Macro Lens System with Segmented Movable Groups
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Solution Overview
Problem
Conventional macro lens systems face challenges in miniaturization and weight reduction while maintaining high optical performance, especially at close distances, due to large lens diameters and significant longitudinal chromatic aberrations during 1× magnification imaging.
Innovation Solution
A macro lens system comprising a specific configuration of refractive power groups, including a first lens group with three lenses and independently movable second, fourth, and fifth lens groups, optimized with refractive index and Abbe's number conditions to minimize weight and correct chromatic aberrations, along with aspherical surfaces for improved performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a first lens group with large diameter is moved for focusing operations, then focusing coverage from infinity to close distance is achieved, but weight increases and high speed focusing becomes difficult
Solution Approach 1:
The lens system is divided into multiple lens groups (first through sixth) with different functions. The first lens group with large diameter is kept stationary, while smaller subsequent lens groups are made movable for focusing operations. This segmentation allows the heavy first group to remain fixed while lighter groups perform focusing, resolving the contradiction between focusing coverage and weight.
Solution Approach 2:
Instead of moving the first lens group toward the object side for focusing as in conventional designs, this invention inverts the approach by keeping the first group stationary and moving subsequent groups. This inversion eliminates the need to move the heavy first group while still achieving full focusing coverage from infinity to close distances.
2Measurement precision
If conventional macro lens systems are designed for 1× magnification close distance imaging, then high optical performance is achieved, but longitudinal chromatic aberrations become great
Solution Approach 1:
The patent applies specific parameter constraints to lens materials, including refractive index ranges (1.45 < Nd < 1.90) and Abbe number ranges (20 < vd < 80), to optimize chromatic aberration correction. These parameter changes in material selection enable high optical performance at 1× magnification while controlling longitudinal chromatic aberrations.
Solution Approach 2:
The lens system uses composite material design with multiple lens groups having different refractive indices and Abbe numbers. By combining materials with complementary optical properties (e.g., high dispersion and low dispersion materials), the system achieves superior chromatic aberration correction while maintaining high image quality at close distances.
3Measurement precision
If multiple lens groups are moved for focusing operations to suppress aberration variations, then optical performance is improved, but device complexity increases
Solution Approach 1:
The focusing mechanism is segmented into three independently movable lens groups (second, fourth, and fifth) rather than moving all groups. Each group has specific movement characteristics optimized for different focusing ranges, suppressing aberration variations while reducing overall mechanism complexity compared to moving all lens groups.
Solution Approach 2:
The patent implements dynamic focusing where different lens groups move by different amounts and in different directions based on the focusing distance. The second, fourth, and fifth lens groups have independent movement capabilities that adapt to the focusing requirements, enabling effective aberration correction across the full focusing range from infinity to close distances.
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 enables a compact, lightweight macro lens system that effectively corrects chromatic aberrations and supports high-speed focusing, achieving high image quality even at close distances.
Implementation Method 1
a second lens group G2 having a negative refractive power, a third lens group G3 having a positive refractive power, a fourth lens group G4 having a positive refractive power, a fifth lens group G5 having a positive refractive power, and a sixth lens group G6 having a negative refractive power; and the second lens group G2, the fourth lens group G4, and the fifth lens group G5 are independently moved in a direction of optical axes thereof when focusing from an object at infinity to an object at a most proximate distance
Implementation Method 2
at least one surface within the first lens group to be aspherical. In addition, it is preferable for: at least one surface within the second lens group to be aspherical
Data Source
AI summary
A macro lens system includes, in this order from an object side: a positive first lens group; a negative second lens group; a positive third lens group; a positive fourth lens group; a positive fifth lens group; and a negative sixth lens group. The first lens group is constituted by three lenses. The second lens group, the fourth lens group, and the fifth lens group are independently moved in the direction of the optical axes thereof when focusing from an object at infinity to an object at a most proximate distance.