Zoom Lens Cemented Groups Chromatic Aberration Correction
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Solution Overview
Problem
Conventional zoom lenses face challenges in effectively correcting chromatic aberration across the entire zoom range, particularly with the second and third lens groups, which affects the optical performance and image quality.
Innovation Solution
A zoom lens configuration with specific cemented lens groups and refractive power distributions, including A, B, and C cemented lenses, is used, where the Abbe numbers and partial dispersion ratios of the lenses are optimized to satisfy certain condition expressions, allowing for balanced correction of primary and secondary chromatic aberrations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a material having low dispersion and high abnormal dispersion is used to form a positive lens in the first lens group, then primary chromatic aberration is corrected, but secondary chromatic aberration becomes significant
Solution Approach 1:
The patent employs composite lens structures where a positive lens and negative lens are cemented together to form a cemented lens. The positive lens uses material with low dispersion and high abnormal dispersion, while the negative lens uses material with high dispersion. This composite structure allows the positive lens to correct primary chromatic aberration while the negative lens compensates for secondary chromatic aberration, achieving balanced correction of both aberration types.
2Measurement precision
If multiple cemented lenses are added to correct chromatic aberration in the second and third lens groups, then chromatic aberration variation is reduced, but device complexity increases
Solution Approach 1:
The patent applies chromatic aberration correction locally at specific positions within the lens system. A cemented lens is strategically placed in the second lens group (which has strong magnification changing effect) and another cemented lens is placed in the third lens group (which has negative refractive power). This localized approach targets the specific lens groups that contribute most to chromatic aberration variation, achieving effective correction without uniformly increasing complexity throughout the entire lens system.
3Ease of manufacture
If the second lens group uses material with low dispersion but not high abnormal dispersion, then manufacturing is easier, but secondary chromatic aberration cannot be suppressed
Solution Approach 1:
The patent creates a composite lens structure where the positive lens component uses material with low dispersion and high abnormal dispersion (enabling secondary chromatic aberration suppression), while the negative lens component uses material with high dispersion. This composite approach allows the system to achieve both manufacturing feasibility and superior optical performance by combining materials with complementary properties rather than relying on a single material that would need to simultaneously satisfy all requirements.
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 proposed configuration achieves high optical performance by successfully suppressing primary and secondary chromatic aberrations across the zoom range, resulting in improved image quality with reduced aberrations.
Implementation Method 1
a zoom lens configuration with specific cemented lens groups and refractive power distributions, including A, B, and C cemented lenses, is used, where the Abbe numbers and partial dispersion ratios of the lenses are optimized to satisfy certain condition expressions, allowing for balanced correction of primary and secondary chromatic aberrations
Data Source
AI summary
A zoom lens consists of, in order from the object side, a positive first group, a negative second group, one or two middle groups including a positive mp group, and a positive rearmost group disposed at the most image-side position of the entire system. Zooming is effected by changing all distances between the adjacent groups. An A cemented lens formed by a positive lens and a negative lens which are cemented together in this order from the object side is disposed at the most object-side position of the second group, a B cemented lens formed by one positive lens and one negative lens is disposed on the image side of the A cemented lens and on the object side of the mp group, and a C cemented lens formed by one positive lens and one negative lens is disposed in the mp group. The zoom lens satisfies given condition expressions.