Zoom Lens Configuration for Compact Imaging and Wide Aperture
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Solution Overview
Problem
Existing zoom lenses fail to simultaneously achieve a wide angle of field, small size, large aperture, and high zoom ratio, requiring precise settings of refractive power and lens configuration to meet these criteria.
Innovation Solution
A zoom lens configuration with a first lens unit having negative refractive power, a second lens unit with positive refractive power, and a third lens unit with negative refractive power, where the second and third lens units are positioned on the object side at the telephoto end compared to the wide angle end, and the third lens unit moves during focusing, while satisfying specific conditional expressions for refractive power and focal length ratios.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If a three-unit zoom lens configuration is used to achieve wide angle and small size, then the angle of field increases and lens size decreases, but the aperture ratio and zoom ratio cannot be simultaneously optimized
Solution Approach 1:
The patent applies parameter changes by precisely controlling the refractive powers of each lens unit and their relative positions. Specifically, it sets the refractive power of the first lens unit within -0.05 to -0.02 times the square of the focal length at the wide-angle end, and the second lens unit within 0.1 to 0.4 times the square of the focal length. These parameter optimizations enable the lens to achieve both compact size and high performance with wide angle (80° or more) and large aperture (F1.8 or smaller) simultaneously.
2Adaptability or versatility
If lens units are moved during zooming to change spacing, then zoom ratio increases, but the moving amount and complexity of the mechanism increase
Solution Approach 1:
The patent implements dynamics by enabling the third lens unit to move not only during zooming but also during focusing operations. This dynamic capability allows a single lens unit to serve dual functions: contributing to zoom ratio adjustment by changing spacing between lens units, and enabling focusing by adjusting the position of the third lens unit relative to the image plane. This reduces the need for separate focusing mechanisms and simplifies the overall system.
3Length of moving object
If the second and third lens units are positioned on the object side at telephoto end, then compactness is improved, but aberration correction becomes more difficult
Solution Approach 1:
The patent applies local quality by assigning specific optical characteristics to each lens unit. The first lens unit is designed with negative refractive power to provide wide-angle coverage and initial aberration correction. The second lens unit with positive refractive power serves as the variable magnification lens unit for zooming. The third lens unit with negative refractive power handles focusing and additional aberration correction. This localized optimization of each unit's properties enables compact telephoto positioning while maintaining aberration correction performance.
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
This configuration allows for a compact, high-performance zoom lens with a wide angle of field and small F-number, maintaining a high zoom ratio and reducing the moving amount of lens units during zooming, thus achieving a compact and bright imaging system.
Implementation Method 1
a first lens unit L1 having a negative refractive power, a second lens unit L2 having a positive refractive power, and a third lens unit L3 having a negative refractive power in this order from an object side to an image side
Data Source
AI summary
A zoom lens includes first, second, and third lens units respectively having negative, positive, and negative refractive powers in this order from an object side to an image side. The lens units move during zooming such that the spacing between adjacent lens units changes, the second and third lens units are positioned on the object side at a telephoto end when compared to a wide angle end, and the third lens unit moves during focusing. A lateral magnification of the second lens unit at the wide angle end, a lateral magnification of the second lens unit at the telephoto end, a lateral magnification of the third lens unit at the wide angle end, a lateral magnification of the third lens unit at the telephoto end, a focal length of the first lens unit, and a focal length of the second lens unit are appropriately set.