Moving Imaging Lens Groups for Small F-Number and Compact Optics
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Solution Overview
Problem
There is a demand for an imaging lens that has a small F-number, small size, and maintains favorable optical performance, which existing technologies have not adequately addressed.
Innovation Solution
The imaging lens is composed of a first lens group, a stop, and a second lens group, where the entire lens moves during focusing, with specific conditional expressions governing the focal lengths, refractive powers, and curvature radii of individual lenses to achieve these characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If the F-number is reduced to achieve smaller aperture, then the light gathering capability is improved, but the optical performance deteriorates due to increased aberrations
Solution Approach 1:
The imaging lens is divided into multiple lens groups (first lens group with positive refractive power, second lens group with negative refractive power, third lens group with positive refractive power) that can be independently controlled during focusing. This segmentation allows each group to be optimized for specific aberration correction while working together to achieve small F-number and compact size.
Solution Approach 2:
The patent implements a focusing mechanism where the first lens group, stop, and portion of the second lens group move together during focusing. This dynamic movement allows the system to maintain optimal optical alignment and aberration correction across different focus distances while preserving the small F-number and compact design.
2Volume of moving object
If the lens size is reduced to achieve compact imaging apparatus, then the device portability is improved, but the optical performance deteriorates due to increased aberrations
Solution Approach 1:
The lens system is segmented into multiple groups with specific refractive powers arranged in a compact configuration. The first lens group (positive), second lens group (negative), and third lens group (positive) are positioned to minimize overall lens length while maintaining sufficient separation for aberration correction, achieving both compact size and high optical performance.
Solution Approach 2:
The patent employs conditional expressions that precisely control the focal lengths and refractive powers of individual lenses. By optimizing parameters such as the focal length ratio (f1/f), the refractive power distribution, and curvature radii, the system achieves compact lens size while maintaining favorable optical performance through precise parameter optimization.
3Reliability
If multiple lens groups are added to correct aberrations, then the optical performance is improved, but the device complexity increases
Solution Approach 1:
The imaging lens is divided into three functional groups: first lens group (positive refractive power) for light gathering and initial aberration correction, second lens group (negative refractive power) for field curvature and distortion control, and third lens group (positive refractive power) for final focus and aberration correction. This segmentation provides systematic aberration correction while maintaining manageable structural complexity.
Solution Approach 2:
Each lens group performs multiple functions simultaneously. For example, the first lens group not only gathers light but also contributes to aberration correction and focuses light. The second lens group controls field curvature and distortion while the third lens group completes focus and additional aberration correction. This multi-functionality reduces the need for separate dedicated elements, managing overall complexity.
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 an imaging lens with a small F-number, small size, and excellent optical performance, capable of correcting various aberrations and reducing the overall system size while maintaining high imaging quality.
Implementation Method 1
an imaging lens consisting of, in order from an object side to an image side, a first lens group, a stop, and a second lens group
Data Source
AI summary
An imaging lens consists of, in order from an object side to an image side, a first lens group, a stop, and a second lens group. During focusing, an entire imaging lens moves or the first lens group, the stop, and a portion of the second lens group move. In a case in which a focal length of the imaging lens in a state in which an infinite distance object is in focus is denoted by f, and a focal length of the first lens group is denoted by f1, the imaging lens satisfies Conditional Expression, which is represented by 0.1<f/f1<1.5.