Interferometric Eye Tracker for Laser Treatment

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Solution Overview

Problem

Current eye tracking technologies for laser eye treatments are limited by their speed and accuracy due to reliance on two-dimensional camera-based systems, which can lead to suboptimal treatment results due to inaccuracies in tracking eye movements in three-dimensional space and are affected by ambient lighting.

Innovation Solution

A device using interferometric image acquisition based on three-dimensional optical coherence tomography for time-resolved detection of eye movements, providing high-speed and precise tracking of six-dimensional eye movements without interference from ambient lighting, allowing for precise alignment of treatment laser radiation.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If two-dimensional camera-based eye tracking is used, then the device complexity is reduced and ease of operation is improved, but measurement precision and tracking accuracy deteriorate due to inability to capture three-dimensional eye movements

Engineering Contradiction:
Improveeye movement tracking accuracyVSAvoideye tracker system complexity
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

The patent replaces camera-based optical detection with interferometric detection using optical coherence tomography. This substitution enables three-dimensional eye movement tracking with higher precision by detecting phase changes in interferometric signals, achieving six-dimensional tracking (three translational and three rotational movements) without the limitations of two-dimensional camera systems.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent transitions from two-dimensional camera imaging to three-dimensional interferometric detection. By using optical coherence tomography, the system captures depth information and three-dimensional structural data of the eye, enabling accurate tracking of eye movements in three-dimensional space including translational and rotational components.

Inventive Principle:
Principle #17Another dimension (Dimensionality change)

2Productivity

If camera-based eye tracking systems are used, then the device structure is simplified, but productivity is reduced due to limited frame rate that is too slow for real-time laser treatment correction

Engineering Contradiction:
Improveeye movement detection speedVSAvoideye tracker system complexity
Core Design Contradiction:
ProductivityVSDevice complexity

Solution Approach 1:

The patent replaces camera-based detection with interferometric detection using optical coherence tomography. This substitution enables high-speed eye movement tracking by detecting phase changes in interferometric signals, achieving frame rates suitable for real-time laser treatment correction without the speed limitations of camera-based systems.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

3Measurement precision

If ambient lighting is used to illuminate the eye for camera-based tracking, then ease of operation is improved, but measurement precision deteriorates due to interference from secondary lighting and scattering light

Engineering Contradiction:
Improveeye movement detection accuracyVSAvoidlighting requirements
Core Design Contradiction:
Measurement precisionVSUse of energy by moving object

Solution Approach 1:

The patent replaces camera-based optical detection with interferometric detection using optical coherence tomography. This substitution eliminates the problem of ambient light interference because the interferometric method detects phase changes in coherent light signals rather than relying on scattered or reflected ambient light, enabling accurate eye tracking independent of lighting conditions.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

4Measurement precision

If pupil center tracking is used, then the tracking system is simple to operate, but measurement precision deteriorates when pupil center deviates from the optical visual axis due to asymmetrical displacement

Engineering Contradiction:
Improvepupil tracking accuracyVSAvoidtracking method simplicity
Core Design Contradiction:
Measurement precisionVSEase of operation

Solution Approach 1:

The patent transitions from two-dimensional pupil center tracking to three-dimensional interferometric detection. By using optical coherence tomography, the system can identify anatomical landmarks and track eye movements in three-dimensional space, providing accurate measurement even when the pupil center deviates from the optical visual axis due to asymmetrical displacement or other conditions.

Inventive Principle:
Principle #17Another dimension (Dimensionality change)

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

Enables significantly higher measurement accuracy and speed for eye movement tracking, allowing for precise orientation and treatment of the eye, independent of lighting conditions and reducing the risk of suboptimal treatment outcomes.

Implementation Method 1

an eye tracker (12) for detecting eye movements and for outputting a signal representative of the detected eye movements, the eye tracker for the time-resolved detection of sectional images of the eye equipped interferometric image acquisition device

Methodology Applied
Scientific EffectInterference: Interference

Implementation Method 2

interferometric image acquisition device, which works on the basis of three-dimensional optical coherence tomography

Methodology Applied
Scientific EffectOptical coherence tomography: Tomography

Data Source

PatentEP2709577B1Device for examining or treating a human eye
Publication Date: 2017.06.21 WAVELIGHT AG
  • EP2709577B1 patent drawingFigure 1
  • EP2709577B1 patent drawingFigure 2~3
  • EP2709577B1 patent drawingFigure 4a~4b

AI summary

A device is proposed for examining or treating a human eye, with an eye tracker for detecting eye movements and for emitting a signal representative of the detected eye movements, wherein the eye tracker comprises an interferometric image detector, which is configured for the temporally resolved detection of sectional images of the eye and works on the basis of two-dimensional or three-dimensional optical coherence tomography, and also an evaluation module, which determines the eye movements solely from the sectional images.