Segmented Optical Filter for Iris Recognition
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Consumer devices, such as smartphones, face challenges in implementing iris recognition due to the small size and curved surface of the iris, occlusions, specular reflections, and the need for specialized NIR illumination, which increases costs and complexity, especially when trying to optimize for both visible and NIR image capture.
Innovation Solution
A smartphone optical system that focuses both visible and near-infrared spectral regions onto a multi-wavelength sensor using a simple lens assembly with a filter allowing NIR radiation to pass through a larger aperture and a central aperture for visible light, enabling simultaneous imaging with a smaller field of view for NIR, thus reducing costs and complexity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a dedicated imaging system with specialized NIR illumination is used for iris recognition, then the quality of NIR images is improved, but the cost and device complexity increase
Solution Approach 1:
The optical system uses a single lens assembly that can focus both visible and NIR light onto the same sensor, allowing the device to perform both visible imaging and NIR iris recognition without requiring separate dedicated imaging systems. This multi-functionality reduces device complexity while maintaining NIR image quality.
Solution Approach 2:
The lens assembly is segmented into different regions with different optical properties: a central region for visible light and a peripheral region for NIR light. This segmentation allows each region to be optimized for its specific wavelength while using a single integrated optical component, reducing overall system complexity.
2Adaptability or versatility
If a movable NIR filter is added to an imaging system optimized for both visible and NIR image capture, then NIR imaging capability is improved, but the cost increases
Solution Approach 1:
Instead of using a movable filter, the optical system uses a static lens assembly with segmented regions - a central region for visible light and a peripheral region for NIR light. This eliminates the need for movable components while maintaining the ability to capture both visible and NIR images, reducing manufacturing cost.
Solution Approach 2:
The system merges the visible and NIR optical paths into a single lens assembly that focuses both wavelengths onto the same sensor. This integration eliminates the need for separate optical systems or movable filters, reducing cost while maintaining versatility.
3Device complexity
If the same lens assembly is used for both visible and NIR light, then device complexity is reduced, but the spatial resolution for NIR images may be insufficient
Solution Approach 1:
The lens assembly is segmented into a central region for visible light and a peripheral region for NIR light, where each region is optimized for its specific wavelength. This segmentation allows the system to maintain high spatial resolution for NIR images while using a single integrated optical component, thus reducing overall system complexity.
Solution Approach 2:
Different regions of the lens assembly have different optical properties tailored to their specific functions: the central region is optimized for visible light while the peripheral region is optimized for NIR light. This local optimization ensures high spatial resolution for NIR images without requiring a completely separate optical system.
4Adaptability or versatility
If a dual band singlet with aperture cut-out is used, then both visible and NIR imaging is enabled, but the manufacturing complexity increases
Solution Approach 1:
Instead of using a complex dual band singlet with aperture cut-outs, the system uses a simpler lens assembly with segmented regions - a central region for visible light and a peripheral region for NIR light. This segmentation approach achieves dual band imaging while reducing manufacturing complexity by avoiding the need for precise aperture cut-outs and complex lens geometries.
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
Enables biometric identification by acquiring NIR images with sufficient spatial resolution for iris recognition on a single sensor, similar to visible light images, while maintaining optical quality and cost-effectiveness, suitable for consumer devices.
Implementation Method 1
a filter allowing NIR radiation to pass through a larger aperture and a central aperture for visible light
Implementation Method 2
A smartphone optical system that focuses both visible and near-infrared spectral regions onto a multi-wavelength sensor
Data Source
AI summary
An optical system for an image acquisition device comprises a filter comprising a central aperture arranged to transmit both visible and selected near infra-red (NIR) wavelengths and a peripheral aperture arranged to block visible wavelengths and to transmit the NIR wavelengths. An image sensor comprises an array of pixels including pixels sensitive to visible wavelengths and corresponding pixels sensitive to the NIR wavelengths. A lens assembly is axially located between the filter and the image sensor and comprises a plurality of lens elements. The lens elements are arranged to simultaneously focus NIR light received from a given object through central and peripheral apertures of the filter and visible light received from the object through the central aperture onto the sensor surface.