Light Field Camera for Forearm Vein Authentication
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Solution Overview
Problem
Wearable electronic devices, such as smartwatches, face challenges in implementing bioauthentication due to limited space for sensors, with issues like arm hair interference and deep vein structures being difficult to image accurately from the dorsal side of the forearm.
Innovation Solution
Incorporating a light field camera that emits light into the forearm and captures remitted light using an array of micro-cameras with overlapping fields of view, performing synthetic focusing to construct images of different layers, allowing for feature extraction and comparison to authenticate users.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a conventional camera is used to image deep vein structures from the dorsal side of the forearm, then the imaging depth is limited, but the image resolution and accuracy deteriorate due to inability to focus on deep layers
Solution Approach 1:
The patent transitions from conventional 2D imaging to 3D light field imaging by capturing not only the intensity but also the directional information of light rays. This dimensional enhancement allows synthetic focusing at multiple depths within the forearm tissue, enabling accurate imaging of deep vein structures while maintaining a relatively simple camera form factor.
Solution Approach 2:
The light field camera performs preliminary capture of light field data containing information from multiple depths before any processing occurs. This preliminary action stores the directional and spatial information needed for subsequent synthetic focusing operations, allowing the system to reconstruct images at different depths without requiring physical adjustment of the camera or additional hardware.
2Measurement precision
If light is emitted through the cover into the dorsal side of the forearm to image deep structures, then imaging depth increases, but arm hair interference worsens the quality of captured images
Solution Approach 1:
The patent uses light field imaging as an intermediary technique that captures light rays from multiple angles and directions. This intermediary approach allows the system to distinguish between light scattered by arm hair and light originating from deep vein structures, effectively filtering out the harmful interference while maintaining imaging depth capability.
Solution Approach 2:
The light field camera captures light field data with directional information, enabling the system to apply different processing qualities to different spatial locations and depths. By analyzing the angular distribution of light rays, the system can selectively enhance signals from deep structures while suppressing contributions from superficial hair, achieving local quality optimization at different depths within the tissue.
3Reliability
If a light field camera with array of micro-cameras is used to overcome imaging limitations, then imaging capability improves, but the device space requirement increases
Solution Approach 1:
The light field camera is segmented into an array of micro-cameras, each capturing a portion of the light field from a specific angular perspective. This segmentation allows the system to achieve comprehensive light field coverage while keeping each individual micro-camera small and simple, thereby maintaining overall compactness suitable for wearable devices.
Solution Approach 2:
The patent merges multiple micro-camera units into a single integrated light field camera module. By combining the optical paths and image sensors of multiple micro-cameras into one cohesive system, the patent achieves enhanced bioauthentication capability without proportionally increasing the overall device footprint, as the micro-cameras share common structural and processing resources.
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 method enables effective bioauthentication by overcoming the limitations of arm hair interference and deep vein imaging, providing reliable user authentication and health monitoring capabilities.
Implementation Method 1
The light emitter is positioned to emit light through the cover into a dorsal side of a forearm near a wrist of a user when the first surface of the cover is positioned adjacent the dorsal side of the forearm near the wrist. The light field camera is positioned adjacent the second surface to receive remissions of the light through the cover from the dorsal side of the forearm near the wrist.
Data Source
AI summary
A method of authenticating a user of a wearable electronic device includes emitting light into a dorsal side of a forearm near a wrist of the user; receiving, using a light field camera, remissions of the light from the dorsal side of the forearm near the wrist of the user; generating a light field image from the remissions of the light; performing a synthetic focusing operation on the light field image to construct at least one image of at least one layer of the forearm near the wrist; extracting a set of features from the at least one image; determining whether the set of features matches a reference set of features; and authenticating the user based on the matching. In some embodiments, the method may further include compensating for a tilt of the light field camera prior to or while performing the synthetic focusing operation.