Fixed-Focal-Length Optical System with Multi-Unit Aberration Correction
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Solution Overview
Problem
Existing optical systems with a large aperture ratio struggle to effectively correct various aberrations such as lateral chromatic aberration, longitudinal chromatic aberration, spherical aberration, coma, and astigmatism, particularly due to the use of materials with high refractive indices in the second lens unit.
Innovation Solution
An optical system design featuring a front lens unit with positive or negative refractive power, a rear lens unit with negative refractive power comprising two or more positive lenses, and a middle unit with positive refractive power, where the distances between adjacent lens units change during focusing, adhering to specific refractive power and Abbe number conditions to correct aberrations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If a material having a high refractive index is used for the second lens unit to achieve a large aperture ratio, then the aperture ratio is improved, but the lateral chromatic aberration cannot be corrected
Solution Approach 1:
The patent changes the material parameter (Abbe number) of the second lens unit from high to low, and adjusts the refractive power distribution among lens units. By setting the second lens unit with low Abbe number and assigning it negative refractive power, the system achieves both large aperture ratio and effective correction of lateral chromatic aberration.
Solution Approach 2:
The patent uses composite lens unit design with different glass materials having specific Abbe number relationships. The second lens unit employs a low Abbe number material while other units use materials with higher Abbe numbers, creating a composite optical system that corrects chromatic aberrations across the spectrum while maintaining large aperture.
2Illumination intensity
If the optical system is designed with a large aperture ratio, then the light gathering ability is improved, but various aberrations such as longitudinal chromatic aberration, spherical aberration, coma, and astigmatism significantly affect image quality
Solution Approach 1:
The patent divides the optical system into multiple lens units (first, second, third lens units) with distinct functions. The second lens unit specifically addresses chromatic aberrations, while other units handle spherical aberration, coma, and astigmatism, allowing each segment to optimize for its specific aberration type while maintaining large aperture.
Solution Approach 2:
The patent assigns different optical properties to different lens units: the second lens unit has low Abbe number for chromatic aberration correction, while other units have higher Abbe numbers. This local differentiation of material properties enables targeted correction of various aberrations throughout the optical path.
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 system achieves satisfactory correction of various aberrations while maintaining a wide angle and large aperture ratio, ensuring high image quality and compactness.
Implementation Method 1
an optical system having a large aperture ratio that includes, in order from an object side to an image side, a first lens unit having a positive or negative refractive power, a second lens unit having a positive refractive power, and a third lens unit having a negative refractive power
Data Source
AI summary
An optical system with a fixed focal length includes a front lens unit closest to an object, a rear lens unit having a negative refractive power closest to an image plane, and a middle unit having a positive refractive power as a whole, including one or more lens units, and disposed between the front lens unit and the rear lens unit. A distance between adjacent lens units changes during focusing. The rear lens unit includes two or more positive lenses. A predetermined condition is satisfied.