Single-Plate Image Sensor with Variable Pixel Density for Axial Chromatic Aberration Control
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Solution Overview
Problem
Multiband cameras with single-plate image sensors and five or more color bands face resolution degradation due to axial chromatic aberration, particularly in bands with lower pixel density, and focus errors are challenging to address.
Innovation Solution
The image sensing apparatus employs a Bayer arrangement of solid-state image sensing elements with higher density in specific color filters, ensuring that focus errors due to axial chromatic aberration are within the depth of focus range, even at maximum aperture, by optimizing the f-number and spectral transmittance of the imaging lens.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a single-plate image sensor with five or more color bands is used, then the camera can capture multiple color bands simultaneously, but axial chromatic aberration causes focus errors and resolution degradation
Solution Approach 1:
The patent applies parameter changes by optimizing the f-number of the imaging lens to a specific range (F5.6 to F8.0) that balances aperture performance with axial chromatic aberration control. It also adjusts the axial chromatic aberration amount through lens design parameters to ensure focus error remains within acceptable limits across all five color bands, thereby maintaining manufacturing precision while enabling multiband capture
2Adaptability or versatility
If the pixel density varies across different color bands, then each band can be optimized for its specific requirements, but bands with lower pixel density experience resolution degradation
Solution Approach 1:
The patent implements local quality by allowing different pixel densities for different color bands on the single-plate image sensor. Each band can be optimized independently - for example, the green band can have higher pixel density for luminance information while red and blue bands have lower density for chrominance information. The axial chromatic aberration control ensures that even bands with lower pixel density maintain sufficient resolution by keeping focus errors within the depth of focus range
3Use of energy by moving object
If a larger aperture is used, then light gathering capability improves, but focus errors due to axial chromatic aberration increase
Solution Approach 1:
The patent resolves this contradiction by optimizing the f-number parameter to a specific range (F5.6 to F8.0). This parameter setting allows the lens to maintain sufficient light gathering capability while keeping the axial chromatic aberration-induced focus error within the depth of focus range. The lens design also optimizes other parameters such as focal length and optical structure to further control chromatic aberration across the aperture range
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 configuration maintains high resolution across all bands by minimizing focus errors, allowing for sharper images and practical use even with larger apertures, unlike conventional multiband cameras which require smaller apertures to compensate for focus errors.
Implementation Method 1
solid-state image sensing element 1 to solid-state image sensing element N which are different in the color to be sensed
Implementation Method 2
a focus error amount due to an axial chromatic aberration of the imaging lens
Data Source
AI summary
Solid-state image sensing elements p and q arranged on an image sensor at a higher density than other solid-state image sensing elements are configured so that the focus error amount due to the axial chromatic aberration of an imaging lens between the solid-state image sensing elements p and q is equal to or larger than an amount corresponding to the depth of focus in a maximum aperture. Also, the imaging lens has a f-number which allows the focus error amount to fall within the range between the two ends of the depth of focus.