Zoom Lens Aberration Correction via Group Spacing and Abbe Number Control
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Solution Overview
Problem
Conventional zoom lenses for digital cameras lack high magnification, wide angle of view, and small f-number at the telephoto end, with existing lenses having insufficient angle of view and large f-number at the telephoto end.
Innovation Solution
A zoom lens configuration comprising a first lens group with a positive refractive power, a second lens group with a negative refractive power, a stop, a third lens group with a positive refractive power, and a fourth lens group with a negative refractive power, where the first to fourth lens groups move independently to adjust distances between them, and the third lens group includes specific lens arrangements to satisfy Abbe number conditions, allowing for high magnification and wide angle of view with a small f-number at the telephoto end.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of stationary object
If a conventional five-group type zoom lens is used, then the entire length of the zoom lens is kept relatively short, but the angle of view is not wide enough and the f-number at the telephoto end is large
Solution Approach 1:
The zoom lens is divided into five lens groups (G1 to G5) with alternating positive and negative refractive powers, where each group serves specific optical functions. The third lens group G3 is further segmented into multiple lenses (L31 to L35) with different refractive powers and Abbe numbers to independently control aberrations and light gathering capability
Solution Approach 2:
Different regions of the optical system are assigned specific properties: the first lens group G1 uses a negative meniscus lens with high dispersion to control chromatic aberration, the third lens group G3 incorporates lenses with varying Abbe numbers (νdA, νdB, νdC, νdD) to locally correct different types of aberrations, and the fourth lens group G4 uses a negative lens to control field curvature and distortion
2Reliability
If the third lens group includes multiple lenses with specific Abbe number differences, then aberration correction is improved, but the device complexity increases
Solution Approach 1:
The patent specifies precise parameter ranges for the lenses in the third lens group G3, including Abbe number differences (25 < νdD - νdA < 70, 35 < νdB - νdC < 70, 35 < νdB - νdA < 70) and focal length ratios (2.5 < f1/f3 < 8, -8 < f1/f2 < -4). These parameter constraints enable systematic aberration correction while maintaining manufacturability
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 provides a zoom lens with high magnification, wide angle of view, and small f-number at the telephoto end, effectively correcting aberrations while maintaining a compact lens length, as demonstrated by the examples achieving angles of view over 80° and f-numbers of 3.0 or less.
Implementation Method 1
a first lens group having a positive refractive power, a second lens group having a negative refractive power, a stop, a third lens group having a positive refractive power, a fourth lens group having a negative refractive power, and a fifth lens group having a positive refractive power
Data Source
AI summary
A zoom lens includes, in order from the object side, a positive first group, a negative second group, a stop, a positive third group, a negative fourth group, and a positive fifth group. During magnification change from the wide-angle end to the telephoto end, the first to fourth groups are moved to always increase the distance between the first and second groups, always decrease the distance between the second and third groups, and change the distance between the third and fourth groups and the distance between the fourth and fifth groups. The third group includes, in order from the object side, at least a positive lens, a positive lens, a negative lens, and a positive lens, and satisfies condition expression (1) below:25<νdD−νdA<70 (1),where νdA and νdD are Abbe numbers at the d-line of the most object-side lens A and the most image-side lens D.