Zoom Lens Optical System with Aspheric Peripheral Correction
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Solution Overview
Problem
Current imaging devices with zoom lenses face challenges in maintaining high image quality across the entire zoom range, particularly in wide-angle imaging, due to aberrations and degradation in peripheral image quality, and existing restoration processes are not effective in all situations, especially when blurring is excessive or insufficient.
Innovation Solution
An imaging device with an optical system that combines a variable focal length and a sharpening processing unit performing a restoration process based on the optical transfer function, optimizing the modulation transfer function (MTF) and restoration process to improve image quality, especially in wide-angle imaging by prioritizing the peripheral portion's quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If an aspheric lens is used to reduce the degradation of the quality of a peripheral portion of the image on the wide-angle side, then the quality of the peripheral portion is improved, but the performance of the lens on the telephoto side deteriorates with very large variation in aberration
Solution Approach 1:
The patent applies aspheric lenses specifically at strategic positions within the optical system to correct peripheral image quality on the wide-angle side without requiring the entire lens system to be aspheric. This localized application of aspheric surfaces improves peripheral resolution while maintaining acceptable telephoto performance.
Solution Approach 2:
The optical system combines multiple lens materials with different refractive indices and dispersion characteristics, including aspheric and spherical lenses, to achieve a balance between wide-angle peripheral quality and telephoto stability. This composite approach allows compensation of aberrations across the zoom range.
2Area of moving object
If the focal length of the optical system is shortened to achieve wide-angle imaging, then the angle of view is widened, but the image quality degradation increases
Solution Approach 1:
The patent employs a zoom lens system with variable focal length that dynamically adjusts optical parameters across the zoom range. The optical system is designed to maintain acceptable image quality at different focal lengths by coordinating the movement of multiple lens groups, allowing wide-angle imaging while managing quality degradation through dynamic optical adjustment.
3Manufacturing precision
If a restoration process based on optical transfer function is applied to an image with excessively large amount of blurring, then the processing complexity increases, but the image quality improvement is insufficient
Solution Approach 1:
The restoration process dynamically adjusts processing parameters based on the measured amount of blurring in the input image. When blurring is within an effective range, the optical transfer function-based restoration is applied with appropriate strength; when blurring is excessive, the processing intensity is reduced or alternative methods are used, avoiding unnecessary computational complexity while maintaining image quality improvement where beneficial.
Data Source
AI summary
An optical system has the entire angle of view at a wide-angle end of not smaller than 90 degrees. A spatial frequency at which an MTF of the optical system acquired using an evaluation wavelength in a region of an image formation plane in which the distance from the center of the image formation plane is not less than 80% and less than 95% of half of the length of a diagonal line of an imaging surface of an imaging element image is not more than 30% is higher at the wide-angle end than at a telephoto end. When F≥√(Fw×Ft) is satisfied (where F indicates the focal length of the optical system when the target image is captured, Fw indicates the focal length at the wide-angle end, and Ft indicates the focal length at the telephoto end), a sharpening processing unit performs a restoration process based on an optical transfer function of the optical system as a sharpening process.