Internal Eye Illumination for Biometric Pupil Tracking

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Solution Overview

Problem

Existing biometric monitoring systems face challenges in simultaneously and continuously tracking pupil size and location, respiratory, and heart rate dynamics without intrusive equipment, and they struggle to differentiate between pupillary responses caused by arousal changes and those caused by ambient light fluctuations.

Innovation Solution

A system utilizing internal illumination of the back of the eye with infrared light sources and sensors positioned outside the head to record light exiting the eye, allowing for real-time, continuous measurement of biometric indicators such as pupil size, heart rate, and breathing rate, while minimizing equipment bulk and interference.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If external infrared illumination and camera are used to measure pupil size, then pupil size can be measured non-invasively, but the equipment is bulky and occludes the field of view, preventing natural behavior

Engineering Contradiction:

Improvepupil size measurementVSAvoidequipment bulk

Core Design Contradiction:

Measurement precisionVSDevice complexity

Solution Approach 1:

Instead of illuminating the eye from the front with external infrared light, the patent places the infrared light source inside the subject's head to illuminate the eye from behind. This inversion of the illumination direction eliminates the need for bulky external equipment while maintaining non-invasive measurement capability.

Inventive Principle:

Principle #13The other way round (Inversion)

Solution Approach 2:

The patent integrates multiple functions into a single internal device: the infrared light source provides illumination, the sensor detects light transmitted through the eye, and the processor analyzes pupil size. This multi-functionality consolidates what would traditionally require separate external components into one compact internal unit.

Inventive Principle:

Principle #6Universality (Multi-functionality)

2Measurement precision

If camera-based systems are used to capture pupil videos, then pupil size can be tracked, but the sampling rate is limited to 100 fps or below, preventing capture of high speed physiological events

Engineering Contradiction:

Improvepupil size trackingVSAvoidsampling rate

Core Design Contradiction:

Measurement precisionVSSpeed

Solution Approach 1:

The patent replaces the mechanical camera-based video capture system with an optical transmission measurement system. Instead of capturing images and processing them through segmentation algorithms, the system directly measures light transmission through the pupil, enabling much higher sampling rates suitable for capturing fast physiological events.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

3Measurement precision

If infrared emitters and sensors are placed in front of the eyes to replace camera, then pupillometry can be performed, but the system cannot segregate pupillary responses from arousal changes from those caused by ambient light fluctuations

Engineering Contradiction:

Improvepupillary response measurementVSAvoidsegregation of response types

Core Design Contradiction:

Measurement precisionVSLoss of information

Solution Approach 1:

By inverting the illumination direction to shine light from behind the eye rather than from the front, the system creates a measurement geometry where ambient light does not directly interfere with the detection. The sensor measures light transmitted through the pupil from the internal source, allowing clear separation of pupillary responses from ambient light effects.

Inventive Principle:

Principle #13The other way round (Inversion)

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 enables non-invasive, real-time monitoring of multiple biometric indicators with high sampling speeds, effectively distinguishing between arousal-related and ambient light-related pupillary responses, thus improving the accuracy and comfort of biometric data collection.

Implementation Method 1

The at least one light source comprises an infrared light source

Methodology Applied

Scientific EffectInfrared radiation: Infrared Radiation

Implementation Method 2

at least one light source configured for illuminating an eye of a subject using light from within a head of the subject

Methodology Applied

Scientific EffectLight transmission through tissue: Absorption (EM radiation)

Data Source

PatentUS20250025040A1Methods, systems, and computer readable media for biometric ocular photometry

Publication Date: 2025.01.23 THE UNIV OF NORTH CAROLINA AT CHAPEL HILL

AI summary

A system for determining a physical characteristic or measuring a physical activity of a subject using back-illumination of an eye of a subject includes at least one light source configured for illuminating an eye of a subject using light from within the head of the subject. The system further includes at least one light sensor positionable outside of the head of the subject for sensing light from the at least one light source exiting the subject through the eye of the subject. The system further includes a controller coupled to the at least one light source and to the at least one light sensor for recording an indication of the light while controlling the illuminating.