Image Sensor Color Splitter with Dual Refractive Indices
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Solution Overview
Problem
Current image sensors face challenges in efficiently splitting color components of visible light for accurate color acquisition, as existing methods like Bayer filters require interpolation and Fovea sensors are complex with stacked color sensors.
Innovation Solution
An image sensor design incorporating a color splitter structure with two dielectric parts of different refractive indices, generating nanojets that deflect light into distinct directions based on wavelength, allowing for effective separation and recording of blue, green, and red components by pixels.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a Bayer filter is used to discretize color space, then the image sensor can acquire color components, but interpolation is required which reduces measurement precision
Solution Approach 1:
The color splitter structure segments the incident light into different wavelength components (blue, green, red) by directing them to different pixels. This segmentation occurs at the optical level before detection, allowing each pixel to directly measure specific color components without requiring post-processing interpolation, thereby preserving color information accuracy.
Solution Approach 2:
The invention transitions from a two-dimensional color filter array (Bayer filter) to a three-dimensional spatial arrangement where color splitting occurs in the depth dimension. The color splitter structure with height H and lateral dimensions W1, W2 creates a volumetric configuration that separates colors in the propagation direction, enabling direct color component measurement by different pixels without interpolation.
2Measurement precision
If a Fovea sensor with stacked color sensors is used, then three color components per pixel can be recorded, but the device complexity increases
Solution Approach 1:
Instead of stacking multiple sensor layers vertically (Fovea approach), this invention segments the color splitting function into a separate optical structure (color splitter) positioned above a single pixel layer. The color splitter divides incident light into wavelength-specific beams that are directed to different pixels in the same plane, achieving color component separation without requiring multiple stacked sensor layers.
Solution Approach 2:
The color splitter structure acts as an intermediary optical element between the incident light and the pixel array. This mediator performs the color separation function externally, allowing the pixel layer to remain simple while still achieving accurate color component measurement. The intermediary structure handles the complex optical manipulation without increasing pixel layer complexity.
3Measurement precision
If a color splitter structure with single refractive index is used, then the structure is simpler to manufacture, but the color splitting efficiency is reduced
Solution Approach 1:
The color splitter structure employs different refractive indexes in different spatial regions (n2 for the first part, n3 for the second part). This local variation in optical properties enables precise control over light propagation and color splitting angles. Each region's refractive index is optimized for its specific function in the color separation process, improving splitting accuracy while maintaining a relatively simple geometric structure.
Solution Approach 2:
The color splitter is constructed as a composite structure combining materials with different refractive indexes (n1, n2, n3) in specific configurations. This composite approach allows the structure to achieve complex optical functionality (wavelength-dependent beam direction) through material composition rather than complex geometry, potentially simplifying fabrication while maintaining high color splitting precision.
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 proposed solution enables precise color splitting and recording of color components, improving color image acquisition by directing different wavelengths of visible light to specific pixels, enhancing the accuracy and efficiency of color image generation without the need for complex interpolation or stacked sensors.
Implementation Method 1
a color splitter structure with two different refractive indexes... each of said dielectric part having a first refractive index n1, said first part having a second refractive index n2, and said second part having a third refractive index n3
Data Source
AI summary
The disclosure relates to an image sensor comprising pixels for acquiring color information from incoming visible light, wherein said image sensor comprising at least two pixels being partially covered by a color splitter structure comprising a first part and a second part, each of said first and second parts being adjacent to a dielectric part, each of said dielectric part having a first refractive index n1 (said first part having a second refractive index n2, and said second part having a third refractive index n3, wherein n1<n3<n2, and wherein according to a cross section, the first part of said color splitter structure has a first width W1, a height H and the second part of said color splitter structure has a second width W2, and the same height H, and wherein said color splitter structure has a first, a second and a third edges at the interfaces between parts having different refractive indexes, each edge generating beams or nanojets, and wherein said height H is close to a value Formul (I), where ΘB1 and ΘB3 are tan ΘB1 and are respectively radiation angles of a first and a third beams generated by said first and third edges, and wherein one of said at least two pixels records light associated with a first wavelength λ-1 and the other of said at least two pixels records light having a spectrum in which no or few electromagnetic waves having a wavelength equal to λ-1 are present, wherein said first wavelength λ-1 being either high or small in a range of visible light.