy across age demographics by directly measuring the eye's accommodative response rather than relying on approximations, enhancing the user's ability to focus on virtual images in HMDs.

Implementation Method 1

capture a wavefront image of infrared light propagating through the lens of an eye

Methodology Applied

Scientific EffectRefraction: Refraction

Implementation Method 2

An ellipsoidal lensing structure is used to capture and analyze the wavefront image of infrared light propagating through the eye lens

Methodology Applied

Scientific EffectFocusing: Focusing

Data Source

PatentUS10852551B1Wavefront sensing with ellipsoidal lensing structure

Publication Date: 2020.12.01 META PLATFORMS TECHNOLOGIES LLC

AI summary

An eye is illuminated with infrared illumination light. Illuminating the eye includes illuminating an ellipsoidal lensing structure with the infrared illumination light. A wavefront image of the reflected infrared light is generated. The reflected infrared light is the infrared illumination light reflected by a retina and exiting a pupil of the eye. The ellipsoidal lensing structure redirects the reflected infrared light to a wavefront sensor that generates the wavefront image. An accommodative eye state value is generated based at least in part on the wavefront image.