Optical System Aberration Correction via Lens Unit Segmentation
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Solution Overview
Problem
Image pickup optical systems face challenges in achieving a wide field angle and large aperture ratio while effectively correcting high-order aberrations such as sagittal coma flare, which are exacerbated by the asymmetric refractive power arrangement with respect to the aperture stop.
Innovation Solution
The optical system comprises a first lens unit with positive refractive power and a second lens unit that moves during focusing, featuring a front unit, an aperture stop, and a rear unit with positive refractive power, where the first lens unit includes a negative lens closest to the object side and multiple positive lenses on the image side, with specific distance ratios and refractive power arrangements to correct aberrations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If refractive power arrangement is made asymmetric with respect to aperture stop to achieve wide field angle and large aperture ratio, then optical performance is improved, but high-order aberrations including sagittal coma flare are generated
Solution Approach 1:
The optical system is divided into multiple lens units with specific refractive power distributions. The first lens unit has negative refractive power while the second lens unit has positive refractive power, creating a segmented refractive power arrangement that balances aberration correction with wide field angle and large aperture ratio performance.
Solution Approach 2:
Different regions of the optical system are assigned different refractive properties. The aperture stop is positioned in the second lens unit with positive refractive power, creating a local quality difference that helps control the sagittal coma flare while maintaining the asymmetric refractive power arrangement for wide field angle.
2Adaptability or versatility
If asymmetric refractive power arrangement is used to achieve large aperture ratio, then optical characteristic is improved, but various aberrations are generated
Solution Approach 1:
The first lens unit with negative refractive power acts as an intermediary element between the object side and the aperture stop. This intermediary lens unit helps correct aberrations generated by the asymmetric refractive power arrangement while maintaining the large aperture ratio capability.
3Object-generated harmful factors
If complex lens structure is used to correct aberrations, then optical performance is improved, but device complexity increases
Solution Approach 1:
Multiple lens units are merged into a coordinated system where the first lens unit (negative refractive power) and second lens unit (positive refractive power) work together. This merging approach achieves effective aberration correction including sagittal coma flare while keeping the overall lens structure manageable and not excessively complex.
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 allows for a high-performance optical system with a wide field angle and large aperture ratio, effectively correcting spherical aberration and sagittal coma flare, while reducing the load on the focus driving mechanism and maintaining a sufficiently long back focus.
Implementation Method 1
a first lens unit having a positive refractive power; and a second lens unit having a positive refractive power... the first lens unit including a negative lens that has a convex surface facing the object side
Data Source
AI summary
An optical system includes, in order from object side: a positive first lens unit; and a positive second lens unit moving during focusing. The second lens unit includes, in order from object side, a front unit, an aperture stop, and a positive rear unit. The first unit includes a negative lens that has a convex surface facing object side and is arranged closest to object side, and three or more positive lenses on image side of the negative lens. A distance, on optical axis, from a lens surface on object side of a second positive lens counted from image side of the three or more positive lenses to a lens surface closest to image side of the first unit, and a distance, on optical axis, between a lens surface closest to object side and that closest to image side of the first unit are each appropriately set.