Laser Corneal Eye Tracking with Self-Mixing Interferometry
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Solution Overview
Problem
Current eye tracking systems are high in power consumption, lack accuracy, and obstruct the field of view due to sensor placement, failing to provide a compact and efficient solution for augmented reality applications.
Innovation Solution
An eye tracking device using laser beams to measure corneal points, determining eye rotation without imaging, employing self-mixing interferometry for accurate distance and velocity measurements with a minimal number of laser beams.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If imaging sensors are used for eye tracking, then eye rotation can be determined, but power consumption increases and accuracy decreases
Solution Approach 1:
The patent replaces the mechanical/imaging-based eye tracking system with an optical interferometry system. Instead of using imaging sensors to capture and process images of the eye, the invention uses laser beams and interferometric detection to measure corneal surface displacement, thereby determining eye rotation. This substitution of the measurement principle achieves both higher accuracy and lower power consumption.
2Measurement precision
If imaging sensors are placed to maximize data quality, then tracking accuracy improves, but field of view is obstructed
Solution Approach 1:
The patent extracts the measurement function from the imaging path, allowing the laser output unit and receiver unit to be positioned independently of the user's field of view. The interferometric measurement system detects eye rotation through optical path changes rather than requiring direct imaging of the eye, thereby eliminating the need to place sensors in the visual path.
3Measurement precision
If multiple laser beams are used to improve accuracy, then measurement precision increases, but device complexity increases
Solution Approach 1:
The patent makes the laser output unit multi-functional by enabling it to emit multiple laser beams that serve different measurement purposes simultaneously. The same laser unit generates beams at different wavelengths or directions, allowing differential measurement of corneal surface features while maintaining a compact integrated design rather than requiring separate measurement systems.
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 offers low power consumption, high accuracy, and a small form factor, enabling unobtrusive eye tracking in AR devices.
Implementation Method 1
The receiver unit (which may be the same as the laser output unit when using SMI) is configured to receive a reflection of the laser beam and to provide, a tracking signal usable for determining a distance or velocity of the cornea
Data Source
AI summary
An eye tracking device for integrating in a frame for mounting to a user's head includes a laser output unit for fixing to the frame. The laser output unit is configured to provide a laser beam for illuminating a cornea of the user's eye when in use. The eye tracking device also includes a receiver unit for fixing to the frame. The receiver unit is configured to receive a reflection of the laser beam and to provide a tracking signal usable for determining a distance or velocity of the cornea. The eye tracking device further includes a processing unit for determining a rotation of the user's eye from the tracking signal.