Zoom Optical System Aberration Control via Lens Group Segmentation
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Solution Overview
Problem
Conventional zoom optical systems for cameras have insufficient optical performance, particularly in terms of aberration correction during zooming and focusing, which affects image quality and camera performance.
Innovation Solution
A zoom optical system comprising multiple lens groups with specific refractive powers and focal lengths, where the distances between groups change upon zooming and focusing, and the subsequent lens group includes a focusing lens group that moves, satisfying specific conditional expressions to optimize aberration correction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional zoom optical systems are used, then the basic zooming function is achieved, but the optical performance is insufficient due to aberration variations during zooming and focusing
Solution Approach 1:
The zoom optical system is divided into four distinct lens groups (G1, G2, G3, GR) with specific refractive power distributions. Each group has a defined function: G1 and G2 for zooming, G3 for focal length adjustment, and GR for focusing. This segmentation allows independent optimization of each group's movement and aberration correction, resolving the contradiction between optical performance and system complexity.
Solution Approach 2:
The patent specifies precise conditional expressions for focal length ratios (0.18 < -fF/f1 < 0.30 and 0.80 < -f2/f3 < 1.20) and movement distance ratios during focusing (0.30 < |Δd1/Δd2| < 1.50). By controlling these parameters within specific ranges, the system achieves consistent aberration correction across zoom and focus operations, improving optical performance without requiring excessive structural complexity.
2Reliability
If the focusing lens group size is increased to improve aberration correction, then optical performance improves, but the lens barrel size increases
Solution Approach 1:
The patent establishes a specific ratio condition for focusing movement distances (0.30 < |Δd1/Δd2| < 1.50) between the first and second lens groups. This parameter control allows the focusing lens group to achieve effective aberration correction with optimized movement, preventing the need for an oversized lens group that would increase barrel length.
Solution Approach 2:
The focusing lens group GR serves multiple functions: it corrects spherical aberration and coma during focusing, and its movement is coordinated with other lens groups to maintain aberration correction across the entire zoom range. This multi-functionality allows a compact focusing group to achieve comprehensive optical performance.
3Speed
If the focusing lens group movement distance is increased to improve focusing speed, then autofocus speed improves, but aberration variations during zooming increase
Solution Approach 1:
The patent implements coordinated movement control where the focusing lens group's movement distance is dynamically adjusted based on the zoom position. The conditional expression 0.30 < |Δd1/Δd2| < 1.50 ensures that the focusing movement is proportionally adjusted relative to other lens group movements, maintaining aberration consistency while enabling high-speed focusing through optimized movement ranges.
Solution Approach 2:
The system employs dynamic movement ratios between lens groups during focusing operations. Rather than fixed movement distances, the patent specifies ratio ranges that adapt to different zoom positions, allowing the focusing lens group to move optimally fast at each zoom level while maintaining consistent aberration correction throughout the zoom range.
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
The solution effectively suppresses variations in aberrations during zooming and focusing, reducing the size and weight of the focusing lens group, enabling high-speed autofocus and improved optical performance without increasing the lens barrel size.
Implementation Method 1
a first lens group G1 having a positive refractive power; a second lens group G2 having a negative refractive power; a third lens group G3 having a positive refractive power
Data Source
AI summary
A zoom optical system ZL comprises, in order from an object: a first lens group (G1) having a positive refractive power; a second lens group (G2) having a negative refractive power; a third lens group (G3) having a positive refractive power; and a subsequent lens group (GR), wherein upon zooming, distances between the lens groups change, the subsequent lens group (GR) comprises a focusing lens group that moves upon focusing, and conditional expressions 0.18<(−fF)/f1<0.30, and 0.84<(−f2)/f3<1.20, are satisfied, where fF: a focal length of the focusing lens group, f1: a focal length of the first lens group (G1), f2: a focal length of the second lens group (G2), and f3: a focal length of the third lens group (G3).