Variable Magnification Lens Layout for Compact Aberration Correction
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Solution Overview
Problem
Existing optical systems with large aperture ratios face challenges in achieving compact size and weight reduction while effectively correcting aberrations such as spherical aberration and field curvature over the entire variable magnification range, particularly due to complex lens configurations and significant changes in total lens length.
Innovation Solution
A variable magnification optical system with specific lens group arrangements and distance settings, including a first negative, second positive, and third positive lens groups, where the distances between these groups change appropriately during magnification to maintain a large aperture ratio and correct aberrations, while minimizing the movement of the first lens group to achieve a compact and lightweight design.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If complex lens configurations are employed to correct various aberrations such as spherical aberration and field curvature in optical systems with bright F numbers, then aberration correction is improved, but device complexity increases and downsizing becomes difficult
Solution Approach 1:
The optical system is divided into multiple lens groups (first lens group with negative refractive power, second lens group with positive refractive power, third lens group with positive refractive power, and image surface side lens group) that can move independently during variable magnification. This segmentation allows each group to contribute specifically to aberration correction while maintaining overall system compactness.
Solution Approach 2:
The optical system employs dynamic adjustment of air distances between lens groups during variable magnification from wide-angle to telephoto end. The air distance between the first and second lens groups decreases, the air distance between the second and third lens groups changes, and the air distance between the third lens group and image surface side lens group increases, enabling adaptive aberration correction across different focal lengths.
2Length of stationary object
If the total lens length remains constant during variable magnification, then mechanical strength and compactness are improved, but field curvature deteriorates at intermediate focal length and chromatic aberrations degrade at telephoto end
Solution Approach 1:
The optical system dynamically adjusts the air distances between lens groups during variable magnification while maintaining a relatively constant total lens length. Specifically, the air distance between the first and second lens groups decreases, the air distance between the second and third lens groups changes, and the air distance between the third lens group and image surface side lens group increases, enabling adaptive aberration correction across different focal lengths.
Solution Approach 2:
The system changes the air distances between lens groups as key parameters during variable magnification. The conditional expressions define specific ranges for these distance changes: 0.03 < (D12W-D12T)/(D34T-D34W) < 0.15, 0.08 < (D23W-D23T)/(D34T-D34W) < 0.25, and 0.30 < D23N/(D34W+D34T) < 0.50, ensuring optimal aberration correction while maintaining compact form factor.
3Manufacturing precision
If significant change in total lens length is allowed during variable magnification, then aberration correction is improved, but mechanical strength and weight reduction become difficult
Solution Approach 1:
The optical system is divided into multiple lens groups that can move independently during variable magnification. This segmentation allows the first lens group to be minimized in movement while other groups adjust, reducing the overall weight and mechanical complexity required for magnification control.
Solution Approach 2:
The system optimizes the conditional expressions for air distance changes to achieve effective aberration correction with minimal movement of the first lens group. The ratios of distance changes are constrained within specific ranges, enabling compact and lightweight design while maintaining correction performance across the variable magnification range.
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 system achieves a compact and lightweight design with effective aberration correction across the entire magnification range, ensuring mechanical strength and dustproof performance by optimizing lens group distances and minimizing the first lens group's movement.
Implementation Method 1
a first lens group G1 having a negative refractive power, a second lens group G2 having a positive refractive power, a third lens group G3 having a positive refractive power
Data Source
AI summary
A variable magnification optical system that is relatively compact while suppressing various aberrations such as spherical aberration and field curvature over the entire variable magnification range. The variable magnification optical system includes, in order from the object side, a first lens group G1 having a negative refractive power, a second lens group G2 having a positive refractive power, a third lens group G3 having a positive refractive power, and an image surface side lens group GR. During variable magnification from the wide-angle end to the telephoto end, the air distance between the first lens group G1 and the second lens group G2 decreases, the air distance between the second lens group G2 and the third lens group G3 changes, and the air distance between the third lens group G3 and the image surface side lens group GR increases. The variable magnification optical system satisfies predetermined conditional expressions.