Zoom Lens Using High Refractive Index Ceramic
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Solution Overview
Problem
Conventional zoom lenses face challenges in achieving a high zoom ratio and compactness while maintaining high optical performance across the entire zoom range, due to limitations in refractive index and Abbe number relationships of materials used, leading to issues with aberration correction and lens thickness.
Innovation Solution
The use of transparent ceramics and oxide monocrystals or polycrystals with unique refractive index and Abbe number characteristics, combined with specific lens unit configurations and movement strategies, to optimize the refractive power and configuration of each lens unit, ensuring a high zoom ratio and compactness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If the refractive power of each lens unit is increased to miniaturize the zoom lens, then the lens thickness increases, but this makes it difficult to correct various aberrations and reduces the effectiveness of miniaturization
Solution Approach 1:
The patent applies parameter changes by selecting lens materials with specific refractive index (nd) and Abbe number (νd) combinations that differ from conventional optical glasses. By changing the material parameters to include ceramics and oxide monocrystals/polycrystals with unique optical properties, the patent achieves both miniaturization and aberration correction without the trade-off that plagues conventional designs.
Solution Approach 2:
The patent employs composite materials strategy by combining multiple lens elements made from different materials (transparent ceramics, oxide monocrystals, oxide polycrystals, and optical glasses) with complementary optical properties. This composite approach allows the system to achieve high refractive power for miniaturization while using materials with appropriate dispersion characteristics to correct chromatic and spherical aberrations.
2Adaptability or versatility
If conventional optical materials are used, then the lens system can be designed, but the refractive index and Abbe number relationships limit the ability to achieve high zoom ratio and compactness simultaneously
Solution Approach 1:
The patent fundamentally changes the material parameter space by introducing transparent ceramics and oxide monocrystals/polycrystals with refractive indices and Abbe numbers that fall outside the conventional glass material envelope. This expansion of material parameters enables the design of compact lens systems with high zoom ratios, as these materials provide higher refractive indices with favorable dispersion characteristics that conventional glasses cannot achieve.
3Length of moving object
If lens elements are made from materials with higher refractive index, then the lens thickness can be reduced, but chromatic aberration increases due to lower Abbe number
Solution Approach 1:
The patent resolves the chromatic aberration issue by using composite materials with complementary properties. High refractive index materials (ceramics, monocrystals) are combined with materials having different dispersion characteristics (optical glasses with higher Abbe numbers). This material composition strategy allows the system to achieve thin lens design while correcting chromatic aberration through the synergistic optical properties of the combined materials.
Solution Approach 2:
The patent applies local quality by assigning different material properties to different lens elements based on their specific functional requirements. Certain lens elements use high refractive index materials for miniaturization, while other elements use materials with appropriate dispersion properties for aberration correction. This localized material optimization allows each lens element to contribute specifically to either compactness or optical quality.
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 approach enables the achievement of a high zoom ratio and high optical performance throughout the zoom range by effectively correcting aberrations and minimizing lens thickness, resulting in a compact and efficient zoom lens system.
Implementation Method 1
The first lens unit includes at least a first lens element made of a material which satisfies the following conditions: 1.65<nd1a≤2.45 and 1.85≤νd1a≤40.0, where nd1a denotes a refractive index for a d-line, and νd1a denotes an Abbe number for the d-line
Data Source
AI summary
A zoom lens achieves a high zoom ratio and high optical performance in an entire zoom range. The 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 unit which includes at least one lens unit. At least the second lens unit is moved during zooming such that a distance between the first and second lens units is larger at a telephoto end than at a wide-angle end. The first lens unit includes at least a first lens element made of a material which satisfies Nd1a>2.3-0.01.nud1a and 1.65a<2.70. The first and second lens units satisfy 2.5<|f1/f2|<12.0.