Vein Imaging Using Pulsed Infrared Radiation
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Solution Overview
Problem
Conventional biometric identification methods using infrared vein imaging face challenges with specular reflection from the skin, particularly on moist or oily surfaces, which reduces the contrast of blood vessel images, making it difficult to achieve reliable facial authentication.
Innovation Solution
The use of short pulses of infrared radiation, with durations less than 10 ns and wavelengths greater than 900 nm, to detect the modulation of pulses by subcutaneous vessels, allowing for higher contrast imaging of blood vessels beneath the skin, utilizing an optical transmitter and receiver with scanning optics to generate images and potentially create 3D maps for enhanced identification.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional infrared illumination is transmitted through the user's hand, then vein patterns can be captured, but specular reflection from moist or oily skin surfaces reduces image contrast and authentication reliability
Solution Approach 1:
The patent applies periodic pulsed illumination instead of continuous infrared illumination. By using short pulses of infrared light, the system captures vein patterns while minimizing the impact of specular reflections from skin surfaces, thereby improving both image contrast and authentication reliability
Solution Approach 2:
The patent changes the temporal parameter of illumination from continuous to pulsed, and adjusts the pulse duration to be short enough to freeze motion and reduce reflection artifacts. This parameter change enables better penetration through skin layers and improved vein pattern visibility
2Measurement precision
If continuous infrared illumination is used to capture vein patterns, then the imaging process is simple, but motion artifacts and specular reflections degrade image quality
Solution Approach 1:
The system uses periodic pulsed illumination with carefully controlled pulse widths to capture high-quality vein images while minimizing motion artifacts and specular reflections. The pulsed nature of the illumination requires synchronized detection but significantly improves image quality
Solution Approach 2:
The system performs preliminary synchronization between the pulsed illumination and the detection process. By pre-coordinating the timing of light pulses with the camera shutter or detector gating, the system captures only the reflected pulsed light, eliminating continuous ambient light interference and improving image quality
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 enables the clear detection of subcutaneous veins with improved contrast and reliability, overcoming the limitations of conventional imaging methods by utilizing short infrared pulses to capture detailed images of blood vessels, enhancing the accuracy of facial authentication.
Implementation Method 1
an optical transmitter, which is configured to emit one or more pulses of infrared radiation toward an area containing a body surface of a living subject
Implementation Method 2
an optical receiver, which is configured to receive the one or more pulses reflected from the body surface
Implementation Method 3
generate an output indicative of a modulation of the pulses by tissue below the body surface
Implementation Method 4
the output of the optical receiver is indicative of a shift in a phase of the received pulses
Implementation Method 5
the processor is further configured to generate, based on a time of flight of the pulses, a three-dimensional map of the body surface
Data Source
AI summary
Imaging apparatus includes an image capture device, which includes an optical transmitter, which is configured to emit one or more pulses of infrared radiation toward an area containing a body surface of a living subject, and an optical receiver, which is configured to receive the pulses reflected from the body surface and to generate an output indicative of a modulation of the pulses by tissue below the body surface. A processor is configured to generate, based on the modulation of the pulses, an image of blood vessels located beneath the body surface within the area.