Optical Fingerprint Scanner with Zero Path Difference Michelson Interferometer
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Solution Overview
Problem
Existing biometric systems primarily scan the outer surface of the finger or palm, which can be susceptible to spoofing and do not effectively detect the liveliness of the internal finger surface.
Innovation Solution
An optical fingerprint scanner with a second prism forming a Zero path difference Michelson interferometer, capable of capturing the internal surface of the finger using coherent gating image detection, thereby providing a more secure and accurate biometric authentication.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional optical fingerprint scanners are used to scan the outer surface of the finger, then the device complexity is low and manufacturing cost is reduced, but the system is susceptible to spoofing and cannot effectively detect the liveliness of the internal finger surface
Solution Approach 1:
The optical system is segmented into two separate optical paths: one for capturing the external fingerprint surface and another for capturing the internal fingerprint surface using coherent gating imaging. This segmentation allows the system to independently process external and internal surface information, enabling spoof detection while maintaining manageable system complexity through modular design
Solution Approach 2:
A second prism is introduced as an intermediary optical element to create a Zero path difference Michelson interferometer configuration. This intermediary component enables the coherent gating imaging function that captures internal surface information without requiring a complete redesign of the entire optical system, thus improving anti-spoof capability while controlling complexity
2Reliability
If multi-spectral or stereo 3D optical imaging is used to enhance security, then the anti-spoof capability is improved, but the data analysis computation and processing complexity increases
Solution Approach 1:
The invention extracts only the essential depth information required for liveness detection by using coherent gating imaging to capture the internal fingerprint surface at a specific depth range (0.5mm to 2.0mm below the skin surface). This extraction approach obtains sufficient anti-spoof information without capturing the full multi-spectral or stereo 3D data, thereby reducing data analysis computation while maintaining liveness detection accuracy
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 enables cheap and less complex optical configuration for anti-spoof biometric finger or palm print scanners, providing enhanced security through internal surface imaging and reduced data analysis requirements compared to multi-spectral and stereo 3D optical imaging.
Implementation Method 1
capable of capturing the internal surface of the finger using coherent gating image detection
Implementation Method 2
Zero path difference Michelson interferometer, capable of capturing the internal surface of the finger using coherent gating image detection
Implementation Method 3
a first optical path (5A) to capture the fingerprint of the external surface, wherein the finger (4) placed on the prism (5) which gets illuminated by light source (6) and the refracted path (5B) from the finger surface ridges
Data Source
AI summary
The present invention relates to an optical fingerprint scanner (3) optics for coherent gating liveness detection involving a second prism to form Zero path difference Michelson interferometer, which forms the image of internal finger surface with the concept of coherent gating image detection. The present invention illustrates the detection of external surface and internal surface of the finger (4) and also provides the clue regarding the liveness detection through coherent gating. The present invention provides a cheap and less complex optical configuration for anti-spoof biometric finger or palm print scanner by using the coherent gating image technique of the Optical Coherence Tomography (OCT). The present invention also provides a lesser data analysis in computation as compared to multi spectral and stereo 3 D optical imaging techniques for anti-spoof finger or palm print analysis.