Zoom Lens Aberration Control via Four-Unit Segmentation
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Solution Overview
Problem
Existing zoom lenses face challenges in achieving compactness while maintaining wide-angle performance and correcting distortion and aberrations, particularly in retrofocus configurations with fluctuating aberrations during zooming.
Innovation Solution
A zoom lens configuration comprising a first negative refractive power unit, a second positive refractive power unit, a third negative refractive power unit, and a fourth positive refractive power unit, where the first unit moves during zooming and the fourth unit is fixed or moves from the object side to the image side, satisfying specific conditional expressions to optimize focal length and refractive index ratios for reduced distortion and aberrations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If a retrofocus configuration with a first negative lens unit and second positive lens unit is used to achieve wide-angle performance, then the angle of view is improved, but distortion and aberrations worsen
Solution Approach 1:
The optical system is divided into four lens units with alternating negative and positive refractive powers. The first lens unit (negative) handles the wide-angle field of view, while the second lens unit (positive) corrects the distortion and aberrations generated by the first unit. This segmentation allows each unit to specialize in specific optical functions, resolving the contradiction between wide-angle performance and aberration control.
Solution Approach 2:
The second positive lens unit acts as an intermediary that corrects the optical defects produced by the first negative lens unit. By positioning a positive power unit after the negative power unit, the system mediates the distortion and aberrations, transforming the harmful optical effects into acceptable image quality while maintaining the wide-angle capability.
2Manufacturing precision
If lens units are made thick on the optical axis to correct aberrations, then optical performance is improved, but the overall lens size increases
Solution Approach 1:
The patent employs specific conditional expressions that define optimal ranges for focal lengths, refractive indices, and curvature radii of the lens units. By changing these optical parameters within specified ranges, the system achieves effective aberration correction without requiring excessively thick lens elements, thus controlling the overall lens length while maintaining optical performance.
Solution Approach 2:
The lens units utilize composite optical designs combining multiple lens elements with different refractive powers and materials. The alternating negative and positive power configurations create a composite optical system where the combined effect achieves superior aberration correction compared to individual thick lenses, reducing the overall length requirement.
3Volume of moving object
If a retractable structure is used to reduce lens size, then compactness is improved, but aberration fluctuation during zooming worsens
Solution Approach 1:
The patent designs the zoom lens with dynamic movement characteristics where the first lens unit moves during zooming while the fourth lens unit remains fixed or moves minimally. This dynamic configuration allows the optical system to adapt to different focal lengths while maintaining stable aberration characteristics through the coordinated movement of lens units, resolving the contradiction between compactness and aberration stability.
4Manufacturing precision
If multiple lens units with alternating refractive powers are used to correct distortion, then optical performance is improved, but device complexity increases
Solution Approach 1:
The optical system employs an asymmetric configuration with four lens units having alternating negative and positive refractive powers. This asymmetric arrangement, rather than a symmetric design, efficiently corrects distortion by creating balanced optical paths that cancel out aberrations. The specific sequence of negative-positive-negative-positive units provides effective distortion correction while managing the complexity through a regular alternating pattern.
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 a wide-angle, high-performance, and compact zoom lens with reduced aberration fluctuations and corrected distortion, achieving a balance between wide-angle capability and miniaturization.
Implementation Method 1
a first lens unit having a negative refractive power
Implementation Method 2
a second lens unit having a positive 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 a negative refractive power, a second lens unit having a positive refractive power, a third lens unit having a negative refractive power, and a fourth lens unit having a positive refractive power. The first lens unit includes a negative lens B1Ln with a concave surface facing the object side. The second lens unit includes at least one negative lens. During zooming from a wide-angle end to a telephoto end, the first lens unit moves, and the fourth lens unit is fixed or moves from the object side to the image side. A predetermined condition is satisfied.