Medium Telephoto Lens with Cemented Groups for Miniaturization
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Solution Overview
Problem
Conventional medium telephoto lenses face challenges in miniaturization and cost reduction due to complex mechanisms and significant chromatic aberration issues, particularly with the 1-3 lens being a single lens that complicates longitudinal chromatic aberration correction and the combined focal length of the first lens group being long, making it difficult to achieve miniaturization and low cost.
Innovation Solution
A medium telephoto lens configuration with a first lens group consisting of positive lenses with convex surfaces and a negative lens with a concave surface, where the 1-3 and 1-4 lenses are cemented, and the 1-5 and 1-6 lenses are cemented, with only the first lens group moving during focusing, and the second lens group comprising a negative lens with a concave surface and a positive lens with a convex surface, utilizing aspheric surfaces to reduce chromatic aberrations and field curvature.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If both the first lens group and the second lens group are moved while focusing (floating mechanism), then focusing performance is improved, but device complexity and size increase
Solution Approach 1:
The patent extracts the moving function from the second lens group, leaving it fixed while only the first lens group moves during focusing. This simplification reduces mechanism complexity while maintaining focusing performance through the optimized first lens group configuration.
Solution Approach 2:
The patent segments the lens system into two distinct groups with different functional roles: the first lens group (1-1 to 1-7) performs focusing by moving along the optical axis, while the second lens group (2-1 to 2-3) remains fixed and provides optical correction. This functional segmentation simplifies the overall mechanism.
2Reliability
If the combined focal length of the first lens group is made long, then chromatic aberration correction is improved, but lens size increases
Solution Approach 1:
The patent uses composite lens structures with specific glass combinations (e.g., cemented lenses of 1-3 and 1-4, and 1-5 and 1-6) with different refractive indices and Abbe numbers. This allows achieving the required chromatic aberration correction with shorter focal lengths by optimizing the optical properties of each lens element.
Solution Approach 2:
The patent optimizes parameters such as the focal lengths of individual lenses (f11 to f17), the distances between lens elements, and the curvature radii to achieve the desired chromatic aberration correction without requiring a long combined focal length for the first lens group.
3Device complexity
If a single lens is used for the 1-3 position, then device complexity is reduced, but chromatic aberration correction becomes difficult
Solution Approach 1:
The patent segments the first lens group into multiple elements (1-1 to 1-7) with specific functions: positive lenses (1-1, 1-2, 1-3, 1-6, 1-7) for focusing and negative lenses (1-4, 1-5) for chromatic aberration correction. This segmentation enables effective chromatic aberration correction while maintaining manageable complexity.
Solution Approach 2:
The patent employs cemented lens combinations (1-3 with 1-4, and 1-5 with 1-6) using glass materials with different Abbe numbers to correct chromatic aberration. The cemented structure integrates multiple lens elements while maintaining compact form factor.
4Manufacturing precision
If the difference in Abbe numbers between cemented lenses is small, then manufacturing precision is improved, but chromatic aberration correction becomes difficult
Solution Approach 1:
The patent selects glass materials with specific Abbe number differences for the cemented lenses (1-3/1-4 and 1-5/1-6) to optimize chromatic aberration correction. The patent specifies that the difference in Abbe numbers between cemented lenses should be within certain ranges to balance correction effectiveness with manufacturing feasibility.
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 simplifies the focus mechanism, achieves miniaturization, and effectively corrects chromatic aberrations, enabling high-resolution imaging with reduced size and cost, while maintaining performance across varying magnifications from infinity to short distances.
Implementation Method 1
the 1-3 lens and the 1-4 lens are cemented to each other and the 1-5 lens and the 1-6 lens are cemented to each other... effectively corrects chromatic aberrations
Implementation Method 2
utilizing aspheric surfaces to reduce chromatic aberrations and field curvature
Implementation Method 3
only the first lens group moves in the optical axis direction while focusing
Data Source
AI summary
A first lens group having positive refractive power and a second lens group are arranged in this order from an object side, and only the first lens group moves in the optical axis direction while focusing. The first lens group substantially consists of a positive 1-1 lens, a positive 1-2 lens, a positive 1-3 lens, a negative 1-4 lens, an aperture stop, a negative 1-5 lens, a positive 1-6 lens, and a positive 1-7 lens. The 1-3 lens and the 1-4 lens are cemented to each other, and the 1-5 lens and the 1-6 lens are cemented to each other. The second lens group substantially consists of a negative 2-1 lens and a positive 2-2 lens. Only the first lens group moves in the optical axis direction while focusing.