Imaging Lens Grouping for Resolution and Weight Trade-offs
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Solution Overview
Problem
Existing imaging lenses face challenges in achieving high-resolution and wider-angle capabilities while maintaining focusing speed, as increased lens count or size leads to weight and curvature issues.
Innovation Solution
The design includes a first lens group fixed during focusing, a stop, and a second lens group with positive refractive power that moves along the optical axis, along with a third lens group fixed during focusing, with specific refractive power ratios and lens configurations to optimize focal lengths and Abbe numbers, reducing weight and curvature while enhancing resolution and angle.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the number of lenses is increased to achieve higher resolution, then the resolution is improved, but the weight of the lens increases causing slower focusing speed
Solution Approach 1:
The lens system is divided into multiple lens groups with different functions: a first lens group for wide-angle correction, a second lens group for focusing, and a third lens group for image plane correction. This segmentation allows each group to be optimized independently, achieving high resolution without requiring excessive total lens weight.
Solution Approach 2:
Different regions of the lens system are assigned different optical properties. The first lens group uses negative meniscus lenses for wide-angle correction, the second group uses positive power lenses for focusing, and the third group corrects field curvature. This local optimization achieves high resolution across the entire field without uniformly increasing lens weight.
2Measurement precision
If the size of the lens is increased to achieve higher resolution, then the resolution is improved, but the focusing speed decreases due to increased weight
Solution Approach 1:
The focusing function is isolated to the second lens group, which is designed with positive refractive power and positioned near the stop. This segmentation allows the focusing group to be optimized for speed and weight independently from the other lens groups that handle resolution and field curvature correction.
Solution Approach 2:
Instead of making the entire lens system movable for focusing, the patent makes only the second lens group movable while keeping the first and third lens groups fixed relative to the image plane. This inversion of the conventional approach significantly reduces the moving mass while maintaining focusing capability.
3Area of stationary object
If a wider-angle lens is designed, then the angle of view is improved, but field curvature is generated reducing resolution
Solution Approach 1:
The first lens group is specifically designed with negative meniscus lenses having their convex surfaces toward the object side, which is a local optical configuration optimized for wide-angle correction. This local quality assignment allows wide-angle performance without introducing excessive field curvature that would degrade resolution.
Solution Approach 2:
The patent employs specific parameter relationships between lens groups, including the focal length ratios (0.1 < f/f2 < 1.0, -0.2 < f2/f3 < 0.2) and the positioning of the stop relative to the image plane (2BS/(f·tanω) < 2.5). These parameter optimizations enable wide-angle performance while controlling field curvature to maintain resolution.
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 configuration allows for a high-resolution, wider-angle imaging lens that suppresses field curvature and spherical aberration, maintaining focusing speed and reducing the size and weight of the lens system.
Implementation Method 1
a second lens group having a positive refractive power which moves along an optical axis during focusing
Data Source
AI summary
The imaging lens consists of a first lens group fixed to an image plane during focusing, an aperture stop, a second lens group having a positive refractive power which moves along an optical axis during focusing, and a third lens group fixed to the image plane during focusing, in order from an object side. The first lens group includes at least two negative lenses among three lenses from a lens closest to the object side to a third lens, a negative lens of the at least two negative lenses closest to the object side being a negative meniscus lens with its convex surface toward the object side, the second lens group includes at least three lenses, and the third lens group includes at least three lenses.