Subcutaneous Bloodstream Authentication via Laser Speckle Imaging
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Solution Overview
Problem
Existing personal authentication methods using fingerprint patterns based on laser speckles are vulnerable to counterfeiting by silicone replicas and are affected by low temperatures, which reduce bloodstream detection accuracy.
Innovation Solution
Measuring subcutaneous bloodstream by irradiating a laser beam to the finger pad and focusing reflected light onto an image sensor plane using an optical system, with the laser beam and observation region arranged separately to detect internal bloodstream variations synchronized with heartbeats, and comparing the resulting bloodstream map with pre-registered data for authentication.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a fingerprint pattern is used for authentication, then authentication accuracy is improved, but the system becomes vulnerable to counterfeiting by silicone replicas
Solution Approach 1:
The patent extracts the bloodstream pattern from the subcutaneous tissue and uses it as the authentication feature instead of the fingerprint pattern. The laser beam penetrates the skin to visualize the blood vessels beneath, which are unique to each individual and cannot be replicated by silicone counterfeits. This extraction of the underlying bloodstream pattern resolves the vulnerability to surface-level counterfeiting while maintaining authentication accuracy.
Solution Approach 2:
The patent transitions from two-dimensional fingerprint pattern recognition to three-dimensional bloodstream pattern visualization by using laser penetration through the skin. This dimensional change allows detection of the subsurface vascular structure, adding a new layer of authentication that is inaccessible to surface replicas and significantly enhances anti-counterfeiting capability.
2Adaptability or versatility
If laser speckles are used to detect bloodstream, then authentication capability is improved, but detection accuracy decreases in low temperature conditions
Solution Approach 1:
The patent applies preliminary heating to the finger pad before authentication to ensure adequate bloodstream flow and laser speckle detection. By pre-warming the tissue, the system compensates for cold-induced vasoconstriction and maintains detection accuracy across varying environmental temperatures, ensuring consistent authentication capability.
3Ease of manufacture
If a thin silicone film with fingerprint pattern is affixed to the finger, then counterfeiting becomes possible, but the sensor still perceives the underlying bloodstream wrongly as alive
Solution Approach 1:
The patent introduces a threshold discrimination mechanism as an intermediary between the laser speckle detection and the living finger determination. By comparing the detected speckle pattern intensity against a predetermined threshold, the system can distinguish between the dynamic speckles from living blood flow and the static or anomalously weak patterns from counterfeits, even when a thin silicone film is present.
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 enhances authentication accuracy by distinguishing real fingers from counterfeits and maintains detection even in cold conditions by focusing on internal bloodstream signals, making it difficult to counterfeit the model based on the combination of two-dimensional patterns and time-axis variations.
Implementation Method 1
When a laser beam is irradiated to a living body, an intensity distribution of reflected and scattering light forms dynamic laser speckles (random speckled pattern) due to moving scattering particles such as blood cells.
Implementation Method 2
an intensity distribution of reflected and scattering light forms dynamic laser speckles
Implementation Method 3
focusing light reflected from a subcutaneous blood vessel layer onto an image sensor plane as laser speckles by using an optical system
Data Source
AI summary
In a personal authentication method using the subcutaneous bloodstream measurement where an expanded laser beam is irradiated onto a finger pad, light reflected from a subcutaneous blood vessel layer is imaged on an image sensor as a laser speckle using an optical system, a quantity that represents the rate of change with respect to time of the amount of light received for each pixel of the laser speckle is calculated, the values are used as a two-dimensional map to obtain a map showing the bloodstream of the finger pad, and the bloodstream map is comparison-checked against pre-registered data of individuals, the laser speckle is imaged on the image sensor using a region separate from a region irradiated by the laser beam as an observation region of the image sensor. A device for use in the method is also provided. Relating to a method and device for authentication using, e.g., a finger print pattern on the basis of the laser speckle, an improved technique capable of extracting, e.g., the finger print pattern accurately is provided.