Compact Iris Imaging System with Dual-Lobed Illumination
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Solution Overview
Problem
Existing iris imaging systems face challenges in capturing high-resolution images of irises at a standoff distance while minimizing light reflection from other facial areas, which degrades image quality and requires a bulky setup.
Innovation Solution
A compact iris imaging system with a dual-lobed irradiance distribution from two illumination sources positioned approximately by an interpupillary distance, focusing light on ocular areas to reduce reflections and enable efficient image capture at a standoff distance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If multiple illumination sources flood the capture volume with uniform light intensity, then adequate illumination of the capture volume and irises is achieved, but light reflection from other parts of the subject's face increases and the system becomes bulky
Solution Approach 1:
The patent applies local quality by transitioning from uniform illumination across the entire capture volume to localized illumination focused specifically on the ocular areas. The illumination sources are positioned and configured to direct light primarily toward the eyes while minimizing illumination of other facial regions, thereby reducing unwanted reflections while maintaining adequate illumination of the irises for imaging
2Object-generated harmful factors
If illumination sources are positioned to focus on ocular areas, then light reflection from other parts of the face is minimized, but the system requires larger separation distance between sources
Solution Approach 1:
The patent resolves the spatial constraint by transitioning from a planar arrangement to a three-dimensional configuration. The illumination sources are positioned at angles relative to the imaging axis, creating a dual-lobed irradiance distribution in three-dimensional space. This angular positioning allows the sources to be closer together while still achieving selective illumination of the ocular areas and minimizing facial reflections
3Device complexity
If standoff distance is increased for compact system arrangement, then system portability is improved, but image quality may degrade due to reduced illumination intensity
Solution Approach 1:
The patent applies dynamics by making the illumination system adaptive to varying standoff distances. The illumination intensity and distribution are dynamically optimized through the dual-lobed configuration, which maintains effective illumination at the required standoff distance of at least 100 mm while allowing for compact system arrangement. The angular positioning of sources ensures that illumination intensity remains sufficient despite the increased distance
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 system effectively captures high-resolution iris images with reduced light reflections, allowing for a compact and portable biometric identification device.
Implementation Method 1
an optical lens having a focal plane with a sensor substantially disposed in the focal plane of the optical lens
Implementation Method 2
Infra-red light is often used for illumination because pigmentation in the iris is more transparent in the infra-red spectrum
Data Source
AI summary
An iris imaging and illumination system is used to resolve and record the fine musculature features of an iris. The system can improve the quality of an iris image and facilitate the image capturing process by focusing illumination on an ocular area of a subject. By limiting illumination of other parts of a face, reflections from the face are reduced. The system has a compact physical arrangement by placing the illumination sources proximate to one another and splaying them in order to focus illumination on the ocular areas of a subject.