Multi-Angle Eye Metric Acquisition for Robust Gaze and Refraction
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Solution Overview
Problem
Existing eye metric acquisition devices face inefficiencies and robustness issues due to optical disturbances, such as gaze angles and glasses, which complicate the detection of eye movements and refractive errors.
Innovation Solution
The device employs multiple light paths with different angles to capture overlapping representations of the eye, allowing for robust metric acquisition and gaze angle determination, even without a glint, using a combination of mirrors and dichroic filters to enable eye tracking and autorefraction, while allowing for 3D content display and reduced focus depth.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a single light path is used for eye metric acquisition, then the device complexity is reduced, but the measurement precision deteriorates due to optical disturbances such as large gaze angles and glasses
Solution Approach 1:
The system divides the single light path into multiple separate light paths (first light path via first mirror, second light path via second mirror) that capture the eye from different angles. This segmentation allows the system to obtain multiple representations of the eye, where at least one representation remains undistorted even when optical disturbances occur, thereby improving measurement precision without requiring an overly complex unified system
Solution Approach 2:
The invention introduces angular dimensionality by capturing eye images through multiple light paths at different angles relative to the camera's optical axis. This multi-dimensional approach ensures that when the eye moves or glasses cause distortion in one viewing angle, other angular perspectives provide valid measurement data, improving robustness while maintaining manageable device complexity
2Productivity
If a large camera aperture is used to reduce focus depth, then the productivity is improved through faster image capturing, but the manufacturing precision deteriorates due to reduced focus depth
Solution Approach 1:
The system segments the light paths with different lengths (first light path and second light path with length difference exceeding 1 of the shortest length), allowing the camera to have a smaller focus depth while ensuring that at least one light path maintains the eye within the focus depth. This enables faster image capturing with a larger aperture without sacrificing measurement quality
Solution Approach 2:
The invention changes the optical path length parameter by introducing mirrors at different positions and angles, creating light paths with deliberately different lengths. This parameter variation ensures that temporal focusing effects benefit different light paths differently, allowing the system to use a smaller focus depth for faster capture while maintaining measurement accuracy through the diversity of path lengths
3Reliability
If multiple mirrors are used to provide separate light paths, then the reliability is improved through robust capturing, but the device complexity increases
Solution Approach 1:
The system uses multiple mirrors (first mirror, second mirror, and potentially additional mirrors) to segment the light paths, with each mirror providing a separate optical path that pictures an overlapping portion of the acquisition space. This segmentation creates redundant capture paths, improving reliability through multiple independent views of the eye while keeping each individual mirror simple in structure
Solution Approach 2:
The mirrors serve multiple functions: they redirect light from different angles to the camera, create overlapping representations of the eye, and can be positioned on a concave surface to maintain compact device geometry. This multi-functionality allows the system to achieve high reliability through multiple light paths without proportionally increasing device complexity
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
This approach enhances the robustness and accuracy of eye metric acquisition, enabling effective eye tracking and refractive error determination, even with glasses or large gaze angles, and allows for faster image capturing and 3D effects.
Implementation Method 1
the camera is configured to receive light from the acquisition space via at least first and second light paths, at different angles with respect to the optical axis of the camera. Light of at least the first light path is received via a first mirror
Implementation Method 2
A dichroic filter mirror may be located between the acquisition space and the first mirror. This allows the system to display stimuli to the eyes in the visible spectrum, while e.g. carrying out eye tracking in the infrared spectrum
Data Source
AI summary
The present disclosure relates to a method and a device for acquisition of a metric of an eye (1) located in an acquisition space (29). The device comprises at least one light source (11) configured to emit light towards the acquisition space, a camera (15) configured to receive light from the acquisition space to (29) generate image data, and an analyzing unit (14) configured to extract at least one metric from the image data. The camera (15) is configured to receive light from the acquisition space via at least two light paths (17, 19) which are differently angled with respect to the optical axis of the camera, the light of at least one path being received via a first mirror (21). The camera receives light from an overlapping portion of the acquisition space via the first and second paths, as to allow the camera to receive at least two representations of a single eye. This metric may be used for e.g. eye tracking or autorefraction/accomodation.