Zoom Lens Aberration Control via Dynamic Group Spacing
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Solution Overview
Problem
Existing zoom lenses for medium telephoto zones face issues with aberration fluctuations, size constraints, and limited zoom ratios due to strong refracting power and interference between lens groups, making it difficult to achieve both size reduction and high zoom ratios while maintaining optical performance.
Innovation Solution
A zoom lens design with a first lens group of positive refracting power, a second lens group of negative refracting power, and a third lens group, where an aperture stop is located between the second and third lens groups, allowing the first and second lens groups to move in unison with varying spacings to maintain short length and balance aberrations, while satisfying specific focal length and movement conditions to optimize zoom ratios and optical performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the first lens group is made thick with strong refracting power to control aberrations, then aberration control is improved, but the overall lens size increases and zoom ratio is limited
Solution Approach 1:
The first lens group is divided into multiple lens elements (first through fourth lenses) with different refracting powers and characteristics. This segmentation allows each element to contribute differently to aberration correction while maintaining a more compact overall structure compared to a single thick lens with strong refracting power.
Solution Approach 2:
Different lens elements within the first lens group are assigned different local properties: the first lens has positive refracting power with specific curvature characteristics, the second lens has negative refracting power, the third lens has positive refracting power, and the fourth lens has negative refracting power. This local differentiation optimizes aberration control in various regions of the optical path without requiring excessive overall thickness.
2Adaptability or versatility
If the spacing between lens groups is increased to achieve higher zoom ratios, then zoom ratio is improved, but the overall lens length increases reducing portability
Solution Approach 1:
The lens groups are designed with dynamic movement capabilities during zooming operations. The first and second lens groups move in unison along the optical axis, while the third lens group moves independently. This dynamic coordination allows the spacing between lens groups to vary optimally throughout the zoom range, achieving high zoom ratios (3.1x or higher) while controlling the maximum overall lens length to maintain portability.
3Length of moving object
If the second and third lens groups are positioned close together to shorten lens length, then lens compactness is improved, but interference between lens groups occurs reducing optical performance
Solution Approach 1:
The spacing between the second and third lens groups is made dynamic rather than fixed. During zooming operations, the third lens group moves independently relative to the second lens group, maintaining an optimal non-interfering distance when needed while allowing compact positioning when the optical design requires it. This dynamic adjustment prevents harmful interference while enabling lens compactness.
Solution Approach 2:
The aperture stop is positioned between the second and third lens groups, serving as an intermediary element. This positioning helps define the optical path and reduces potential interference between the second and third lens groups by controlling the cone of light passing through the system, allowing closer spacing without sacrificing optical performance.
4Reliability
If the first lens group moves independently to correct aberrations, then optical performance is improved, but device complexity increases
Solution Approach 1:
The first and second lens groups are coupled to move in unison along the optical axis during zooming operations, sharing a common movement mechanism. This merging of movement reduces the number of independent drive mechanisms required, lowering device complexity. Meanwhile, the third lens group moves independently to provide the necessary degrees of freedom for aberration correction and focus control, achieving optical performance improvement without excessive 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 design achieves a compact zoom lens that supports higher zoom ratios and improved optical performance by balancing lens group movements and refracting powers, reducing aberrations and maintaining a short length, thus enhancing the camera's portability and usability.
Implementation Method 1
a first lens group having positive refracting power
Implementation Method 2
a second lens group having negative refracting power
Implementation Method 3
a third lens group having positive refracting power
Data Source
AI summary
The invention relates to a zoom lens in which tweaks to the mode of movement of lens groups and the first lens group contribute more to making sure the desired zoom ratio and optical performances and ensuring that the whole length of the zoom lens is kept short while carrying it around. The zoom lens comprises a positive first lens group G1, a negative second lens group G2 and a positive third lens group G3, and includes an aperture stop S located between the second G2 and the third lens group G3. Upon zooming from the wide-angle end to the telephoto end, the first lens group G1 moves in unison, and the second lens group G2 moves in unison. The first G1 and the second lens group G2 are positioned nearer to the object side at the telephoto end than at the wide-angle end, with an increasing spacing between the first G1 and the second lens group G2 and a decreasing spacing between the second G2 and the third lens group G3. The zoom lens satisfies conditions (1) and (2) about the power and the amount of movement of the first lens group G1.