Metalens Microstructure Pitch Design for Image Sensor Thickness Reduction
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Solution Overview
Problem
Conventional image sensing modules with large curvature lenses suffer from aberration issues, requiring additional compensation lenses that increase the overall thickness of the image sensor, and they have limited optical capabilities making integration challenging.
Innovation Solution
A metalens with a transparent substrate and multiple lenses, where each lens consists of first and second columnar microstructures with different pitches, allowing for focused incidence of light rays of different wavelengths onto specific positions on the photosensitive device substrate, thereby enhancing photoelectric conversion efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a large curvature lens is used to improve the focusing effect of light, then the focusing effect is improved, but the lens is prone to aberration and requires additional compensation lenses
Solution Approach 1:
The lens is divided into multiple columnar microstructures with different pitches arranged in specific patterns. Each columnar structure acts as an independent optical element, collectively achieving the focusing function while reducing aberration. This segmentation allows precise control over light paths for different wavelengths without requiring additional compensation lenses.
Solution Approach 2:
Different regions of the lens have different local structures with varying pitches and orientations. The first columnar microstructures have a first pitch while the second columnar microstructures have a second pitch, creating local optical properties that are optimized for specific wavelength ranges. This local differentiation enables the lens to focus different wavelengths at appropriate positions without introducing aberration.
2Measurement precision
If additional compensation lenses are added to correct image deformation, then aberration is reduced, but the overall thickness of the image sensor increases
Solution Approach 1:
The patent combines the functions of the main lens and compensation lens into a single integrated metalens structure. The multi-pitch columnar microstructures simultaneously achieve focusing and aberration correction that would traditionally require separate lenses, thereby maintaining image quality while reducing the overall thickness of the image sensor.
Solution Approach 2:
The patent introduces a new dimensional approach by using columnar microstructures with varying pitches and orientations in the lateral plane. This two-dimensional structural variation enables optical functions (focusing and aberration correction) that would traditionally require additional lenses in the optical path, thus eliminating the need for increased thickness.
3Device complexity
If conventional lenses and color filter arrays are used, then the system is simpler, but optical capabilities are limited and integration is difficult
Solution Approach 1:
The metalens structure serves multiple functions simultaneously: it acts as a focusing lens, a wavelength-selective element, and an integration bridge between optical components and the photosensitive device. The multi-pitch columnar microstructures can be designed to handle different wavelengths and focus them to specific positions, providing universal optical capability that simplifies the overall system while enhancing versatility.
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 metalens improves the photoelectric conversion efficiency of the image sensor by precisely directing light of different wavelengths to appropriate positions, reducing the need for additional lenses and enhancing integration capabilities, while also reducing the overall thickness of the image sensor.
Implementation Method 1
Each of the lenses includes multiple first columnar microstructures arranged continuously along a first direction and multiple second columnar microstructures arranged continuously along a second direction. A pitch of the first columnar microstructure is different from a pitch of the second columnar microstructure.
Data Source
AI summary
A metalens including a transparent substrate and lenses is provided. The lenses are located on the transparent substrate. Each of the lenses includes first columnar microstructures continuously arranged along a first direction and second columnar microstructures continuously arranged along a second direction. A pitch of the first columnar microstructure is different from a pitch of the second columnar microstructure.