Rear-Focusing Optical System Comatic Aberration Correction
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Solution Overview
Problem
Rear-focusing lenses in existing optical systems fail to adequately correct comatic aberration, particularly in larger diameter lenses, which leads to issues with spherical aberration, sagittal comatic aberration, field curvature, and astigmatism.
Innovation Solution
An optical system comprising a first lens group with a positive refractive power that remains fixed and a second lens group with a positive refractive power that moves, featuring a meniscus lens with a convex surface facing the object side, a negative lens, and a cemented lens with specific curvature relationships and refractive indices, along with anti-reflection films to reduce ghosting and flare.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If rear-focusing lenses are used in optical systems, then the system can achieve focusing functionality, but comatic aberration cannot be corrected to a sufficient extent
Solution Approach 1:
The optical system divides the lens structure into multiple lens groups (first lens group with positive refractive power and second lens group with negative refractive power), each containing specific sub-lenses (meniscus lens, negative lens, positive lens). This segmentation allows independent optimization of each group to correct comatic aberration while maintaining focusing functionality.
Solution Approach 2:
The patent applies specific design characteristics to different parts of the optical system: the meniscus lens has a convex surface facing the object side with specific curvature radius ratios, the negative lens has optimized thickness and curvature, and the positive lens has specific refractive index and Abbe number ranges. These localized quality specifications enable effective comatic aberration correction in each region.
2Reliability
If the number of lens components is increased to correct aberrations, then aberration correction improves, but the device becomes more complex and larger
Solution Approach 1:
Each lens component in the optical system serves multiple functions: the meniscus lens not only provides positive refractive power but also helps correct spherical aberration and comatic aberration; the negative lens corrects field curvature and astigmatism while contributing to overall aberration balance; the positive lens with specific material properties corrects chromatic aberration. This multi-functionality reduces the need for additional components.
Solution Approach 2:
The patent optimizes specific parameters of each lens component to achieve maximum aberration correction with minimal components. This includes curvature radius ratios of the meniscus lens (0.2 < r1/r2 < 1.0), thickness ratios, refractive indices (1.50 < N2 < 1.70), and Abbe numbers (30 < ν2 < 60) of the negative lens, and refractive indices (1.70 < N3 < 1.90) and Abbe numbers (20 < ν3 < 40) of the positive lens. These parameter optimizations enable effective aberration control without increasing component count.
3Reliability
If lens surfaces are optimized for aberration correction, then optical performance improves, but manufacturing precision requirements increase
Solution Approach 1:
The patent focuses optimization efforts on the most critical lens surfaces that have the greatest impact on aberration correction. Specifically, the meniscus lens surfaces with convex object-side orientation, the negative lens with optimized thickness, and the positive lens with specific material properties receive primary optimization attention. This partial action approach achieves effective aberration correction without requiring extreme precision across all lens surfaces.
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 solution effectively corrects comatic aberration, sagittal comatic aberration, and spherical aberration while maintaining optimal performance without exacerbating chromatic aberration or field curvature, using a minimal number of components and reducing ghosting and flare through the use of anti-reflection films.
Implementation Method 1
anti-reflection films to reduce ghosting and flare
Implementation Method 2
at least one meniscus lens with a convex surface thereof facing the object side
Implementation Method 3
at least one negative lens disposed toward the image surface relative to the meniscus lens
Implementation Method 4
a cemented lens that is disposed on the image surface side of the second partial lens group, is formed by bonding together a plurality of lenses and has a positive refractive power
Data Source
AI summary
An optical system includes, disposed in sequence along an optical axis starting on an object side: a first lens group having a positive refractive power, which remains fixed relative to an image surface upon focusing; and a second lens group having a positive refractive power, which moves along the optical axis upon focusing, wherein: the first lens group includes: a first partial lens group that comprises at least two positive lenses and has a positive refractive power; and a negative lens, the second lens group includes: at least one meniscus lens with a convex surface thereof facing the object side; a second partial lens group that includes at least one negative lens and at least one positive lens, and has a positive refractive power; and a cemented lens that is formed by bonding together a plurality of lenses and has a positive refractive power, wherein: a predetermined conditional expression is satisfied.