Dual Mode Imaging System Using Multi-Layer Optical Filter
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Solution Overview
Problem
Surveillance cameras face image degradation due to the interference of infrared images with visible light images during the day and reduced signal-to-noise ratio at night, as they are currently unable to effectively switch between visible and infrared light modes without using expensive and complex dual cameras or mechanical switches.
Innovation Solution
A dual mode imaging system with a multi-layered optical filter array that includes two non-overlapping transmission windows, allowing for simultaneous capture of visible and infrared images using a single image sensor, with a color filter array and an infrared filter layer that selectively passes or blocks specific wavelengths, enabling seamless switching between modes based on ambient light conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single camera is used without optical filters, then the device complexity is reduced, but image quality deteriorates due to infrared interference during the day and low signal-to-noise ratio at night
Solution Approach 1:
The optical filter is divided into multiple layers, each layer targeting specific wavelength ranges. The first layer blocks infrared light while transmitting visible light, and the second layer blocks ultraviolet light while transmitting visible light, achieving comprehensive spectral filtering through segmented functional layers
Solution Approach 2:
The optical filter uses composite structure combining multiple filter layers with different spectral characteristics. This composite approach allows simultaneous achievement of infrared blocking, ultraviolet blocking, and visible light transmission, resolving the contradiction between simplicity and image quality
2Manufacturing precision
If an optical filter blocking infrared light is used during daytime, then visible light image quality is improved, but infrared light is blocked preventing nighttime operation
Solution Approach 1:
The optical filter is designed with dynamic spectral characteristics that adapt to different lighting conditions. The filter's multi-layer structure enables it to selectively transmit or block different wavelength ranges based on ambient light conditions, allowing the camera to operate effectively in both daytime and nighttime modes without mechanical switching
Solution Approach 2:
The optical filter serves multiple functions simultaneously: it blocks infrared light during daytime to improve visible image quality, blocks ultraviolet light across all conditions, and allows visible light transmission for both day and night operation. This multi-functionality eliminates the need for mode-specific filters or mechanical switching mechanisms
3Manufacturing precision
If dual cameras with separate optical filters are used, then image quality for both visible and infrared modes is improved, but device complexity and cost increase
Solution Approach 1:
The patent merges the functions of separate visible-light-optimized and infrared-optimized cameras into a single camera system. By integrating a multi-layer optical filter that can selectively transmit or block different wavelength ranges, the system achieves dual-mode capability with a single sensor and lens assembly, significantly reducing device complexity while maintaining image quality
Solution Approach 2:
The single camera system achieves universality by using an optical filter that can adaptively optimize for different spectral conditions. The filter's ability to block infrared and ultraviolet light while transmitting visible light enables the same camera to deliver high-quality images in both daytime and nighttime modes, eliminating the need for dedicated cameras for each mode
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 achieves high-quality visible and infrared images throughout the day and night, reducing image degradation and eliminating the need for dual cameras or mechanical switches, thereby enhancing surveillance camera performance and reducing costs.
Implementation Method 1
An optical filter having a first transmission window including a visible light band and a second transmission window including an infrared light band is provided in front of the image sensor
Implementation Method 2
The optical filter is designed to allow visible light to pass through while blocking infrared light, and vice versa depending on the active transmission window
Implementation Method 3
Each pixel includes a photoelectric conversion element having photoelectric conversion sensitivity in a wavelength range including a visible light region and an infrared light region
Data Source
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AI summary
An imaging system includes an image sensor and an optical filter. The image sensor captures image data in response to incident light. The optical filter filters the light and includes a dual window transmission spectrum. The dual window transmission spectrum includes a first transmission window having a first pass band aligned to pass visible light and a second transmission window having a second pass band overlapping with an absorption band of infrared light in Earth's atmosphere.