Zoom Lens Aberration Control via Movable Unit Loci
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Solution Overview
Problem
Conventional four-unit zoom lenses face challenges in achieving a wide angle of view, high zoom ratio, and size and weight reduction while maintaining effective aberration correction, particularly in the focal length range from the wide-angle end to the zoom middle position, due to increased variation in aberrations and performance degradation.
Innovation Solution
A zoom lens configuration with three or more movable units, including a first lens unit with positive refractive power that does not move, a second and third lens unit with negative refractive power that move during zooming, and a relay lens unit with positive refractive power that does not move, where the second lens unit moves towards the image side from the wide-angle end to the telephoto end, optimizing the moving loci and power arrangement to satisfy specific conditional expressions for improved performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the refractive power of each unit is increased to achieve a wider angle of view, a higher zoom ratio, and further size and weight reduction, then the angle of view and zoom ratio are improved, but variation in aberrations increases and performance degradation occurs in the periphery of the field
Solution Approach 1:
The patent applies parameter changes by precisely controlling the refractive power distribution among lens units and defining specific movement ranges for each unit during zooming. The conditional expressions (1) and (2) establish optimal parameter ranges that maintain aberration correction while achieving wide angle of view and high zoom ratio. The second and third lens units move along specifically designed loci with controlled distances to the optical axis, transforming the parameter relationships to resolve the contradiction between zoom performance and aberration control.
2Productivity
If three or four zooming units move along different loci during zooming, then the zoom ratio and angle of view are improved, but aberration correction is not effective in the focal length range from the wide-angle end to the zoom middle position
Solution Approach 1:
The patent applies local quality by designing different movement loci for different lens units based on their specific positions and functions in the optical system. The second lens unit moves along a locus where its distance to the optical axis is controlled to be 0.05 times the focal length at a specific zoom position, while the third lens unit follows a different locus. This localized optimization of movement paths ensures that each unit contributes effectively to aberration correction in its specific operational range, particularly in the focal length range from wide-angle end to zoom middle position.
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 achieves favorable optical performance, a wide angle of view, high power, and size and weight reduction by effectively correcting field curvature and reducing aberrations across the zoom range, while maintaining a compact and lightweight design.
Implementation Method 1
a first lens unit having a positive refractive power that does not move for zooming, a second lens unit having a negative refractive power that moves during zooming, a third lens unit having a negative refractive power that moves during zooming, and a fourth lens unit having a negative refractive power that moves during zooming
Data Source
AI summary
A zoom lens includes, in order from the object side, a first lens unit having a positive refractive power that does not move for zooming, second to fourth lens units each having a negative refractive power that moves for zooming, and a relay lens unit having a positive refractive power and being closest to the image side that does not move for zooming. The second lens unit moves to the image side from the wide-angle end to the telephoto end. When a focal length fx determined by a focal length fw of the zoom lens at the wide-angle end and a zoom ratio Z is fx=fw×Z0.38, the zoom lens satisfies 0.05<L2 min/L2w<0.98, where L2 min is a minimum distance between the second and third lens units in a zoom range from the wide-angle end to the focal length fx, and L2w is a distance between them at the wide-angle end.