Multi-Lens Iris Sensor Cluster for Wide Focus Range
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Solution Overview
Problem
Conventional image acquisition systems for iris biometric recognition face challenges in achieving sharp focus across a range of distances suitable for smartphones, particularly due to cost and space constraints, leading to suboptimal image quality and increased complexity in capturing both iris and face regions simultaneously.
Innovation Solution
A multi-optic single-sensor image acquisition system comprising a cluster of fixed-focus lenses with different angular fields of view and focal lengths, each designed to maintain image quality and resolution across a wide range of distances, utilizing wafer scale technology to minimize size and maximize depth of field, allowing for comfortable user positioning and flexible iris image acquisition.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a fixed focus lens is used with a focus peak at 20 cm, then image quality at that specific distance is optimized, but the usable focus range is limited to only 15-25 cm
Solution Approach 1:
The patent divides the imaging system into multiple fixed-focus lenses, each optimized for a specific distance range. Instead of using one lens that tries to cover all distances, the system segments the focus ranges and assigns dedicated lenses to each segment, achieving both sharp focus and broad coverage.
Solution Approach 2:
The patent creates a multi-functional optical system where multiple lenses work together to provide universal distance coverage. Each lens serves a specific function for its optimized range, but collectively they provide universal adaptability across the entire desired focus spectrum from 15 cm to beyond 45 cm.
2Adaptability or versatility
If a variable focus lens is used, then the focus range is extended, but the size of iris regions changes and auto-focus mechanisms increase complexity
Solution Approach 1:
The patent segments the variable focus requirement into multiple fixed-focus components. Each lens is statically optimized for a specific range, eliminating the need for complex auto-focus mechanisms while maintaining adaptability across all distances through the lens cluster approach.
Solution Approach 2:
Instead of using a single variable focus lens that changes parameters dynamically, the patent inverts the approach by using multiple fixed-focus lenses with different parameters. The system achieves variability through selection among fixed options rather than through dynamic adjustment, simplifying the overall device complexity.
3Adaptability or versatility
If the field of view is increased to capture both eyes at 15 cm distance, then the horizontal field of view angle reaches approximately 37 degrees, but image resolution and iris pattern quality may be compromised
Solution Approach 1:
The patent segments the field of view requirement by assigning different lenses to capture different portions of the scene at different distances. This allows each lens to optimize for its specific angular range while collectively covering the entire 37-degree horizontal field of view with sufficient resolution for iris recognition.
Solution Approach 2:
The patent applies local quality by optimizing each lens in the cluster for its specific region of the scene. Each lens is designed with appropriate focal length and aperture to deliver high-resolution iris images for its designated angular sector, ensuring that every part of the wide field of view maintains adequate 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
The system enables high-quality iris image capture across a range of 200-300 mm, maintaining resolution and depth of field, thereby enhancing flexibility and usability in biometric applications while being compact enough for smartphone integration.
Implementation Method 1
a multi-optic single-sensor image acquisition system including a cluster of fixed-focus lenses mounted to the image sensor with parallel spaced apart optical axes
Data Source
AI summary
An image acquisition system for acquiring iris images for use in biometric recognition of a subject includes an optical system comprising a cluster of at least 2 lenses arranged in front of a common image sensor with each lens optical axis in parallel spaced apart relationship. Each lens has a fixed focus and a different aperture to provide a respective angular field of view. The lens with the closest focus has the smallest aperture and the lens with the farthest focus has the largest aperture so that iris images can be acquired across a focal range of at least from 200 mm to 300 mm.