Five-Group Zoom Lens Layout for Compact Size and Aberration Correction
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Solution Overview
Problem
Existing zoom lenses with larger diameters face challenges in achieving a smaller size and higher optical performance, particularly in correcting aberrations such as spherical aberration, chromatic aberration, and coma aberration.
Innovation Solution
A zoom lens configuration comprising five lens groups with specific refractive powers and movements, including a fourth lens group as a focusing lens group, and satisfying conditional expressions to optimize lens thickness and magnification ratios, ensuring aberration correction and compact size.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If zoom lenses are designed with larger diameters to achieve higher optical performance, then aberration correction is improved, but the overall size of the lens increases
Solution Approach 1:
The zoom lens is divided into five distinct lens groups (G1-G5) with specific refractive powers, where each group contributes to aberration correction in a coordinated manner. The fourth lens group is further segmented to include a negative lens and a positive lens, allowing independent optimization of different aberration types while maintaining compact overall dimensions
Solution Approach 2:
Different regions of the lens system are assigned specific functions: the fourth lens group is dedicated to correcting spherical aberration and coma aberration, while the fifth lens group focuses on correcting chromatic aberration. This localized optimization allows effective aberration correction without requiring uniform increases in all lens dimensions
2Reliability
If the third lens group thickness is increased to improve aberration correction, then optical performance is enhanced, but the lens becomes larger and more complex
Solution Approach 1:
The patent optimizes the thickness parameter of the third lens group by satisfying the conditional expression 0.25 < GD3/ft < 0.65, where GD3 is the third lens group thickness and ft is the telephoto focal length. This parameter optimization achieves effective aberration correction while preventing excessive increase in lens thickness
3Reliability
If multiple lens groups are added to achieve compact size and large diameter, then optical performance is improved, but device complexity increases
Solution Approach 1:
The fourth lens group serves multiple functions: it acts as a focusing lens group that moves in the optical axis direction upon focusing, corrects spherical aberration and coma aberration, and contributes to the overall zooming mechanism. This multi-functionality reduces the need for additional dedicated components, thereby managing complexity
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 achieves a zoom lens with a large diameter and small size, effectively correcting various aberrations and ensuring excellent optical performance across different focal lengths.
Implementation Method 1
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; a fourth lens group G4 having negative refractive power; and a fifth lens group G5 having positive refractive power
Data Source
AI summary
A zoom lens comprises, 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; a fourth lens group (G4) having negative refractive power; and a fifth lens group (G5) having positive refractive power, in which the first to the fifth lens groups (G1 to G5) each move in an optical axis direction upon zooming from a wide angle end state to a telephoto end state, at least a part of the fourth lens group (G4) is configured to serve as a focusing lens group to move in the optical axis direction upon focusing, the first lens group (G1) consists of two lenses, and the following conditional expression is satisfied:0.30<GD3/ft<0.8 where, GD3 denotes a thickness of the third lens group (G3) on the optical axis, and ft denotes a focal length of the zoom lens in the telephoto end state.