Zoom Lens Refractive Power Distribution for High Magnification
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Solution Overview
Problem
Conventional zoom lenses have limited zooming rates, resulting in insufficient optical performance, particularly at higher zoom levels due to limitations in refractive power distribution and lens group configurations.
Innovation Solution
A zoom lens configuration comprising multiple lens groups with specific refractive powers and movements, where the first lens group has three or more lenses, the fourth and fifth lens groups have two or less lenses, and the focal lengths and distances between groups are optimized to satisfy conditional expressions, allowing for higher zoom magnification while maintaining good optical performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If conventional zoom lens configurations are used, then the structure is simple and easy to manufacture, but the zooming rate is limited to approximately 50 times and optical performance is insufficient
Solution Approach 1:
The zoom lens is divided into five distinct lens groups (G1-G5) with specific refractive power distributions. The first lens group G1 is further segmented into three or more lenses, while the fourth and fifth lens groups are simplified to two or less lenses each. This segmentation allows for optimized optical performance across different zoom ranges while maintaining manageable structural complexity.
Solution Approach 2:
The patent optimizes specific parameters including the focal lengths of individual lens groups (f1, f2, f3, f4, f5), the distances between lens groups (D1, Dt12), and the refractive powers. By carefully controlling these parameters within specific ranges, the lens achieves high zoom magnification (exceeding 50 times) while maintaining good optical performance across the entire zoom range.
2Manufacturing precision
If the number of lenses in the first lens group is increased to three or more, then the refractive power distribution is optimized for high zoom magnification, but the device complexity increases
Solution Approach 1:
Different regions of the lens system have different numbers of lenses tailored to their specific functions. The first lens group G1, which handles wide-angle imaging, contains three or more lenses to provide sufficient refractive power and correction capabilities. In contrast, the fourth and fifth lens groups, which handle telephoto imaging, are simplified to two or less lenses each, reducing complexity where fewer elements are needed.
Solution Approach 2:
The lens system employs an asymmetric configuration where the number of lenses in each group varies (G1: 3+, G2: 2-3, G3: 2-3, G4: 2-, G5: 2-). This asymmetric arrangement optimizes the refractive power distribution across different zoom ranges, allowing the system to achieve high zoom magnification while maintaining balance in the overall optical design.
3Device complexity
If the fourth and fifth lens groups are simplified to two or less lenses, then the device complexity is reduced, but achieving high zoom magnification becomes more difficult
Solution Approach 1:
The lens groups are designed to move dynamically during zooming operations. The fourth lens group G4 moves to the image surface side upon zooming from wide angle end to telephoto end, and the fifth lens group G5 also moves to the image surface side. This dynamic movement compensates for the reduced number of lenses, allowing the simplified groups to contribute effectively to achieving high zoom magnification.
Solution Approach 2:
The fourth and fifth lens groups, despite having two or less lenses each, are designed to perform multiple functions. They contribute to both the zoom magnification and the correction of optical aberrations. By optimizing their refractive powers (f4 and f5 being negative) and their movement characteristics, these simplified groups achieve universal functionality that supports both high zoom magnification and good optical performance.
4Device complexity
If the fifth lens group moves to the image surface side during zooming, then the zooming mechanism is simplified, but the optical performance at high zoom levels may deteriorate
Solution Approach 1:
The patent controls the movement of the fifth lens group G5 by optimizing its refractive power (f5 < 0) and its movement distance relative to the other lens groups. The conditional expressions constrain the movement characteristics to ensure that even though G5 moves to the image surface side during zooming, the optical performance at the telephoto end remains excellent. This parameter optimization allows the simplified zooming mechanism to maintain high optical quality.
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 proposed configuration achieves high zoom magnification with improved optical performance by optimizing refractive power distribution and lens group movements, effectively addressing the limitations of conventional zoom lenses.
Implementation Method 1
a first lens group having positive refractive power, a second lens group having negative refractive power, a third lens group having positive refractive power, a fourth lens group having negative refractive power, and a fifth lens group having positive refractive power
Data Source
AI summary
A first lens group (G1) having positive refractive power, a second lens group (G2) having negative refractive power, a third lens group (G3) having positive refractive power, a fourth lens group (G4) having negative refractive power, and a fifth lens group (G5) having positive refractive power are arranged in order from an object, and zooming is performed by changing distances between each lens group, and the first lens group (G1) is composed of three or more lenses, the fourth lens group (G4) is composed of two or less lenses, and the fifth lens group (G5) is composed of two or less lenses and moves to an image surface side upon zooming from a wide angle end state to a telephoto end state, and the following conditional expression (1) is satisfied.8.40<f1/(−f2) (1)where, f1 denotes a focal length of the first lens group (G1), andf2 denotes a focal length of the second lens group (G2).