Two-Factor Authentication Optical Film for Biometric Spoofing
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Solution Overview
Problem
Current security measures in mobile devices face challenges in preventing spoofing and ensuring liveness detection, particularly in biometric authentication systems, where methods like fingerprint recognition can be fooled by fake or disembodied digits, necessitating a solution that differentiates between real and fake biometric inputs without altering display colors.
Innovation Solution
An optical film with a multi-layer structure, featuring a layer thickness gradient and specific transmission properties in near-infrared and visible wavelength ranges, allowing for high transmission in infrared for biometric measurements while maintaining minimal visible impact, enabling effective two-factor authentication without significantly altering display colors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a multi-layer optical film is used to enable biometric authentication in near-infrared range, then authentication security is improved, but the device complexity increases
Solution Approach 1:
The optical film is divided into multiple polymeric layers (at least 200 layers) with varying thicknesses, where each layer contributes to the overall optical filtering function. This segmentation allows precise control of near-infrared transmission while blocking visible light, enabling secure biometric authentication without compromising display visibility.
Solution Approach 2:
Different regions of the optical film have different layer thicknesses tailored for specific wavelength ranges. The film exhibits high transmission (Tp>30%) in the near-infrared range (first wavelength range) for biometric sensing, while blocking visible light (third wavelength range) to prevent spoofing. This local quality differentiation resolves the contradiction by providing wavelength-specific optical properties.
2Reliability
If the optical film blocks visible light to prevent spoofing, then authentication reliability is improved, but display color integrity deteriorates
Solution Approach 1:
The optical film's transmission properties are dynamically optimized for different wavelength ranges rather than applying a uniform filtering approach. The film allows high near-infrared transmission for authentication while selectively blocking only specific visible wavelength ranges, maintaining display color integrity through wavelength-specific transmission characteristics.
Solution Approach 2:
The film's optical parameters (transmission percentage, layer thickness) are changed across different wavelength ranges. In the near-infrared range, transmission is high (Tp>30%), while in the visible range, transmission is controlled (TA3<Tp/30). This parameter differentiation enables simultaneous achievement of anti-spoofing capability and display color integrity.
3Measurement precision
If the optical film allows high near-infrared transmission for biometric sensing, then sensing accuracy is improved, but visible light transmission increases causing display color alteration
Solution Approach 1:
The optical spectrum is segmented into distinct wavelength ranges with different transmission characteristics. The film structure (200+ layers with varying thicknesses) is designed to provide high transmission in the near-infrared range (first wavelength range) for accurate biometric sensing, while implementing selective blocking in visible wavelength ranges to prevent display color alteration.
Solution Approach 2:
The optical film exhibits local quality differences across the electromagnetic spectrum, with high transmission properties optimized for near-infrared wavelengths (where biometric sensing occurs) and selective absorption properties for visible wavelengths. This local optimization resolves the contradiction by providing wavelength-specific transmission control.
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 optical film enables robust two-factor authentication by differentiating between real and fake biometric inputs with high accuracy, ensuring secure device access while maintaining the visual integrity of the display.
Implementation Method 1
An optical film with a multi-layer structure, featuring a layer thickness gradient and specific transmission properties in near-infrared and visible wavelength ranges
Implementation Method 2
Each of the polymeric layers has an average thickness of less than about 150 nm. A thinnest polymeric layer in the plurality of polymeric layers is disposed closer to the first outer layer
Data Source
AI summary
An optical film (100) includes a plurality of polymeric layers (40) disposed between opposing first (11) and second (12) outer layers, a thinnest polymeric layer in the plurality of polymeric layers disposed closer to the first outer layer (11) and a thickest polymeric layer disposed closer to the second outer layer (12). A layer thickness gradient of the optical film (100) includes first (43) and second (45) portions joined by a step portion (20), a change in thickness across the step portion (20) at least 5 times greater than a change in thickness across each of the first (43) and second (45) portions, wherein the optical film (100) has a first average transmission percentage, TA1, in a first wavelength range, a peak transmission percentage, Tp, in a different, second wavelength range. The first wavelength range and the second wavelength range are separated by a third wavelength range with a third average transmission percentage, TA3, such that TA1>Tp>30(TA3).