Compact Zoom Lens with Five-Group Configuration for Wide Angle View
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Solution Overview
Problem
Conventional zoom lenses for digital cameras are not compact enough and do not provide a wide enough angle of view, with some designs being excessively large due to back focus requirements and others lacking sufficient aberration correction.
Innovation Solution
A zoom lens configuration comprising a first lens group with negative refractive power, a stop, a second lens group with positive refractive power, a third lens group with negative refractive power, a fourth lens group with positive refractive power, and a fifth lens group with positive refractive power, where the first four groups move along the optical axis to adjust distances and the fifth group is fixed, optimizing focal lengths and surface shapes to achieve a compact design with a wide angle of view and corrected aberrations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a large amount of back focus is secured, then the lens can be designed with simpler structure, but the total length becomes excessively long
Solution Approach 1:
The lens is divided into five distinct lens groups (G1-G5) with different refractive powers, allowing each group to be optimized independently. This segmentation enables compact overall design while maintaining necessary back focus distance through precise positioning of each group
Solution Approach 2:
The lens groups are arranged in a nested configuration where G1 (negative) and G2 (positive) form a compact unit, and G3 (negative) and G4 (positive) form another unit, with G5 fixed at the image plane. This nesting allows efficient space utilization and reduced total length
2Adaptability or versatility
If the lens system is proportionally enlarged to correspond to APS-C type image sensor, then the image sensor compatibility is improved, but the lens system becomes excessively large
Solution Approach 1:
The focal lengths of individual lens groups are specifically optimized (|f1|>f2, f3<|f4|, f5>0) to achieve the desired field of view and image size for APS-C sensors without requiring proportional enlargement of the entire lens system, thereby maintaining compact dimensions
3Adaptability or versatility
If the full angle of view is increased to approximately 100 degrees, then the wide angle capability is improved, but the aberration correction becomes insufficient
Solution Approach 1:
Each lens group is assigned a specific refractive power sign and focal length relationship to address particular aberrations: G1 (negative) controls field curvature, G2 (positive) corrects spherical aberration, G3 (negative) and G4 (positive) work together to correct chromatic aberrations, and G5 (positive) fine-tunes the image quality, achieving comprehensive aberration correction across the wide 110-degree field of view
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 results in a compact zoom lens with a short total length, achieving a wide angle of view of approximately 110 degrees and satisfactory correction of various aberrations, enabling miniaturization and high-quality imaging.
Implementation Method 1
a first lens group G1 having a negative refractive power, a stop St, a second lens group G2 having a positive refractive power, a third lens group G3 having a negative refractive power, a fourth lens group G4 having a positive refractive power
Implementation Method 2
the first lens group through the fourth lens group move along the optical axis while changing magnification from the wide angle end to the telephoto end so as to change the distances among one another
Data Source
AI summary
A zoom lens consists of a negative first lens group, a stop, a positive second lens group, a negative third lens group, a positive fourth lens group, and a positive fifth lens group in this order from the object side. The first lens group through the fourth lens group move along the optical axis while changing magnification such that the distance between the first lens group and the second lens group is reduced and the distance between the second lens group and the third lens group is increased. The fifth lens group is fixed with respect to an image surface while changing magnification. The first lens group consists of a first lens, a second lens, a third lens, and a fourth lens in this order from the object side.