Biometric Camera with NIR Light and Bandpass Filter
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Biometric camera systems in mobile devices face challenges such as ambient illumination, motion blur, depth of field issues at close distances, additional cost, and limited field of view, particularly when capturing iris images for reliable identification.
Innovation Solution
A biometric camera system incorporating a near-infrared light source, an extended depth of field (EDOF) imaging lens, a bandpass filter to reject ambient light, and an imaging sensor that converts optical images into electronic signals for processing, with a processor matching iris images against a database for authentication.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If a standard camera is used to capture iris images, then the device structure is simple, but the system cannot operate effectively in high ambient light conditions
Solution Approach 1:
A bandpass filter is introduced as an intermediary component between the lens and sensor to selectively transmit only the wavelength range illuminated by the NIR light source. This mediator blocks ambient visible light while allowing the specific NIR wavelengths to pass through, enabling the camera to operate in high ambient light conditions without requiring a completely redesigned camera system.
Solution Approach 2:
The system changes the operational wavelength parameter from visible light to near-infrared. By illuminating the iris with NIR light and capturing images in the NIR spectrum, the system achieves immunity to visible ambient light interference. This parameter change allows standard camera sensors to be used while achieving the desired ambient light resistance.
2Ease of operation
If the camera is positioned at arm's length to capture the iris, then the user is comfortable, but the field of view is limited and the iris appears small
Solution Approach 1:
The system transitions from capturing wide-field visible light images to capturing magnified narrow-band NIR images. By changing the dimensional characteristics of the captured data (from broad spectral range at arm's length to focused spectral band at close range), the system achieves both user comfort and sufficient iris detail for recognition.
3Adaptability or versatility
If a zoom lens is used to capture the iris at arm's length, then the field of view is sufficient, but the depth of field becomes limited and images become blurry
Solution Approach 1:
The system changes the wavelength parameter to near-infrared, which provides longer depth of field characteristics compared to visible light. This parameter change allows the camera to capture sharp iris images at arm's length distance without requiring zoom lenses, maintaining both adequate field of view and image sharpness.
4Reliability
If additional biometric sensors are added to the mobile device, then the biometric functionality is enhanced, but the device cost and space increase
Solution Approach 1:
The mobile device's existing camera module is made multi-functional by adding a NIR light source and bandpass filter. The same camera sensor that captures visible light for regular photography is also used to capture NIR images for iris recognition. This universal approach allows biometric identification functionality to be added without requiring a separate dedicated biometric sensor, thus avoiding increased device complexity and cost.
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 operates in high ambient light, reduces motion blur, provides clear images at various distances, and is compact, while enabling additional functions like proximity sensing, night-vision, and 3D time-of-flight sensing, ensuring reliable iris identification and user authentication.
Implementation Method 1
a near infrared (NIR) light source on the mobile device that flashes a user of the mobile device with near infrared light during image capture
Implementation Method 2
a bandpass filter located adjacent to the EDOF imaging lens to reject ambient light during image capture
Implementation Method 3
an imaging sensor located adjacent the bandpass filter that converts an optical image of an object into an electronic signal for image processing
Data Source
AI summary
Exemplary embodiments for a biometric camera system for a mobile device, comprise: a near infrared (NIR) light source on the mobile device that flashes a user of the mobile device with near infrared light during image capture; a biometric camera located on the mobile device offset from the NIR light source, the biometric camera comprising: an extended depth of field (EDOF) imaging lens; a bandpass filter located adjacent to the EDOF imaging lens to reject ambient light during image capture; and an imaging sensor located adjacent the bandpass filter that converts an optical image of an object into an electronic signal for image processing; and a processor configured to receive video images of an iris of a user from the image sensor, and attempt to match the video images of the iris with previously registered images stored in an iris database, wherein if a match is found, the user is authenticated.