Multi-Path Eye Imaging for Robust Gaze and Refraction Capture
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Solution Overview
Problem
Existing eye metric acquisition devices face inefficiencies and robustness issues due to optical disturbances, particularly with users wearing glasses and large gaze angles, which affect accurate gaze vector detection and refractive error measurement.
Innovation Solution
The device employs multiple light paths with different angles to capture overlapping representations of the eye using mirrors, allowing for robust metric acquisition and gaze angle determination without a glint, and enables simultaneous visible spectrum stimulation and infrared eye tracking.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
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 reflections
Solution Approach 1:
The patent divides the single light path into multiple light paths (at least first and second light paths) that travel at different angles relative to the camera's optical axis. Each light path provides a separate representation of the eye, allowing the system to overcome optical disturbances by having redundant measurement channels. This segmentation resolves the contradiction by maintaining relatively simple device architecture while significantly improving measurement precision through multi-path illumination.
Solution Approach 2:
The patent introduces angular diversity by arranging light paths at different angles relative to the optical axis, adding a dimensional aspect to the illumination geometry. This angular dimension allows the system to capture eye metrics from multiple perspectives simultaneously, improving measurement precision without substantially increasing device complexity.
2Manufacturing precision
If the focus depth is increased to capture clear images, then the image quality is improved, but the productivity deteriorates due to slower image capturing speed
Solution Approach 1:
By segmenting the illumination into multiple light paths with different angles, the patent creates multiple imaging opportunities within the same exposure timeframe. This allows the system to use smaller focus depth with faster capture rates while still obtaining sufficient image quality through the combined information from multiple angled light paths.
Solution Approach 2:
The patent changes the illumination parameters by using multiple light paths at different angles, which effectively compensates for the reduced focus depth. This parameter change allows the system to achieve both fast capture rates and adequate image quality by relying on angular diversity rather than relying solely on deep focus.
3Device complexity
If a central light source close to the optical axis is used, then the device complexity is reduced, but the measurement precision deteriorates when the user wears glasses or has large gaze angles
Solution Approach 1:
Instead of using a single central light source, the patent segments the illumination into multiple light paths at different angles. This segmentation provides multiple representations of the eye in a single image, allowing the system to overcome the limitations of central illumination when users wear glasses or have large gaze angles, while maintaining relatively simple device architecture.
Solution Approach 2:
The patent creates multiple optical copies or representations of the eye by using multiple light paths at different angles. These multiple representations provide redundant information that compensates for optical disturbances caused by glasses or extreme gaze angles, improving measurement precision without substantially increasing device complexity.
4Measurement precision
If multiple mirrors are used to create multiple light paths, then the measurement precision is improved, but the device complexity increases
Solution Approach 1:
The patent uses multiple mirrors to segment the illumination into different light paths, each providing a separate representation of the eye. This segmentation improves measurement precision by providing redundant measurement channels that are resistant to optical disturbances, while the mirrors are arranged in a configuration that manages the increase in device complexity.
Solution Approach 2:
The multiple mirrors serve multiple functions: they create separate light paths for improved measurement precision, they can be arranged to compensate for focus depth limitations, and they enable the system to handle various user conditions (glasses, large gaze angles). This multi-functionality justifies the increased device complexity by delivering comprehensive measurement capabilities.
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, allowing for reliable gaze angle detection and refractive error measurement even with glasses and large gaze angles, while enabling faster image capturing and 3D content display.
Implementation Method 1
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
Data Source
Figure 1~3
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Figure 6~7
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, so 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.