Imaging Lens Aberration Control via Movable Group Dynamics
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional imaging lens systems face challenges in maintaining optimal aberration correction and focal length adjustments when switching between infinity and close-range focusing, particularly in achieving a back focal length sufficient for single-lens reflex cameras with an F-value of approximately 1.4 and an angle of view of 45 degrees.
Innovation Solution
The proposed imaging lens system consists of a first group with positive power and a second group with positive power, where the second group is movable relative to the first group to adjust the focal length ratio, satisfying specific conditional expressions to optimize power distribution and curvature, thereby preventing excessive aberrations and maintaining performance across focus ranges.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of stationary object
If a modified-double Gauss configuration with symmetrical lens arrangement is used to achieve F-value of 1.4 and 45-degree angle of view, then the back focal length is sufficient for single-lens reflex camera, but the aberration correction deteriorates when switching between infinity and close-range focusing
Solution Approach 1:
The patent applies the dynamics principle by making the second lens group movable relative to the first lens group. The second group moves along the optical axis to change the distance between the two groups during focusing from infinity to close range. This dynamic adjustment allows the lens system to maintain optimal aberration correction at different focus distances while preserving the sufficient back focal length required for single-lens reflex cameras.
2Length of stationary object
If a front convertor with negative lens group is added to obtain long back focus while improving depiction performance, then the back focal length increases, but the device complexity increases
Solution Approach 1:
The patent applies segmentation by dividing the lens system into two distinct groups: a first lens group with positive power and a second lens group with positive power. The first group includes sub-groups with specific positive and negative lens components, while the second group contains a stop and additional lens elements. This segmented structure achieves the required back focal length and aberration correction without requiring a complex front convertor configuration.
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 effectively reduces fluctuations in aberrations and maintains high performance by adjusting the power ratio and curvature of lens surfaces, ensuring well-corrected spherical aberration, chromatic aberration, and distortion across both infinity and close-range focusing.
Implementation Method 1
an imaging lens system includes a first group having positive power; and a second group having positive power... the first group includes a first sub-group and a second sub-group... the first sub-group includes a lens closest to the object side at one end of the first sub-group and a negative lens component closest to the object side at another end of the first sub-group
Data Source
AI summary
An imaging lens system includes a first group having positive power and a second group having positive power disposed in that order from an object side to an image. The first group includes a first sub-group and a second sub-group. The second group includes a third sub-group, a stop, and a fourth sub-group. Conditional expressions (1), (2), and (3) below are satisfied:0.07<f2/f1<0.4 (1);0.45<f2/f2a<0.7 (2);and1.05<f/R1aN<1.55 (3)wheref denotes a focal length of an entirety of the imaging lens system focused at infinity,f1 denotes a focal length of the first group,f2 denotes a focal length of the second group focused at infinity,f2a denotes a focal length of the third sub-group focused at infinity, andR1aN denotes a radius of curvature of a surface closest to the image side within the first sub-group.