Color-Separating Lens Array for Filter-Loss Image Sensors
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Solution Overview
Problem
Existing image sensors utilize color filters that absorb most of the incident light except for one particular color, leading to low light utilization efficiency, typically around 33%, resulting in significant optical loss.
Innovation Solution
Implementing a color separating lens array that separates incident light based on wavelength using a nano-optical structure with transparent high refractive nano-posts, allowing each pixel to focus on different colors and increasing light concentration efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a color filter is used to sense color of incident light, then color detection is achieved, but light utilization efficiency declines to about 33% because most light is absorbed
Solution Approach 1:
The incident light is segmented by wavelength using a color separating lens array that divides the light into different wavelength components. Each wavelength component is directed to a corresponding pixel that is sensitive to that specific wavelength, eliminating the need for absorptive color filters and achieving near 100% light utilization efficiency.
2Loss of energy
If a color separating lens array is used to improve light utilization efficiency, then light concentration efficiency increases, but device complexity increases due to additional nano-optical structures
Solution Approach 1:
Traditional mechanical microlenses are replaced with nano-optical structures consisting of transparent high refractive nano-posts arranged in periodic arrays. These nano-structures achieve the same light focusing function through optical principles (refraction and phase modulation) rather than mechanical curvature, enabling color separation and focusing in a single integrated layer without complex multi-element optical systems.
3Reliability
If traditional microlenses are used for focusing, then focusing function is achieved, but focusing efficiency at high heights is insufficient
Solution Approach 1:
The refractive index parameter of the optical structure is significantly increased by using transparent high refractive materials for the nano-posts. This parameter change enables effective light focusing even at high heights above the sensor surface, where traditional low refractive index microlenses fail to maintain sufficient focusing efficiency. The high refractive index compensates for the increased optical path length and maintains strong light concentration capability.
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
Improves light utilization efficiency and autofocus performance by concentrating light of specific wavelengths on individual pixels, enhancing the overall light transmission and focusing capabilities of image sensors.
Implementation Method 1
a color separating lens array including a first-wavelength light concentration area configured to concentrate, among incident light, the light of the first wavelength on the first pixel, and a second-wavelength light concentration area configured to concentrate, among incident light, the light of the second wavelength on the second pixel
Implementation Method 2
color separating lens array configured to separate incident light based on wavelength
Implementation Method 3
a phase difference between the light of the first wavelength that has traveled through a center of the first pixel-corresponding area and the light of the first wavelength that has traveled through a position spaced apart from the center of the first pixel-corresponding area by 1/2 of a pixel pitch of the sensor substrate is different than a phase difference between the light of the second wavelength that has traveled through a center of the second pixel-corresponding area and the light of the second wavelength that has traveled through a center of the second pixel-corresponding area
Data Source
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AI summary
Provided is an image sensor including a sensor substrate including a first pixel configured to sense light of a first wavelength, and a second pixel configured to sense light of a second wavelength, and a color separating lens array configured to concentrate the light of the first wavelength on the first pixel, and the light of the second wavelength on the second pixel, the color separating lens array including a first pixel-corresponding area corresponding to the first pixel, and a second pixel-corresponding area corresponding to the second pixel, wherein a first phase difference between the light of the first wavelength that has traveled through a center of the first pixel-corresponding area and a center of the second pixel-corresponding area is different than a second phase difference between the light of the second wavelength that has traveled through the center of the first pixel-corresponding area and the center of the second pixel-corresponding area.