Zoom Lens Compactness via High Abbe Constant Focus Group
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Solution Overview
Problem
Conventional zoom lenses face challenges in achieving a high variable magnification ratio while maintaining compactness and excellent optical performance throughout the entire focus range, particularly due to difficulties in correcting chromatic aberration at the wide-angle end and the resulting larger size from an improperly positioned aperture stop.
Innovation Solution
A zoom lens configuration with multiple lens groups that change distance between adjacent groups, featuring an aperture stop with focus groups on both sides, and a lens La with an Abbe constant greater than 60 to correct chromatic aberration, allowing for compactness and high magnification while suppressing aberration fluctuation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the aperture stop is positioned far from the image plane, then the zoom lens can achieve a high variable magnification ratio, but the rear ball diameter becomes larger making the entire zoom lens larger
Solution Approach 1:
The patent changes the material parameter (Abbe constant) of the lens in the focus group to greater than 60, which allows for correction of chromatic aberration of magnification. This parameter change enables the aperture stop to be positioned closer to the image plane (reducing rear ball diameter) while still achieving high variable magnification ratio through optimized lens group movements.
2Device complexity
If the focus group is arranged closer to the image side than the aperture stop, then the zoom lens structure is simplified, but chromatic aberration of magnification at the wide-angle end cannot be corrected
Solution Approach 1:
The patent changes the material parameter (Abbe constant) of the lens in the focus group to greater than 60, which provides the optical power needed to correct chromatic aberration of magnification. This allows the focus group to be arranged on the object side of the aperture stop while still achieving excellent correction of chromatic aberration across the entire zoom range.
3Volume of moving object
If a lens with high dispersion material is used in the focus group, then the zoom lens can be compact, but chromatic aberration of magnification at the wide-angle end deteriorates
Solution Approach 1:
The patent changes the material parameter (Abbe constant) to greater than 60, which represents a low dispersion material. This enables the zoom lens to maintain a compact size while effectively correcting chromatic aberration of magnification, as the low dispersion material reduces chromatic aberration generation in the focus group.
Solution Approach 2:
The patent uses a composite lens structure in the focus group that combines multiple lenses with different dispersion characteristics. By integrating a lens with Abbe constant greater than 60 into this composite structure, the system achieves both compactness and excellent correction of chromatic aberration of magnification through the synergistic effect of the combined lens materials.
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 enables a compact zoom lens with excellent optical performance across the entire focus range and high magnification ratio by effectively correcting chromatic aberration and maintaining a balanced aperture stop position, preventing the lens from becoming excessively large.
Implementation Method 1
the lens La satisfies the following conditional expression: 60 < νa here, νa is Abbe constant relative to the d-line of the material forming the lens La
Data Source
AI summary
A zoom lens has a plurality of lens groups and is a zoom lens that zooms from the wide-angle end to the telephoto end by changing the distance between adjacent lens groups, and has an aperture stop and at least one focus group each on the object side and the image side with the aperture stop therebetween, and when focused from infinity to a close object, the focus groups move along the optical axis, and the focus group arranged on the object side closer than the aperture stop includes at least one lens, and the lens satisfies the predetermined conditional expression. In addition, an imaging apparatus includes the zoom lens.