Metasurface Image Sensor Light Splitting for Color Fidelity
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Solution Overview
Problem
The existing Bayer color filter system in image sensors has a low light utilization efficiency, as it filters out more than 70% of light, resulting in color distortion and reduced imaging quality.
Innovation Solution
The implementation of an image sensor with an array of metasurface structures and optical-to-electrical conversion units, where the metasurface structures are designed to transmit optical signals at each frequency band to the corresponding conversion elements, replacing the traditional light filtering manner with a light splitting approach.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a Bayer color filter system is used to obtain color information, then color picture quality is improved, but light utilization efficiency deteriorates (more than 70% of light is filtered out)
Solution Approach 1:
The patent segments the optical signal by frequency band using metasurface structures with different rotation angles. Each metasurface structure directs a specific frequency band to a corresponding optical-to-electrical conversion element, replacing the traditional Bayer filter's wavelength-selective absorption with a spatial segmentation approach that preserves more light energy.
Solution Approach 2:
The patent replaces the chemical/optical filtering mechanism of Bayer color filters with a geometric optical mechanism using metasurface structures. The metasurfaces use subwavelength microstructures with specific rotation angles to redirect different frequency bands, substituting the absorption-based filtering with a reflection/refraction-based directional routing system that maintains higher light transmission efficiency.
2Loss of information
If traditional light filtering is used to separate frequency bands, then color information is obtained, but optical signal loss increases
Solution Approach 1:
The patent introduces metasurface structures as intermediary elements between the incoming optical signal and the optical-to-electrical conversion elements. These metasurfaces act as frequency-dependent mediators that redirect different frequency bands to appropriate conversion elements without absorbing the light, thereby preserving optical signal intensity while achieving frequency band separation.
Solution Approach 2:
The patent changes the routing parameter (direction of light propagation) based on the frequency band parameter. By adjusting the rotation angle of the metasurface structure according to the desired frequency band, the system dynamically routes different frequencies to different conversion elements, maintaining signal intensity while achieving spectral separation.
3Adaptability or versatility
If a rotationally symmetric structure with rotation angle less than or equal to 90 degrees is used, then polarization dependence is reduced, but structural complexity increases
Solution Approach 1:
The patent employs rotationally asymmetric metasurface structures with specific rotation angles (less than or equal to 90 degrees) to achieve polarization-independent operation. The asymmetric geometry of the meta-atoms creates equivalent optical responses for different polarization states, eliminating polarization dependence while maintaining a relatively simple fabrication process compared to more complex symmetric designs.
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 solution improves light transmittance across spectral channels, enhances overall light utilization of the image sensor, and increases the imaging quality by reducing color information loss and improving color fidelity.
Implementation Method 1
An existing light filtering manner is replaced with a light splitting manner, to avoid an optical signal loss in an optical filtering process
Implementation Method 2
The microstructure and the first substrate are configured to transmit an optical signal at each frequency band to an optical-to-electrical conversion element corresponding to each frequency band
Implementation Method 3
The image sensor is configured to convert an optical signal of an image into an analog electrical signal
Data Source
AI summary
An image sensor includes an array of metasurface structures and an array of optical-to-electrical conversion units. The array of metasurface structures is located above the array of optical-to-electrical conversion units. A first optical-to-electrical conversion unit in the array of optical-to-electrical conversion units includes a plurality of optical-to-electrical conversion elements, each optical-to-electrical conversion element in the first optical-to-electrical conversion unit corresponds to one frequency band in a spectrum. A first metasurface structure in the array of metasurface structures includes a first substrate and a microstructure located above the first substrate. The first substrate and the microstructure are configured to transmit an optical signal at each frequency band to an optical-to-electrical conversion element corresponding to each frequency band. The microstructure is a rotationally symmetric structure, and a rotation angle of the rotationally symmetric structure is less than or equal to 90 degrees.