Wide-angle Zoom Lens System Aberration Control
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Solution Overview
Problem
Conventional wide-angle zoom lens systems for digital SLR cameras with smaller imaging devices struggle to achieve a wide angle-of-view of more than 100 degrees and a zoom ratio greater than 2, often compromising on either angle-of-view or zoom ratio.
Innovation Solution
A wide-angle zoom lens system comprising a negative first lens group, a positive second lens group, a negative third lens group, and a positive fourth lens group, with specific focal length ratios and lens configurations that adjust during zooming to achieve an angle-of-view of approximately 100 degrees and a zoom ratio of 2.5 to 3.0, while correcting aberrations such as spherical aberration, coma, and distortion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If a conventional wide-angle zoom lens system is designed for digital SLR cameras with smaller imaging devices, then the angle-of-view can be increased, but the zoom ratio is limited to approximately 2 or less
Solution Approach 1:
The zoom lens system is divided into four distinct lens groups (negative first lens group, positive second lens group, negative third lens group, and positive fourth lens group) that can move independently relative to each other during zooming. This segmentation allows complex optical path control to achieve both wide angle-of-view and high zoom ratio simultaneously, resolving the contradiction between these two parameters.
Solution Approach 2:
The lens groups are designed with dynamic movement capabilities where the distances between lens groups change during zooming operation. Specifically, the distance between the negative first and positive second lens groups decreases, while the distance between positive second and negative third lens groups increases, enabling the system to dynamically adjust focal length from wide-angle to telephoto while maintaining aberration correction.
2Adaptability or versatility
If the zoom ratio is increased to more than 2, then the versatility is improved, but the angle-of-view cannot exceed 100 degrees
Solution Approach 1:
The system achieves both high zoom ratio and wide angle-of-view by precisely controlling the focal lengths of individual lens groups and their relative positions. The focal length ratios are constrained by specific mathematical relationships (|f1/fw| between 1.1-2.0, f4/fw between 2.0-3.5) to optimize the balance between zoom capability and wide-angle performance, allowing the system to achieve zoom ratios of 2.5-3.0 while maintaining 100-degree or greater angle-of-view.
3Adaptability or versatility
If a four-lens-group arrangement is used to increase zoom ratio, then the versatility is improved, but the device complexity increases
Solution Approach 1:
The zoom lens system is divided into four distinct lens groups (negative first lens group, positive second lens group, negative third lens group, and positive fourth lens group) that can move independently relative to each other during zooming. This segmentation allows complex optical path control to achieve both wide angle-of-view and high zoom ratio simultaneously, resolving the contradiction between these two parameters.
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 system effectively provides a wide angle-of-view of approximately 100 degrees and a zoom ratio of 2.5 to 3.0, while adequately correcting aberrations, making it suitable for digital SLR cameras with smaller imaging devices.
Implementation Method 1
a wide-angle zoom lens system including a negative first lens group, a positive second lens group, a negative third lens group and a positive fourth lens group
Data Source
AI summary
A wide-angle zoom lens system includes a negative first lens group, a positive second lens group, a negative third lens group and a positive fourth lens group, in this order from the object. Upon zooming from the short focal length extremity to the long focal length extremity, a distance between the negative first lens group and the positive second lens group decreases, a distance between the positive second lens group and the negative third lens group increases, and a distance between the negative third lens group and the positive fourth lens group decreases. The wide-angle zoom lens system satisfies the following conditions:1.1<|f1|/fw<2.0(f1<0) (1)2.0<f4/fw<3.5 (2)2.5<fBw/fw<3.5 (3)