Compact Wide-Angle Imaging Lens With Stationary First Group
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Solution Overview
Problem
Existing imaging lenses face challenges in achieving a small size while maintaining favorable optical performance, particularly in wide-angle applications.
Innovation Solution
The imaging lens is designed with a configuration that includes a first lens group remaining stationary during focusing, a second lens group moving along the optical axis, and a third lens group, utilizing specific refractive power relationships and lens arrangements to optimize size and optical performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If a conventional wide-angle lens design is used, then the angle of view is wide, but the lens size becomes large
Solution Approach 1:
The lens is divided into three distinct lens groups (first lens group with positive refractive power, second lens group with negative refractive power, third lens group with positive refractive power). This segmentation allows each group to be optimized independently for its specific function while contributing to the overall compact wide-angle design. The first lens group establishes the wide angle of view, the second lens group corrects aberrations, and the third lens group fine-tunes the optical performance, achieving wide-angle capability in a compact form factor.
Solution Approach 2:
Each lens group is assigned specific optical properties and positions to optimize local functions. The first lens group is positioned closest to the object with strong positive refractive power to capture wide angles. The second lens group with negative refractive power is strategically placed to correct spherical and chromatic aberrations. The third lens group with positive refractive power fine-tunes the focal length and corrects residual aberrations. This local optimization of optical qualities enables compact dimensions while maintaining wide-angle performance.
2Area of stationary object
If the lens structure is simplified to reduce size, then the lens becomes compact, but optical performance deteriorates
Solution Approach 1:
The patent specifies precise parameter ranges to optimize the balance between compact size and optical performance. The ratio of focal lengths (0.3 < f1/|f2| < 1.0) controls the relative strength of lens groups, preventing excessive size while maintaining aberration correction. The ratio (0.5 < |f2|/f3 < 2.0) balances the negative and positive refractive powers to correct chromatic and spherical aberrations effectively. These parameter constraints ensure that the compact three-group structure achieves favorable optical performance without requiring complex additional elements.
3Reliability
If more lens elements are added to correct aberrations, then optical performance improves, but the lens size increases
Solution Approach 1:
Each lens group performs multiple functions simultaneously. The first lens group with positive refractive power not only establishes the wide angle of view but also contributes to focusing. The second lens group with negative refractive power corrects spherical aberration, chromatic aberration, and helps in focusing. The third lens group with positive refractive power fine-tunes the focal length, corrects residual aberrations, and assists in focusing. This multi-functionality allows effective aberration correction with minimal elements, keeping the lens compact.
Solution Approach 2:
The second lens group with negative refractive power is designed to move along the optical axis during focusing from infinity to close-range objects. This dynamic positioning allows the lens to maintain focus across different object distances while the compact three-group structure corrects aberrations effectively at all focus positions, eliminating the need for additional static correction elements that would increase size.
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 design achieves a compact wide-angle imaging lens with improved optical performance by reducing the size and weight of the focusing unit, enhancing focusing speed and correcting various aberrations.
Implementation Method 1
a first lens group G1 having a positive refractive power, a second lens group G2 having a negative refractive power, and a third lens group G3 having a positive refractive power
Data Source
AI summary
An imaging lens consisting of, in order from an object side to an image side: a first lens group; a second lens group that has a positive refractive power; and a third lens group that has a negative refractive power, wherein the first lens group includes, successively in order from a position closest to the object side to the image side, two negative lenses and a positive lens, the second lens group includes a positive lens and a negative lens, during focusing from an object at infinity to a closest object, the first lens group remains stationary with respect to an image plane, and the second lens group moves along an optical axis, and assuming that a focal length of the first lens group is f1, and a focal length of the second lens group is f2, Conditional Expression (1) is satisfied: −0.5<f2/f1<0.5 (1).