Patterned Infrared Cutoff Filters for Dual-Spectral Imaging
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Solution Overview
Problem
Conventional imaging devices face challenges in separating infrared and visible light signals, leading to degraded image quality in the visible spectrum when capturing images in both spectral ranges, and require separate imaging sensors which are costly and bulkier.
Innovation Solution
A dual bandpass filter and patterned infrared cutoff filters are integrated into a single image sensor, allowing visible light to pass while blocking infrared light, enabling simultaneous capture of images in both spectral ranges without compromising image quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If an infrared cutoff filter is placed in front of the image sensor to prevent infrared light from striking the sensor, then visible light image quality is improved, but infrared imaging capability is lost
Solution Approach 1:
The image sensor is divided into two distinct types of pixels: visible light pixels with infrared cutoff filters for high-quality visible imaging, and infrared pixels without such filters for infrared detection. This segmentation allows each pixel type to be optimized for its specific function, resolving the contradiction between visible light quality and infrared capability.
Solution Approach 2:
Different regions of the image sensor have different optical properties. Visible light pixels are equipped with infrared cutoff filters to ensure high-quality visible imaging, while infrared pixels are left without filters to maintain infrared sensitivity. This local differentiation of optical characteristics enables simultaneous optimization for both spectral ranges.
2Adaptability or versatility
If a separate imaging sensor is used for infrared imaging, then infrared imaging capability is improved, but device cost and bulk increase
Solution Approach 1:
The patent merges both visible light and infrared imaging capabilities into a single image sensor by incorporating different pixel types within the same sensor array. This integration eliminates the need for separate sensors, reducing device complexity, cost, and bulk while maintaining dual imaging capability.
Solution Approach 2:
The single image sensor is designed to perform multiple functions: capturing visible light images through visible pixels and capturing infrared images through infrared pixels. This multi-functionality resolves the contradiction by enabling one sensor to replace what would traditionally require two separate sensors.
3Measurement precision
If color pixels in the image sensor receive infrared light, then infrared signal detection is improved, but visible light image quality deteriorates
Solution Approach 1:
The pixel array is segmented into distinct visible light pixels and infrared pixels. Visible light pixels are equipped with infrared cutoff filters to prevent infrared contamination, ensuring high-quality visible imaging. Infrared pixels are specifically designed without such filters to maximize infrared signal detection, thus resolving the contradiction through functional segmentation.
Solution Approach 2:
Different local regions of the sensor have different optical filtering characteristics. Visible light pixels have infrared cutoff filters applied locally to maintain visible image quality, while infrared pixels have no such filters to preserve infrared sensitivity. This local quality differentiation eliminates cross-contamination between spectral ranges.
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 solution allows for high-quality image capture in both visible and infrared spectral ranges using a single image sensor, eliminating the need for separate sensors and reducing device bulk, thereby enhancing imaging capabilities while maintaining image quality.
Implementation Method 1
An infrared cutoff filter is sometimes placed in front of the image sensor to prevent infrared light from striking the image sensor
Implementation Method 2
A layer of infrared light blocking material may be interposed between the array of microlenses and the array of photodiodes. The layer of infrared light blocking material may be patterned to include a plurality of openings
Implementation Method 3
Each pixel may include a photosensor such as a photodiode that receives incident photons (light) and converts the photons into electrical signals
Data Source
AI summary
An image sensor may include a pixel array having visible and infrared imaging pixels for simultaneously detecting light in the visible and infrared spectral ranges. The pixel array may include an array of photodiodes, an array of filter elements formed over the photodiodes, and an array of microlenses formed over the array of filter elements. The filter elements may include infrared cutoff filter elements that block infrared light while passing visible light. The infrared cutoff filter elements may be formed from a patterned layer of infrared blocking material. Each visible imaging pixel includes a portion of the infrared blocking material and a color filter element. Each infrared imaging pixel is aligned with an opening in the infrared blocking material. The opening may be filled with an infrared pass filter element that passes infrared light while blocking visible light.