Zoom Lens with Segmented Groups for Compact High-Aperture Design
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Solution Overview
Problem
Existing zoom lenses with high aperture ratios face challenges in achieving compact size and high optical performance while effectively correcting various aberrations.
Innovation Solution
A zoom lens configuration that includes a plurality of lens groups, with specific refractive power arrangements and movement trajectories during zooming and focusing, to achieve a high aperture ratio, compact size, and corrected aberrations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If a lens group having strong positive refractive power is disposed on the rear side of the optical system to achieve high aperture ratio, then the aperture ratio is improved, but the total optical length increases and the telephoto tendency is reduced
Solution Approach 1:
The optical system is divided into five lens groups (G1-G5) with alternating positive and negative refractive powers. The rear-side group G5 has positive refractive power and is disposed closest to the image plane, while middle group G3 and front group G1 provide additional positive power. This segmentation allows the aperture ratio to be improved by 0.95 or more without excessively increasing the total optical length, as the negative power groups (G2, G4) help compact the overall system.
Solution Approach 2:
Different lens groups are assigned specific refractive power characteristics tailored to their positions in the optical system. The rear-side group G5 is configured with positive refractive power to improve aperture ratio locally at the image plane side, while intermediate groups G3 and front group G1 also have positive power. This local optimization of refractive power distribution enables high aperture ratio while controlling total optical length through the balancing negative power groups.
2Reliability
If the second lens group is configured as a focus group with multiple lenses to achieve high optical performance, then the optical performance is improved, but the weight increases and quick focusing becomes difficult
Solution Approach 1:
The focusing function is distributed across multiple lens groups (G2, G4, and G5) rather than concentrating all focusing elements in a single heavy group. Each group contributes to focus adjustment through its specific movement characteristics, allowing the system to achieve high optical performance while keeping individual focus group weights manageable for quick focusing operation.
Solution Approach 2:
The patent employs dynamic focusing where different lens groups move by different amounts during focusing operation. The rear-side group G5 moves a smaller distance compared to other groups, reducing the required drive mechanism size and weight while maintaining focusing capability. This dynamic distribution of focus movement enables quick focusing without requiring a single heavy focus group.
3Productivity
If strong negative refractive power is set in the second lens group to achieve high-power zooming, then the zooming capability is improved, but the lens barrel diameter increases
Solution Approach 1:
The zooming function is distributed across multiple lens groups (G1-G5) with alternating positive and negative refractive powers. The negative power groups (G2, G4) are balanced by positive power groups (G1, G3, G5), allowing high-power zooming capability to be achieved while the overall lens barrel diameter is controlled through the compensating effect of positive power groups that reduce the required negative power magnitude.
Solution Approach 2:
Negative refractive power is strategically assigned to specific intermediate groups (G2, G4) rather than concentrating it in a single group. This local placement of negative power, balanced by positive power groups at other positions, enables high zooming capability while minimizing the maximum lens barrel diameter required to accommodate the optical elements.
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 proposed zoom lens design achieves a high-performance imaging apparatus with a high aperture ratio, compact size, and satisfactorily corrected aberrations, addressing the limitations of existing technologies.
Implementation Method 1
a lens group P having positive refractive power and a middle group M1 including one or more lens groups and having negative refractive power as a whole
Data Source
AI summary
There is provided a zoom lens configured to include an anterior group having negative refractive power as a whole and a posterior group having positive refractive power as a whole. In zooming from a wide-angle end to a telephoto end, five or less lens groups are moved to change intervals, and the zoom lens has specific optical characteristics represented by specific conditions.