Imaging Lens System Aberration Correction via Segmented Groups
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Solution Overview
Problem
Current imaging lens systems, particularly large-diameter medium telephoto lenses, face challenges in achieving high optical performance across the entire imaging-distance range due to uncorrected aberrations such as chromatic aberration, spherical aberration, and field curvature, which affect image resolution and flatness.
Innovation Solution
The proposed imaging lens system consists of a configuration with a first lens group and a second lens group, where the second lens group includes a focus lens group that moves during focusing, and both groups are divided at a position of a maximum air gap, satisfying specific conditional expressions to optimize refractive power and curvature radii, ensuring proper correction of aberrations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a large-diameter lens with small F-number is used to enhance performance and obtain images using blurring, then image quality is improved, but chromatic aberration and field curvature increase and cannot be sufficiently corrected
Solution Approach 1:
The lens system is divided into multiple lens groups with different refractive powers and dispersion characteristics. The first lens group has positive refractive power with specific dispersion properties, while the second lens group has negative refractive power, allowing independent optimization of each group to correct chromatic aberration and field curvature while maintaining large aperture performance
Solution Approach 2:
The patent applies specific conditional expressions that define parameter ranges for focal lengths, Abbe numbers, and curvature radii. By controlling parameters such as fL1/f within -2.0 to -0.95 and NdP1Gmin_νd/L1_νd within 1.7 to 2.5, the system optimizes the balance between aperture size and aberration correction
2Ease of manufacture
If post processing is used to correct chromatic aberration, then image processing can be simplified, but optical performance with higher resolution cannot be achieved
Solution Approach 1:
The optical system performs preliminary correction of chromatic aberration and field curvature through its lens design before image capture. By pre-correcting these aberrations optically, the system ensures high resolution is achieved at the optical level, eliminating the need for post-processing correction while maintaining maximum image quality
3Adaptability or versatility
If a medium telephoto lens system with slightly long focal length is designed, then telephoto performance is achieved, but high optical performance cannot be obtained over the whole screen unless aberrations are properly corrected
Solution Approach 1:
The lens system employs asymmetric design in the arrangement and power distribution of lens groups. The first lens group with positive power and the second lens group with negative power are positioned and sized asymmetrically to optimize correction of aberrations across the entire screen, ensuring uniform high optical performance throughout the image area
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 effectively corrects aberrations like chromatic aberration, spherical aberration, and field curvature, achieving excellent optical performance with high image flatness and reduced lens system size, suitable for digital single-lens reflex cameras.
Implementation Method 1
a first lens group G1 having a positive refractive power, and a second lens group G2 having a positive refractive power
Implementation Method 2
chromatic aberration can be corrected by post processing of image processing performed in the camera or performed by software of a personal computer through image processing
Data Source
AI summary
An imaging lens system includes sequentially from an object side, a first lens group and a second lens group. The second lens group includes a focus lens group configured to move during focusing or the first lens group and the second lens group are divided at a position of a maximum air gap. Conditional Expressions (1) and (2) are satisfied as follows:−2.0<fL1/f<−0.95, and (1)1.7<NdP1Gmin_νd/L1_νd<2.5, (2)wherefL1 is a focal length of a lens located closest to the object side of the first lens group,f is a focal length of a whole system,NdP1Gmin_νd is an Abbe number for a d-line of a positive lens having a smallest refractive index of the first lens group, andL1_νd is an Abbe number for the d-line of the lens located closest to the object side of the first lens group.