Zoom Lens Aberration Correction via Cemented Positive Unit
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Solution Overview
Problem
Existing zoom lenses face challenges in achieving high optical performance while maintaining a small size, particularly in reducing chromatic aberration and spherical aberration across the entire zoom range, especially when a high zoom ratio and large image sensor are required.
Innovation Solution
A zoom lens configuration with specific refractive power and curvature radius inequalities, including a first positive lens unit, a negative second lens unit, and a positive third lens unit, along with a cemented lens structure, is used to optimize the focal lengths and refractive indices of lens units, ensuring proper aberration correction and robustness against manufacturing errors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If glass materials having large refractive indexes are heavily used to shorten overall lens length, then lens size is reduced, but chromatic aberration increases and manufacturing robustness decreases
Solution Approach 1:
The patent applies parameter changes by carefully selecting and optimizing the refractive indexes (nd1=1.501, nd2=1.647, nd3=1.751) and Abbe numbers (vd1=64.2, vd2=24.0, vd3=18.8) of the lens materials. This allows achieving compact lens size while controlling chromatic aberration through precise material parameter selection rather than simply using high refractive index materials.
Solution Approach 2:
The patent uses composite material principles by combining multiple lens materials with different optical properties (different refractive indexes and Abbe numbers) in a specific configuration. The first, second, and third lens units use different glass materials to balance chromatic aberration correction with compact size, avoiding reliance on single high-index materials.
2Volume of moving object
If aspherical lenses and increased refractive power are used to shorten overall lens length, then lens size is reduced, but on-axis chromatic aberration reduction becomes difficult across the entire zoom range
Solution Approach 1:
The patent uses parameter changes by optimizing the refractive power distribution across the zoom range (focal length 15.45mm to 67.94mm) and adjusting the material parameters of each lens unit to maintain chromatic aberration control throughout the entire zoom range, not just at fixed focal lengths.
Solution Approach 2:
The patent applies dynamics by designing the lens system to adapt its chromatic aberration correction across the zoom range. The lens units move relative to each other during zooming, and the optical design maintains aberration control dynamically throughout the focal length range rather than statically at one position.
3Adaptability or versatility
If high zoom ratio and focal length on telephoto side are ensured, then zoom capability is improved, but various aberrations especially lateral chromatic aberration increase on wide-angle side
Solution Approach 1:
The patent applies parameter changes by optimizing the focal length range (achieving zoom ratio of 4.4x from 15.45mm to 67.94mm) while adjusting the material parameters and optical configuration to control lateral chromatic aberration across the entire zoom range, particularly at the wide-angle end.
Solution Approach 2:
The patent uses local quality principles by addressing aberration control specifically at different parts of the zoom range. The optical design pays special attention to controlling lateral chromatic aberration at the wide-angle end while maintaining telephoto performance, applying different correction strategies for different focal length regions.
4Manufacturing precision
If the number of lens units is increased to improve optical performance, then aberration correction is improved, but lens system size and complexity increase
Solution Approach 1:
The patent applies parameter changes by optimizing the refractive indexes and Abbe numbers of the three lens units to achieve good aberration correction with a limited number of elements. The specific material parameters (nd1=1.501, vd1=64.2; nd2=1.647, vd2=24.0; nd3=1.751, vd3=18.8) enable effective chromatic and spherical aberration control without requiring many lens units.
Solution Approach 2:
The patent uses merging principles by combining multiple functions into fewer lens units. Each lens unit is designed to handle multiple aberration correction tasks simultaneously, reducing the total number of required elements while maintaining optical performance.
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 wide-angle zoom lens with high optical performance and reduced size, effectively correcting chromatic and spherical aberrations across the zoom range while being robust against manufacturing errors and decentration.
Implementation Method 1
a first cemented lens having a negative refractive power and a second cemented lens having a positive refractive power. The first cemented lens consists of, in order from the object side to the image side, a first lens having a biconvex shape and having a positive refractive power and a second lens having a negative refractive power
Implementation Method 2
a first lens unit having a positive refractive power, a second lens unit having a negative refractive power, a third lens unit having a positive refractive power, and a rear unit including one or more lens units
Data Source
AI summary
A zoom lens consists of, from an object side, positive, negative, and positive first to third lens units and a rear unit including one or more lens units. Each distance between adjacent lens units changes during zooming. During zooming from wide-angle to telephoto ends, the first lens unit moves, a distance between the first and second lens units widens, and a distance between the second and third lens units narrows. A positive unit is the third lens unit or is, if an image-side lens unit next to the third lens unit is a positive lens unit, a lens unit of the third and positive lens units. The positive unit includes, from the object side, negative and positive first and second cemented lenses. The first cemented lens consists of, from the object side, a biconvex-shaped positive first lens and a negative second lens. Predetermined conditions are satisfied.