Zoom Lens Aberration Control via Cemented Lens Segmentation
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Solution Overview
Problem
Existing large-aperture zoom lenses face challenges in achieving a wide angle of view while maintaining good optical performance and controlling aberrations, particularly spherical and chromatic aberrations, especially when the angle of view exceeds 80 degrees, and they tend to be large and heavy or difficult to miniaturize.
Innovation Solution
A zoom lens configuration with a first positive refractive power lens unit, a second negative refractive power lens unit, and a rear lens group with a positive refractive power, where the second lens unit includes a negative lens component and a cemented lens with specific refractive index ratios, and the lens units move relative to each other during zooming to maintain optical performance and correct aberrations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If a lens unit having a negative refractive power is provided nearest to the object-side end, then the aperture can be enlarged, but the lens system becomes large and heavy
Solution Approach 1:
The second lens unit is divided into multiple lens components including a negative lens component and a cemented lens with a positive lens component and a negative lens component. This segmentation allows for optimized optical performance while controlling the overall size and weight of the lens system.
Solution Approach 2:
The cemented lens in the second lens unit uses lens components with specific refractive indices satisfying 1.3 < (Ndp - Ndn) < 2.0, where Ndp is the refractive index of the positive lens component and Ndn is the refractive index of the negative lens component. This local optimization of material properties enables effective aberration correction while maintaining compact dimensions.
2Weight of stationary object
If a lens unit having a positive refractive power is provided nearest to the object-side end, then the lens system size is reduced, but the angle of view cannot be increased sufficiently
Solution Approach 1:
The second lens unit is segmented into multiple lens components including a negative lens component and a cemented lens. This segmentation enables the lens system to achieve a wider angle of view while maintaining a compact overall size.
Solution Approach 2:
The invention optimizes the refractive index difference parameter (Ndp - Ndn) within the range of 1.3 to 2.0 for the cemented lens components. This parameter optimization enables the lens system to achieve a wider angle of view while maintaining compact dimensions.
3Adaptability or versatility
If the angle of view is increased to exceed 80 degrees, then the versatility is improved, but spherical aberration and chromatic aberration cannot be corrected effectively
Solution Approach 1:
The cemented lens in the second lens unit uses lens components with specifically controlled refractive indices satisfying 1.3 < (Ndp - Ndn) < 2.0. This local optimization of material properties enables effective correction of spherical and chromatic aberrations while maintaining a wide angle of view.
Solution Approach 2:
The cemented lens combines a positive lens component and a negative lens component with different refractive indices. This composite structure enables simultaneous correction of multiple types of aberrations including spherical and chromatic aberrations while maintaining a wide angle of view.
4Weight of stationary object
If the lens system is miniaturized, then the portability is improved, but the back focal length becomes insufficient
Solution Approach 1:
The second lens unit is divided into multiple lens components including a negative lens component and a cemented lens. This segmentation allows for optimized optical path management, enabling sufficient back focal length while maintaining compact overall dimensions.
Solution Approach 2:
The invention optimizes the refractive index difference parameter (Ndp - Ndn) within the range of 1.3 to 2.0, which enables compact lens design while maintaining sufficient back focal length for the desired angle of view.
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 zoom lens with a large aperture and wide angle of view, effectively reducing variations in aberrations across all zooming positions, facilitating size reduction while maintaining high optical performance.
Implementation Method 1
a cemented lens with specific refractive index ratios, where Ndp denotes a refractive index of the positive lens component of the cemented lens, and Ndn denotes a refractive index of the negative lens component of the cemented lens
Data Source
AI summary
A zoom lens includes, in order from an object side to an image side, a first lens unit having a positive refractive power, a second lens unit having a negative refractive power, and a rear lens group including lens units and as a whole having a positive refractive power. Distances between the lens units change during zooming. The second lens unit includes, in order from the object side to the image side, a negative lens component and a cemented lens including a negative lens component and a positive lens component. The second lens unit includes at least five lens components. A focal length f1 of the first lens unit, a focal length f2 of the second lens unit, a refractive index Ndp of the positive lens component of the cemented lens, and a refractive index Ndn of the negative lens component of the cemented lens are set appropriately.