3D Eye Model Geometry for Six-Degree Eye Tracker Calibration
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Solution Overview
Problem
Current eye tracking systems, used in refractive laser treatments, cannot adequately simulate all degrees of freedom of eye movement during test measurements, particularly translations along and rotations about the optical axis, due to the limitations of sheet- or plate-shaped test objects.
Innovation Solution
A three-dimensional eye model is developed, featuring a convexly curved peripheral surface and a cylindrical lateral surface, made of white polyvinyl chloride or similar materials, which includes a simulation of the sclera, pupil, and iris, allowing for accurate detection of eye movements in multiple dimensions using an infrared camera.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If sheet- or plate-shaped test objects are used for eye tracker calibration, then the device complexity is reduced and ease of manufacture is improved, but the ability to simulate all degrees of freedom of eye movement (particularly translations along and rotations about the optical axis) is insufficient
Solution Approach 1:
The patent transitions from two-dimensional sheet- or plate-shaped test objects to a three-dimensional eye model with a convexly curved peripheral surface. This dimensional change enables the test object to simulate translations along the optical axis and rotations about the optical axis, thereby achieving all six degrees of freedom of eye movement while maintaining manageable structural complexity through the use of a spherical coordinate system for defining surface points.
2Measurement precision
If sheet- or plate-shaped test objects with imprinted eye structures are used, then the manufacturing process is simplified, but the measurement precision for detecting eye movements in multiple dimensions is insufficient
Solution Approach 1:
By defining the peripheral surface using a spherical coordinate system with radius r, polar angle θ, and azimuthal angle φ, the patent enables accurate representation of three-dimensional eye movements including translations along the optical axis and rotations about the optical axis. This mathematical approach allows for precise measurement of all six degrees of freedom while keeping the manufacturing process relatively simple through standardized spherical geometry.
3Adaptability or versatility
If a three-dimensional eye model with convexly curved peripheral surface is implemented, then the ability to simulate eye movements in multiple dimensions is improved, but the device complexity and manufacturing difficulty increase
Solution Approach 1:
The patent employs a convexly curved peripheral surface defined by a spherical coordinate system, which naturally accommodates three-dimensional eye movements. The spherical geometry provides a mathematically elegant and manufacturing-friendly approach to creating a test object that can simulate all six degrees of freedom of eye movement, including translations along and rotations about the optical axis, without requiring complex asymmetric shapes.
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 eye model enables the simulation of translational and rotational movements of a human eye, allowing for comprehensive calibration and functionality testing of eye trackers, ensuring accurate detection and quantification of eye movements in refractive laser treatments.
Implementation Method 1
an infrared camera (54) for recording a plurality of infrared images of the eye model (10)
Data Source
Figure 1A~1D
Figure 2A~2B
Figure 3
AI summary
An eye model comprises a sclera simulation which is made of a bright plastic material, the plastic material containing a polyvinyl chloride at least as the main component, and a pattern which contrasts in color with the sclera simulation, the pattern simulating an eye pupil and/or an iris structure. In a method for producing the eye model, a plate-shaped or rectangular blank of the plastic material having two oppositely situated blank flat sides is used, from which an eye body is separated by cutting or chipping machining. The separated eye body has a flattened area which is formed from a first of the blank flat sides, and a convexly curved peripheral surface which surrounds the flattened area in a ring-like manner. The method also comprises forming the pattern on an area on the first blank flat side which corresponds to the first flattened area.