Four-Group Zoom Lens with Cemented Negative-Positive Element
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Solution Overview
Problem
Current zoom lenses for video and electronic still cameras face challenges in achieving higher magnification and zoom ratios while maintaining compactness and ultra-high image quality.
Innovation Solution
A zoom lens configuration comprising a first lens group with positive refractive power, a second lens group with negative refractive power, a third lens group with positive refractive power, and a fourth lens group with positive refractive power, where the first lens group includes a cemented negative lens and a positive meniscus lens, and all groups move together with an aperture stop, satisfying specific Abbe number and focal length conditional expressions to correct aberrations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If zoom ratio and magnification are increased, then imaging capability is improved, but lens structure becomes more complex and compactness deteriorates
Solution Approach 1:
The lens is divided into four distinct lens groups (G1, G2, G3, G4) with specific refractive powers, allowing independent movement and control of each group to achieve high zoom ratio while managing structural complexity through modular design
Solution Approach 2:
All four lens groups are designed to move dynamically during zooming operations, with the aperture stop moving together with the third lens group, enabling flexible focal length adjustment and maintaining compactness through coordinated motion
2Adaptability or versatility
If higher magnification is achieved, then imaging capability is improved, but aberration correction becomes more difficult
Solution Approach 1:
Each lens group is designed with specific local optical characteristics - G1 has positive refractive power for light gathering, G2 has negative refractive power for aberration correction, G3 has positive refractive power for focusing, and G4 has positive refractive power for final image formation, with each group optimized for its specific function
Solution Approach 2:
The lens employs a composite structure combining multiple lens materials with different refractive indices and dispersion characteristics, including cemented lenses and meniscus lenses, to achieve both high magnification and effective aberration correction across the spectral range
3Adaptability or versatility
If lens groups are increased for higher zoom ratio, then magnification is improved, but lens barrel length increases and compactness deteriorates
Solution Approach 1:
The lens groups are arranged in a nested configuration where G2 is positioned between G1 and G3, and G4 is positioned after G3, with the aperture stop integrated into the G3 assembly, allowing compact packaging of multiple functional elements within a reduced overall lens barrel length
Solution Approach 2:
The lens design utilizes three-dimensional spatial arrangement and depth positioning of lens groups, with varying object-side and image-side distances, to achieve high zoom ratio functionality within a compact axial length by exploiting the third dimension of optical space
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 higher zoom ratio, compactness, and ultra-high image quality with effective correction of lateral chromatic and spherical aberrations, achieving high magnification and improved image forming performance across various focal length states.
Implementation Method 1
a first lens group having positive refractive power; a second lens group having negative refractive power, a third lens group having positive refractive power; and a fourth lens group having positive refractive power
Implementation Method 2
the first lens group includes only, in order from the object, a cemented lens of a negative lens and a positive lens
Data Source
AI summary
Provided is a zoom lens, including, in order from an object: a first lens group (G1) having positive refractive power; a second lens group (G2) having negative refractive power; a third lens group (G3) having positive refractive power; and a fourth lens group (G4) having positive refractive power. The first lens group (G1 includes only, in order from the object, a cemented lens of a negative lens (L11) and a positive lens (L12), and a positive meniscus lens (L13) having a convex surface facing the object, an aperture stop (S) for determining brightness is disposed to the object side of the third lens group (G3), and upon zooming, all of the four groups (G1 to G4) move and the aperture stop (S) moves together with the third lens group (G3), and the conditional expression νdp1>85.0 is satisfied, where νdp1 denotes an Abbe number of the positive lens (L12), which is disposed closest to the object in the first lens group (G1), at the d-line as a standard.