Adjustable Illumination Pattern for Eye Tracking Stray Light
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Solution Overview
Problem
Existing head-mounted eye trackers face challenges in accurately distinguishing eye movement features from environmental stray light, leading to limited accuracy and robustness, and require complex calibration procedures due to individual eye characteristics like corneal astigmatism.
Innovation Solution
An optical measuring device with an adjustable illumination unit that creates a well-defined illumination pattern, using a lock-in technique to suppress background and stray light, allowing the capturing unit to differentiate between deliberate reflections and environmental reflections, thereby eliminating the need for extensive calibration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional illumination is used in head-mounted eye trackers, then the device can operate in various environmental conditions, but environmental stray light cannot be distinguished from eye movement features, reducing detection accuracy
Solution Approach 1:
The illumination unit emits light in a periodic manner with specific temporal patterns that are encoded into the illumination characteristic. This periodic illumination allows the capturing unit to distinguish between deliberate eye reflections and environmental stray light by detecting the temporal modulation pattern, thereby resolving the contradiction between detection accuracy and environmental interference.
Solution Approach 2:
The illumination characteristic is made adjustable with respect to temporal illumination sequences and spatial illumination distributions. By changing these parameters dynamically, the system creates a well-defined illumination pattern that can be differentiated from environmental light, improving detection accuracy while maintaining operational flexibility in various conditions.
2Measurement precision
If extensive calibration procedures are implemented to account for individual eye characteristics, then measurement precision improves, but device complexity and time consumption increase
Solution Approach 1:
The system uses the adjustable illumination unit to create a well-defined illumination pattern that automatically accounts for individual eye characteristics such as corneal astigmatism. The capturing unit detects reflections from this controlled illumination, eliminating the need for separate calibration procedures while maintaining high measurement precision for each user.
Solution Approach 2:
The illumination unit is configured to emit light with specific temporal and spatial patterns before actual eye tracking measurements are taken. This preliminary structured illumination establishes a known reference pattern that simplifies subsequent detection and eliminates the need for complex calibration routines, as the system already accounts for individual eye characteristics through the controlled illumination itself.
3Measurement precision
If the illumination unit emits light to create reflections on the eye, then the capturing unit can detect eye features more accurately, but the illumination may cause discomfort or safety concerns
Solution Approach 1:
The illumination unit operates in a periodic manner with controlled temporal patterns, emitting light only when needed for measurement. This periodic operation reduces overall light exposure to safe levels while maintaining sufficient illumination for accurate eye feature detection, balancing measurement precision with user comfort and safety.
Solution Approach 2:
The illumination characteristic is adjustable with respect to intensity, temporal sequence, and spatial distribution. The system can optimize these parameters to create sufficient reflections for accurate detection while keeping the overall illumination level comfortable and safe for the user, allowing flexible adaptation to different operating conditions.
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 solution significantly enhances detection accuracy and robustness by creating a recognizable illumination pattern that distinguishes between intended and unintended light reflections, improving eye tracking capabilities and integrating astigmatism assessment directly into the device.
Implementation Method 1
an illumination unit for illuminating the at least one eye
Implementation Method 2
The capturing unit is configured to optically capture the at least one parameter of the at least one eye... deliberate reflections on the test person's eyes can be created, which may then be captured by the capturing unit
Implementation Method 3
an array of sensors on the frame for detecting light from the array of emitters. The sensors detect light that is reflected off of respective portions of the eye
Data Source
AI summary
The invention relates to an optical measuring device (1) for capturing at least one parameter of at least one eye (10l, 10r) of a test person (31) wearing the optical measuring device (1), comprising a frame (4), which is configured to fix the optical measuring device (1) to the head of the test person (31), at least one capturing unit (3l, 3r), which is configured to optically capture the at least one parameter of the at least one eye (10l, 10r), and an illumination unit (9, 21, 22) for illuminating the at least one eye (10l, 10r), wherein an illumination characteristic is adjustable by means of the illumination unit (9, 21, 22).