Zoom Lens Aberration Correction via Segmented Power Distribution
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Solution Overview
Problem
Conventional zoom lenses face challenges in achieving high optical performance over the entire zoom range while being compact, as size reduction leads to increased aberrations, particularly distortion and lateral chromatic aberration, and varying aberrations with zooming.
Innovation Solution
A zoom lens configuration with specific refractive power arrangements and movements of lens units, including a first lens unit with positive power, a second with negative power, a third with positive power, a fourth with negative power, a fifth with negative power, and a sixth with positive power, where the interval between adjacent lens units changes during zooming, and the first lens unit moves toward the object side, satisfying specific conditional expressions to correct aberrations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If the total lens length is reduced to make the zoom lens compact, then the size is reduced, but distortion and lateral chromatic aberration are generated more greatly
Solution Approach 1:
The zoom lens is divided into six lens units with alternating positive and negative refractive powers, where each lens unit can move independently during zooming. This segmentation allows precise control of optical path and aberration correction while maintaining a compact overall structure, resolving the contradiction between size reduction and aberration control.
Solution Approach 2:
The patent employs variable interval settings between adjacent lens units during zooming, and satisfies specific conditional expressions for focal length ratios and back focus distances. These parameter optimizations enable effective aberration correction in a compact lens design, addressing the contradiction between reduced size and maintained optical performance.
2Length of stationary object
If retrofocus-type power arrangement is made at wide angle end to reduce back focus length, then the lens length is reduced, but distortion and lateral chromatic aberration increase
Solution Approach 1:
The wide angle end employs a segmented power distribution across six lens units rather than a simple retrofocus structure. This allows the back focus length to be reduced while maintaining aberration correction through the coordinated movement and design of multiple lens units with alternating refractive powers.
Solution Approach 2:
Specific conditional expressions are satisfied to optimize the balance between back focus length and aberration control. The focal length ratios between lens units and the back focus distance are precisely controlled to achieve compact dimensions without excessive distortion or lateral chromatic aberration.
3Reliability
If the number of lens units is increased to correct aberrations, then optical performance is improved, but the lens becomes larger and more complex
Solution Approach 1:
The zoom lens uses exactly six lens units with alternating positive and negative refractive powers, providing sufficient degrees of freedom for aberration correction across the zoom range. This segmented structure achieves high optical performance while avoiding excessive complexity through optimized interval control and coordinated movement of the lens units.
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 results in a small-sized, bright zoom lens with satisfactory correction of chromatic aberration, field curvature, and distortion, maintaining high optical performance across the 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; a fourth lens unit having a negative refractive power; a fifth lens unit having a negative refractive power; and a sixth lens unit having a positive refractive power
Data Source
AI summary
Provided is a zoom lens including, in order from an object side to an image side: 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; a fourth lens unit having a negative refractive power; a fifth lens unit having a negative refractive power; and a sixth lens unit having a positive refractive power, wherein an interval between adjacent lens units is changed during zooming, wherein the first lens unit is configured to move toward the object side during zooming from a wide angle end to a telephoto end, and wherein a focal length of the first lens unit, a focal length of the sixth lens unit, and a back focus at the wide angle end are appropriately set.