Variable-Height Microlens Image Sensor for Chromatic Aberration
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Solution Overview
Problem
Chromatic aberration occurs in image sensors due to differences in refractive indices for different wavelengths of light, leading to focal length discrepancies and image distortion.
Innovation Solution
An image sensor design with a color filter layer, microlens layer, and photosensitive element layer, where the microlenses have varying heights to match focal lengths based on chromatic aberration data, ensuring accurate focusing for different color channels.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional lens structure is used, then the lens structure is simple, but chromatic aberration occurs due to different refractive indices for different wavelengths
Solution Approach 1:
The patent introduces a new dimension (vertical height) to the microlens layer to correct chromatic aberration. By varying the heights of microlenses corresponding to different color channels (R, G, B), the optical path lengths are adjusted to compensate for different refractive indices, thereby correcting focal length discrepancies without adding complex lens elements.
Solution Approach 2:
The patent applies local quality by making each microlens have a specific height tailored to its corresponding color channel. The microlenses are not uniform but have localized variations in height (hR, hG, hB) optimized for their respective wavelengths, allowing precise correction of chromatic aberration at each pixel location.
2Manufacturing precision
If microlenses have uniform heights, then the manufacturing process is simple, but focal lengths cannot be matched for different color channels
Solution Approach 1:
The patent changes the height parameter of microlenses based on chromatic aberration characteristics of different color channels. By adjusting the height parameter (hR, hG, hB) for each microlens type, the optical path lengths are modified to achieve matched focal lengths for R, G, and B channels, directly addressing the chromatic aberration issue.
3Reliability
If chromatic aberration is not corrected, then the lens structure remains simple, but image distortion and color fringing occur
Solution Approach 1:
The patent utilizes the vertical dimension (height variation) of the microlens layer to correct chromatic aberration. This approach embeds the correction function within the existing image sensor structure rather than adding external optical elements, maintaining compactness while improving image quality.
4Manufacturing precision
If conventional focusing is used, then all color channels share the same focal point, but focal length discrepancies occur due to refractive index differences
Solution Approach 1:
The patent implements local quality optimization by assigning specific heights to microlenses for each color channel. This allows each color channel to have its optical path precisely tuned to achieve a common focal point, thereby matching focal lengths and maximizing photosensitive efficiency for all channels simultaneously.
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 design corrects chromatic aberration, allowing for improved image quality and simplified lens structures by optimizing focal lengths for each color channel, enhancing photosensitive efficiency and reducing lens complexity.
Implementation Method 1
The light may have different refractive indices depending on the wavelength. The incident light may be refracted when passing through the lens
Implementation Method 2
the image sensor may convert an amount of light incident per pixel from the light incident through the lens into charges
Data Source
AI summary
An image sensor is provided. The image sensor includes a color filter layer including a plurality of color filters including at least one color channel, the plurality of color filters being disposed on one plane of the image sensor, a microlens layer disposed on the upper end of the color filters and including a plurality of microlenses, and a photosensitive element layer including a plurality of photosensitive elements corresponding to the plurality of color filters, wherein the plurality of microlenses are configured to have different heights so as to match the focal lengths of the color channels of light corresponding to the color filters based on chromatic aberration data according to the color channels of light.