Eye Tracking via Laser Doppler Interferometry
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Solution Overview
Problem
There is a need for an accurate, lightweight, and compact eye-tracking system for head-mounted display devices that does not require additional optical components like external cameras, reducing size and cost, and eliminating the need for complex computation steps like background filtering.
Innovation Solution
The system uses a Doppler-interferometer method with a first optical device that includes a light source with an optical cavity, emitting coherent light towards the eye and detecting the modulated intensity of the feedback light to determine eye movement information without image processing, thereby providing accurate eye-tracking without the need for external cameras or complex computations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If imaging-based eye-tracking systems with external cameras are used, then eye-tracking functionality is provided, but device size and cost increase
Solution Approach 1:
The patent combines the light source and light sensor into a single integrated optical device, eliminating the need for separate external cameras and additional optical components. This integration achieves compact eye-tracking functionality while maintaining measurement accuracy through the self-mixing interferometry technique that uses the light source's own cavity as the sensing element.
Solution Approach 2:
The light source serves dual functions: generating coherent light for illumination and acting as the sensing element through its optical cavity. The cavity's resonance characteristics provide the measurement signal, eliminating the need for separate sensing components and reducing overall device complexity while maintaining eye-tracking precision.
2Measurement precision
If imaging-based eye-tracking systems with external cameras are used, then eye-tracking functionality is provided, but manufacturing cost increases
Solution Approach 1:
The patent integrates the light source and light sensor into a single optical device, reducing the bill of materials and assembly complexity. This consolidation eliminates the need for separate external cameras and additional optical components, thereby reducing manufacturing cost while preserving eye-tracking accuracy through the self-mixing interferometry method.
Solution Approach 2:
The light source's optical cavity serves as both the light generation medium and the sensing element. This self-service approach eliminates the need for separate expensive sensing components and complex optical assemblies, reducing manufacturing cost while maintaining measurement precision through the cavity's inherent resonance properties.
3Measurement precision
If imaging-based eye-tracking systems are used, then eye-tracking functionality is provided, but power consumption increases due to complex computation
Solution Approach 1:
The patent replaces complex image processing and computational algorithms with a direct optical measurement approach. The self-mixing interferometry technique converts eye movements into direct intensity modulation signals from the light source cavity, eliminating the need for computationally intensive image analysis and background filtering, thereby reducing power consumption while maintaining tracking accuracy.
Solution Approach 2:
The optical cavity provides direct intensity modulation in response to eye movements, generating measurement signals that require minimal processing. This self-service mechanism eliminates the need for complex computation steps like background filtering and image recognition, significantly reducing power consumption while preserving eye-tracking precision.
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 results in a lightweight and compact eye-tracking system that provides accurate eye-tracking information, reducing size, cost, and power consumption, while eliminating the need for additional optical components and complex computation steps.
Implementation Method 1
The first light source is positioned to output first coherent light toward an eye of a user and to receive at least a first portion of the first coherent light back from the eye of the user as feedback light. The feedback light enters the first optical cavity and causes modulation of an intensity of the first coherent light.
Implementation Method 2
The systems and methods disclosed in this description use a Doppler-interferometer method to track the movement of the eye
Data Source
AI summary
An eye-tracking device includes an optical device that includes a light source with an optical cavity and a light sensor. The light source is positioned to output coherent light toward an eye of a user and receive at least a portion of the coherent light back from the eye of the user as feedback light. The feedback light enters the optical cavity and causes modulation of an intensity of the coherent light. The light sensor is optically coupled with the light source for detecting the modulated intensity of the coherent light and generating one or more signals based on the detected intensity of the coherent light. The eye-tracking device also includes one or more processors that are coupled to the optical device for determining, from the one or more signals, movement information of the eye. A method of detecting movement of an eye using the eye-tracking device is also disclosed.