FMCW Eye Authentication Using 3D Structural Lidar Signals
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Solution Overview
Problem
Existing authentication methods for head-mounted devices using cameras struggle to reliably identify users based on eye features, particularly in varying lighting conditions and user interactions such as blinking, leading to inefficiencies and resource wastage.
Innovation Solution
Employing a frequency modulated continuous wave (FMCW) lidar sensor to analyze the eye's structural and biological properties by converting reflected signals to the frequency domain, using Fourier transforms to identify unique anatomical features and biological indicators, and generating three-dimensional volumetric data to determine user identity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a camera is used to obtain eye information for authentication, then the device can perform authentication, but the authentication reliability deteriorates in varying lighting conditions and when users blink
Solution Approach 1:
The patent replaces the camera-based optical authentication system with an FMCW lidar-based system. The lidar sensor emits frequency-modulated continuous wave signals that penetrate the eye and reflect off internal structures, enabling authentication based on structural information rather than surface images. This substitution eliminates dependency on visible light conditions and eye opening state, as the lidar signals can penetrate the closed eyelid and capture eye structure data regardless of external lighting or blinking.
Solution Approach 2:
The patent changes the authentication parameter from surface optical properties (captured by camera) to internal structural properties (captured by FMCW lidar). By measuring the frequency shifts of reflected lidar signals, the system extracts structural information about eye components such as the cornea, iris, and retina. This parameter change allows authentication to proceed reliably even when the eye is closed or lighting conditions vary, as these factors do not affect the structural measurements.
2Productivity
If camera-based authentication is used, then user identification can be performed, but resource wastage occurs due to false negatives and repeated authentication attempts
Solution Approach 1:
The patent replaces the camera-based authentication system with an FMCW lidar-based system that captures structural information about the eye. This substitution enables more reliable authentication by measuring invariant structural properties rather than surface appearance, which reduces false negatives and the need for repeated authentication attempts, thereby improving efficiency and reducing resource wastage.
Solution Approach 2:
The FMCW lidar system performs multiple functions simultaneously: it captures structural information for authentication, detects eye presence, and determines eye state (open/closed) all through the same signal measurements. This self-service capability eliminates the need for separate sensors and processing systems, reducing overall resource consumption while improving authentication reliability.
3Reliability
If FMCW lidar sensor is used to obtain structural information about the eye, then authentication reliability is improved, but device complexity increases
Solution Approach 1:
The FMCW lidar sensor serves multiple functions: it emits frequency-modulated continuous wave signals, measures frequency shifts of reflected signals, captures structural information about eye components, and enables authentication. By consolidating these functions into a single sensor system, the patent reduces overall device complexity compared to using separate cameras, illuminators, and processing systems, while achieving superior authentication reliability.
4Measurement precision
If Fourier transform is used to convert reflected signals to frequency domain, then material properties of eye can be identified, but processing complexity increases
Solution Approach 1:
The patent uses Fourier transform to convert the time-domain reflected lidar signals into the frequency domain, where distinct frequency components correspond to different eye structures (cornea, iris, retina). This mathematical transformation enables precise identification of material properties and structural characteristics by analyzing frequency shifts and signal intensities at different frequencies, achieving high measurement precision through computational methods rather than complex hardware.
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
Enhances user authentication by accurately identifying users through unique eye features, ensuring reliable authentication even in varying conditions, reducing false negatives, and optimizing resource usage.
Implementation Method 1
An authentication system may use a frequency modulated continuous wave lidar sensor (FMCW sensor) to obtain structural information about an eye
Implementation Method 2
The FMCW sensor may send a signal with a shaped frequency towards the eye and determine, based on the shaped frequency of a received signal
Implementation Method 3
The authentication system may convert the signal to the frequency domain by using a Fourier transform. The reflected signal, in the frequency domain, may include peaks at particular frequencies which may correspond to anatomical features of the eye
Implementation Method 4
The authentication system may detect movement of the eye based on the frequency of the peaks using the Doppler effect
Data Source
AI summary
An authentication system may use a frequency modulated continuous wave sensor to send and receive a signal towards an eye of a user. The received signal may include information about the structure and material properties of the eye. The authentication system may use the information that is included in the received signal to determine whether the sent signal is directed to an eye, whether the eye is open or closed, and whether the user corresponding to the eye is a particular previous user.