Monochrome Sensor Color Imaging via Meta-Surface Filter
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Solution Overview
Problem
Current color image sensors have lower resolution and signal-to-noise ratio compared to monochrome sensors due to smaller pixel size, leading to cross-noise and chromatic aberration, and require complex algorithms for color recovery, which increases processor load and can result in color distortion, making them incompatible with mobile devices.
Innovation Solution
A color imaging apparatus using a CMOS sensor with a filter having meta-surfaces that time-sequentially transmit light in specific spectral regions, allowing three monochrome sensors to capture images in synchronization, which are then merged by a processor to form a single color image, utilizing band-pass filters with nanoparticles and refractive index change layers to filter light effectively.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a color image sensor with Bayer filter is used, then color imaging capability is achieved, but resolution and signal-to-noise ratio deteriorate due to smaller pixel size
Solution Approach 1:
The color imaging sensor divides the color information capture into separate channels by using a beam splitter to direct different wavelength ranges (blue, green, red) to separate monochrome sensor arrays. This segmentation allows each sensor array to capture specific spectral information without the pixel size limitations affecting all channels equally, thereby improving overall resolution while maintaining color imaging capability.
Solution Approach 2:
The patent introduces a temporal dimension by sequentially capturing images at different exposure times for each monochrome sensor array. The first monochrome sensor captures an image at a first exposure time, the second at a second exposure time, and the third at a third exposure time. This temporal sequencing allows each sensor to capture spectral information without simultaneous interference, improving resolution and reducing cross-talk between color channels.
2Volume of moving object
If pixel size is decreased to fit mobile devices, then device compactness is improved, but cross-noise and chromatic aberration increase
Solution Approach 1:
The sensor array is segmented into multiple monochrome sensor arrays, each dedicated to capturing specific wavelength ranges. This segmentation isolates the signal paths for different colors, preventing cross-noise between adjacent pixels while maintaining compact pixel sizes suitable for mobile devices. Each monochrome sensor array can be optimized for its specific spectral range without interference from other color channels.
Solution Approach 2:
A beam splitter acts as an intermediary optical element that directs different wavelength ranges to separate monochrome sensor arrays. This intermediary component enables spectral separation before the light reaches the sensor pixels, preventing chromatic aberration and cross-noise by ensuring that only specific wavelength ranges reach each sensor array, even when pixel sizes are reduced for compact device design.
3Adaptability or versatility
If a Bayer filter is used for color separation, then color imaging is enabled, but additional manufacturing operations are required
Solution Approach 1:
The patent extracts the color separation function from a complex Bayer filter system and implements it using simpler monochrome sensor arrays with a beam splitter. By removing the need for complex filter manufacturing operations and replacing them with a beam splitter that directs different wavelengths to separate sensor arrays, the manufacturing process is simplified while maintaining color imaging capability through computational processing.
Solution Approach 2:
The patent replaces the mechanical/optical Bayer filter system with a computational approach. Instead of using physical filters that require complex manufacturing operations, the system uses monochrome sensor arrays that capture spectral information which is then processed computationally to generate color images. This substitution of mechanical filtering with computational processing simplifies manufacturing while maintaining color imaging versatility.
4Volume of moving object
If polymer material filters are used for color separation, then spectral ranges overlap, but this enables compact design
Solution Approach 1:
The spectral separation is segmented into distinct wavelength ranges (blue, green, red) that are directed to separate monochrome sensor arrays by the beam splitter. This segmentation achieves precise spectral separation without relying on polymer filters with overlapping transmission curves, thereby improving manufacturing precision while maintaining compact design through the use of separate sensor arrays for each spectral range.
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
This approach enhances the resolution and signal-to-noise ratio of color imaging, reduces noise and distortion, and allows for a more compact design compatible with mobile devices without the need for complex color interpolation algorithms.
Implementation Method 1
band-pass filters with nanoparticles and refractive index change layers to filter light effectively
Implementation Method 2
refractive index change layers to filter light effectively
Implementation Method 3
a 3-CCD camera has been widely used, and color separation of white light beams in this camera is performed by a 3-CCD dichroic prism that implements a color separation technique is a color television by using three photosensitive matrices or transmission tubes that are separated for each image divided into three colors in red, green and blue spectral ranges. This technique is based on optical color separation by using a dichroic prism that splits light generated due to interference
Data Source
AI summary
A color imaging apparatus includes a filter having a meta surface, and configured to transmit only light in a first spectral region, a second spectral region and a third spectral region in a time sequence, a monochrome sensor on which the filter is disposed, and configured to acquire three different monochrome images in the time sequence by being consecutively exposed three times in synchronization with the filter, and a processor configured to acquire one color image by merging the three different monochrome images.