Zoom Lens Fourth Unit Aberration Correction
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Solution Overview
Problem
Conventional four-unit zoom lenses face challenges in achieving high optical performance over the entire zoom range due to difficulties in correcting lateral chromatic aberration and off-axis aberrations at the wide-angle end, while increasing the number of lenses complicates manufacturing and system size.
Innovation Solution
A zoom lens configuration with specific refractive power distributions and lens group arrangements, including a first lens unit with positive refractive power that does not move, a second and third lens unit with negative and positive refractive power that move during zooming, and a fourth lens unit with positive refractive power that does not move, optimized by dividing the fourth lens unit into three groups with precise air intervals and material selection to satisfy specific conditions for aberration correction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the number of lenses in each lens unit is increased to correct off-axis aberrations, then optical performance is improved, but system size and manufacturing complexity increase
Solution Approach 1:
The patent applies local quality by concentrating aberration correction functions in specific lens units rather than distributing them uniformly. The fourth lens unit is specifically designed with a three-group structure (41, 42, 43) where each group has optimized refractive powers and material characteristics tailored to correct specific aberrations at the wide-angle end, while maintaining overall system compactness.
Solution Approach 2:
The patent utilizes parameter changes by precisely controlling the refractive powers, air intervals, and material properties (Abbe constants and partial dispersion ratios) of the lens groups. The conditions on β3w, f4, Ld4, and the ratios involving f42, ν42p, θ42p, ν42n, and θ42n demonstrate optimized parameters that achieve high optical performance without increasing system size.
2Reliability
If optical materials with anomalous dispersion are used to correct lateral chromatic aberration, then chromatic aberration correction is improved, but manufacturing precision requirements increase
Solution Approach 1:
The patent employs composite materials by combining lens groups with different material characteristics in the fourth lens unit. The structure includes positive and negative lens groups with specific Abbe constants and partial dispersion ratios, creating a composite optical system that corrects lateral chromatic aberration through the synergistic effect of multiple materials with complementary dispersion properties.
3Reliability
If the fourth lens unit is designed with appropriate configuration and material settings to correct lateral chromatic aberration at the wide-angle end, then optical performance over entire zoom range is improved, but design complexity increases
Solution Approach 1:
The patent applies segmentation by dividing the fourth lens unit into three distinct lens groups (41, 42, 43) with specific refractive power distributions. This segmentation allows each group to perform specialized functions: the 41 group handles primary focusing, the 42 group corrects chromatic aberrations through its negative refractive power, and the 43 group fine-tunes the image quality, thereby achieving comprehensive aberration correction through modular design.
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 enables a zoom lens with a wide angle of field and high zoom ratio, effectively correcting various aberrations over the entire zoom range while maintaining a compact and lightweight design, achieving high optical performance and reducing aberration variations.
Implementation Method 1
a first lens unit which does not move for zooming and has a positive refractive power, a second lens unit which moves during zooming and has a negative refractive power, a third lens unit which moves during zooming and has a positive refractive power, and a fourth lens unit which does not move for zooming and has a positive refractive power
Implementation Method 2
The lateral chromatic aberration is easily well corrected by using an optical material having anomalous dispersion. However, it is difficult to well correct a chromatic aberration even by simply using a lens made of an optical material having anomalous dispersion
Data Source
AI summary
In a zoom lens including a positive first lens unit, negative second lens unit, positive third lens unit, and positive fourth lens unit, the fourth lens unit includes a 41 lens group, a 42 lens group, and a 43 lens group. the lateral magnification of the third lens unit at a wide-angle end when an infinite object is focused, the focal length of the fourth lens unit, the lens configuration length of the fourth lens unit, the air interval between the 41 and 42 lens groups, the air interval between the 42 and 43 lens groups, the focal length of the 42 lens group, the average values of the Abbe constants and partial dispersion ratios of positive lens of the 42 lens group, the average values of the Abbe constants and partial dispersion ratios of negative lenses of the 42 lens group, and the like are appropriately set.