Nanopost Color-Separating Lens Array for Low-Loss Image Sensors
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Solution Overview
Problem
Image sensors face low light utilization efficiency due to the absorption of unwanted light colors by color filters, leading to significant light loss and performance variations with chief ray angles.
Innovation Solution
An image sensor design incorporating a color separation lens array with nanoposts arranged in layers to separate incident light by wavelengths, condensing light on specific pixels without a color filter, and an anti-reflection layer to improve light transmission.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a color filter is used to sense light color, then light color separation is achieved, but light utilization efficiency deteriorates due to absorption of unwanted colors
Solution Approach 1:
The patent removes the color filter from the optical path and extracts only the necessary light separation function, implementing it instead through wavelength-selective nanoposts that guide different wavelengths to different pixels without absorbing light
Solution Approach 2:
The patent replaces the optical filtering mechanism (color filter) with a waveguide-based directional coupling mechanism using nanoposts, where light separation is achieved through controlled coupling between waveguide modes rather than absorption and re-emission
2Loss of energy
If a color separation lens array is used to separate light by wavelengths, then light utilization efficiency is improved, but performance variation with chief ray angle worsens
Solution Approach 1:
The patent applies different nanopost configurations (different heights, positions, and arrangements) to different regions of the sensor array, optimizing each local region's light separation performance for its specific chief ray angle range while maintaining overall system consistency
Solution Approach 2:
The patent makes the nanopost characteristics dynamic relative to the incident light angle, where the effective coupling strength and wavelength separation characteristics adapt automatically based on the chief ray angle of incoming light
3Reliability
If nanoposts are arranged in multiple layers to reduce performance variation, then manufacturing complexity increases
Solution Approach 1:
The patent divides the nanopost array into multiple layers with different functions: first-layer nanoposts for primary wavelength separation and second-layer nanoposts for fine-tuning and compensation, where each layer can be optimized independently
Solution Approach 2:
The patent implements a hierarchical nanopost structure where second-layer nanoposts are positioned within the projection of first-layer nanoposts, creating a nested configuration that maximizes space utilization and light interaction
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
Enhances light utilization efficiency and reduces performance variations across different chief ray angles, leading to improved image quality and consistent channel differences between pixels.
Implementation Method 1
a color separating lens array spaced apart from the sensor substrate in a vertical direction that is perpendicular to the two horizontal direction, and configured to separate incident light according to wavelengths, and condense the incident light on each of the first to fourth pixels
Implementation Method 2
an anti-reflection layer to improve light transmission
Data Source
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Figure 2B
AI summary
An image sensor may include pixel groups arranged in a Bayer pattern and a color separating lens array that separates incident light by wavelengths and concentrates the separated incident light on the pixels. The color separating lens array may include pixel corresponding groups, with each group having regions containing nanoposts in two layers. In each of the pixel corresponding groups in each of the two layers, there are a central group and a plurality of peripheral groups. The displacements of arrangement centers of the nanoposts in at least two of the peripheral groups have variations.