Dual-Wavelength Eye Imaging for Accurate Gaze Direction

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Solution Overview

Problem

Existing eye imaging systems require extensive calibration and have limitations in speed and accuracy, particularly in determining eye position and gaze direction.

Innovation Solution

A near-eye imaging system using dual near-infrared wavelengths with separate filters and illuminators, combined with holographic optical elements, captures stereo images to enhance accuracy and reduce calibration needs.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If single wavelength imaging is used, then device complexity is reduced, but measurement precision deteriorates

Engineering Contradiction:

Improveeye imaging accuracyVSAvoiddual wavelength system complexity

Core Design Contradiction:

Measurement precisionVSDevice complexity

Solution Approach 1:

The imaging system is segmented into two separate imaging channels, each dedicated to a specific wavelength (850nm and 940nm). Each channel includes dedicated illuminators, optical combiners, and camera sensors with wavelength-specific filters. This segmentation allows independent optimization of each wavelength channel for maximum measurement precision while maintaining manageable system complexity through modular architecture.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The near-eye optical element serves multiple functions: it acts as a beam splitter for visible light, an optical combiner for infrared wavelengths, and integrates both illumination and imaging functions. The optical combiner specifically directs both 850nm and 940nm infrared wavelengths to their respective camera sensors while remaining transparent to visible light, enabling multi-wavelength imaging without requiring separate optical paths.

Inventive Principle:

Principle #6Universality (Multi-functionality)

2Measurement precision

If extensive calibration is performed, then measurement precision improves, but loss of time increases

Engineering Contradiction:

Improveeye position accuracyVSAvoidcalibration time

Core Design Contradiction:

Measurement precisionVSLoss of time

Solution Approach 1:

The dual wavelength system performs self-calibration by capturing images at two different wavelengths and automatically processing these images to determine eye position and gaze direction. The system uses the complementary information from both wavelengths to inherently correct for optical aberrations and geometric distortions, eliminating the need for manual calibration procedures and reducing calibration time to minimal initial setup.

Inventive Principle:

Principle #25Self-service

3Measurement precision

If dual wavelength imaging is implemented, then measurement precision improves, but device complexity increases

Engineering Contradiction:

Improvegaze direction accuracyVSAvoidfilter and illuminator complexity

Core Design Contradiction:

Measurement precisionVSDevice complexity

Solution Approach 1:

The system merges the illumination and imaging functions into a single integrated near-eye optical element. Both 850nm and 940nm illuminators are combined in the same optical path, with corresponding wavelength-specific optical combiners and camera sensors. The optical combiner merges the visible light path with the infrared imaging paths, allowing compact integration of multiple functions without proportionally increasing device complexity.

Inventive Principle:

Principle #5Merging (Combining)

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

Improves eye imaging accuracy, particularly in the z-dimension, reducing gaze direction determination errors by a factor of three or more and minimizing calibration complexity.

Implementation Method 1

at least one of the first combiner layer and the second combiner layer may include a holographic optical element (HOE)

Methodology Applied

Scientific EffectHolographic optical element:

Implementation Method 2

the first combiner layer may selectively direct the first near-infrared light incident at a first angle to the camera module, and wherein the second combiner layer selectively directs the second near-infrared light incident at a second angle to the camera module

Methodology Applied

Scientific EffectLight diffraction: Diffraction

Implementation Method 3

the camera module may include: first filters overlaying first pixels of the camera module, wherein the first filters pass the first near-infrared light and reject other light, the first ocular image generated by the first pixels; and second filters overlaying second pixels of the camera module, wherein the second filters pass the second near-infrared light and reject other light

Methodology Applied

Scientific EffectOptical filtering: Filter (optical)

Implementation Method 4

the first illuminators and the second illuminators may include at least one of a micro light emitting diode (micro-LED), an edge emitting LED, a vertical cavity surface emitting laser (VCSEL) diode, or a Superluminescent diode (SLED)

Methodology Applied

Scientific EffectLight emitting diode: Light Emitting Diode

Implementation Method 5

Methodology Applied

Scientific EffectLaser emission: Laser

Data Source

PatentEP4107571B1Dual wavelength eye imaging

Publication Date: 2025.09.24 META PLATFORMS TECHNOLOGIES LLC

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AI summary

An eye is illuminated with a first non-visible light wavelength and a second non-visible light wavelength. A first ocular image is captured from first reflected light having the first non-visible light wavelength and a second ocular image is captured from second reflected light having the second non-visible light wavelength.