Multi-Group Zoom Lens for Large Aperture and Aberration Correction
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Solution Overview
Problem
Existing zoom lenses face challenges in achieving a compact size, high optical performance, high-speed zoom operation, and large aperture ratio while effectively correcting various aberrations such as chromatic aberration and astigmatism.
Innovation Solution
The zoom lens design includes a first lens unit with positive refractive power that remains fixed during zooming, a second lens unit with negative refractive power, and a rear group with multiple lens units that move during zooming, adhering to specific inequalities to optimize lens arrangements and distances, thereby facilitating high magnification variation, large aperture ratio, and high image quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the zoom lens uses a conventional structure with moving lens units during zooming, then the magnification variation ratio can be increased, but the lens size and weight increase, slowing down zoom operation speed
Solution Approach 1:
The patent inverts the conventional zoom lens design by making the first lens unit (with positive refractive power) fixed during zooming, while the second lens unit (with negative refractive power) and subsequent lens units move. This inversion allows the magnification variation to be achieved primarily through the movement of the negative power lens unit, which has smaller diameter and mass, thereby increasing zoom operation speed while maintaining high magnification variation ratio.
Solution Approach 2:
The zoom lens is segmented into distinct functional groups: a fixed first lens unit and a movable second lens unit with at least four subsequent lens units. This segmentation allows independent optimization of each group's function, enabling the negative power lens unit to handle magnification variation while the positive power lens unit maintains optical performance, achieving both high-speed operation and compact size.
2Speed
If the zoom lens reduces the number of lenses to achieve compact size and high-speed operation, then the zoom operation speed improves, but the ability to correct aberrations deteriorates
Solution Approach 1:
The patent applies local quality by assigning different refractive powers to different lens units: the first lens unit has positive refractive power while the second lens unit has negative refractive power. This local differentiation allows each lens unit to contribute specifically to correcting certain types of aberrations, maintaining high image quality and aberration correction performance even with a reduced total number of lenses.
3Use of energy by moving object
If the zoom lens increases the aperture ratio, then the light gathering ability improves, but the lens diameter and overall size increase
Solution Approach 1:
The patent employs asymmetric design in the lens unit configuration, with the first lens unit having positive refractive power and the second lens unit having negative refractive power. This asymmetric arrangement allows the lens system to achieve large aperture ratio and high light gathering ability while maintaining compact overall size, as the negative power lens unit can be designed with smaller diameter compared to conventional symmetric designs.
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 enables high-speed zoom operations with improved aberration correction, particularly in lateral chromatic aberration and astigmatism, while maintaining a compact size and large aperture ratio.
Implementation Method 1
a first lens unit L1 having positive refractive power
Implementation Method 2
a second lens unit L2 having negative refractive power
Data Source
AI summary
A zoom lens includes, in order from an object side to an image side, a first lens unit having positive refractive power, a second lens unit having negative refractive power, and a rear group including at least four lens units that move during zooming. Distances between adjacent lens units change during zooming. The first lens unit is fixed relative to an image plane during zooming and during focusing. The first lens unit includes at least three lenses having positive refractive powers. A predetermined condition is satisfied.