Zoom Lens Design with Dynamic Interval Adjustment
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Solution Overview
Problem
Existing zoom lenses face challenges in achieving high optical characteristics with a large aperture ratio and high zoom ratio while maintaining a compact size, due to inadequate settings of refractive powers and movement conditions of lens units during zooming.
Innovation Solution
A zoom lens design comprising specific refractive power configurations and interval adjustments between lens units, including a first lens unit with positive and negative sub-units, and a rear lens group with varying focal lengths and lateral magnifications, satisfying conditional expressions to optimize focal length and aperture settings across the zoom range.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If a high zoom ratio is realized with a compact size, then the system size is reduced, but it becomes difficult to obtain high optical characteristics with a large aperture ratio
Solution Approach 1:
The zoom lens is divided into multiple lens units (first lens unit with positive refractive power, second lens unit with negative refractive power, third lens unit with positive refractive power, and rear lens group) that can move independently during zooming. This segmentation allows each unit to be optimized for specific functions, enabling high optical characteristics while maintaining a compact overall structure with high zoom ratio.
Solution Approach 2:
The intervals between adjacent lens units are dynamically changed during zooming to achieve high zoom ratio while maintaining compact size. Specifically, the interval between the first and second lens units increases from wide angle to telephoto, while the interval between the second and third lens units decreases, allowing the system to achieve long focal length at telephoto end without proportionally increasing total length.
2Illumination intensity
If the aperture ratio is increased, then brightness is improved, but the system size increases
Solution Approach 1:
The first lens unit is configured with specific local qualities: it consists of a first lens sub-unit with positive refractive power and a second lens sub-unit with negative refractive power arranged over the widest air interval within the first lens unit. This local optimization of the first lens unit structure enables large aperture ratio (high brightness) while controlling the overall system size through the conditional expression 0.10 < f1a/ft < 0.60.
3Adaptability or versatility
If the focal length at telephoto end is increased, then zoom ratio is improved, but the system length increases
Solution Approach 1:
The intervals between lens units are dynamically adjusted during zooming: the interval between the first and second lens units increases, while the interval between the second and third lens units decreases from wide angle to telephoto end. This dynamic interval adjustment allows achieving long focal length at telephoto end with high zoom ratio without proportionally increasing the total system length.
Solution Approach 2:
The refractive powers of the lens units and their intervals are optimized according to specific conditional expressions (0.10 < f1a/ft < 0.60 and -0.70 < β1b/β2t < 0.20). These parameter changes enable the system to achieve high zoom ratio with extended telephoto focal length while maintaining a compact overall structure through mathematical optimization of the optical parameters.
4Reliability
If appropriate settings of refractive powers and movement conditions are achieved, then optical characteristics are improved, but the design complexity increases
Solution Approach 1:
The patent establishes specific conditional expressions (0.10 < f1a/ft < 0.60 and -0.70 < β1b/β2t < 0.20) that define the optimal ranges for refractive power ratios and lateral magnification ratios. By constraining the design parameters within these mathematically defined ranges, the patent simplifies the design process while ensuring high optical characteristics, reducing the need for extensive iterative optimization.
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 high optical characteristics with a large aperture and long focal length at the telephoto end while downsizing the entire system, effectively correcting spherical and chromatic aberrations across the entire zoom range.
Implementation Method 1
a first lens unit having a positive refractive power; a second lens unit having a negative refractive power; a third lens unit having a positive refractive power
Data Source
AI summary
Provided is a zoom lens, comprising, in order from object side to image side: first positive, second negative and third positive lens units and a rear lens group including at least one lens unit, in which: at telephoto end as compared to wide angle end, an interval between first and second lens units is increased, and an interval between second and third lens units is reduced; an interval between adjacent lens units is changed during zooming; the first lens unit consists, in order from object side to image side, of a first positive lens sub-unit, and a second negative lens sub-unit over a widest air interval; and a focal length ft of zoom lens at telephoto end, a focal length f1a of first lens sub-unit, a lateral magnification β1b of second lens sub-unit, and a lateral magnification β2t of second lens unit at telephoto end are appropriately set.