Zoom Lens Abbe Number Optimization for Wide-Angle Brightness
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Solution Overview
Problem
Current zoom lenses for image pickup devices face challenges in achieving a wide angle of view, small size, high optical quality, and reduced out-of-focus issues across a wide wavelength range, including near-infrared light, while maintaining a compact and bright design.
Innovation Solution
A zoom lens configuration featuring a first lens unit with negative refractive power and a second lens unit with positive refractive power, where the second lens unit includes positive lenses that satisfy specific conditional expressions regarding Abbe numbers and partial dispersion ratios, optimizing lens materials to correct chromatic aberration and spherical aberration across the visible and near-infrared spectrum.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If a zoom lens is designed with a wide angle of view and small F-number, then the brightness and field of view are improved, but the degree of out-of-focus increases and optical characteristics deteriorate
Solution Approach 1:
The patent applies local quality by using different glass materials with specific refractive indexes and Abbe numbers in different lens units. The first lens unit uses materials with specific dispersion properties to correct chromatic aberration, while the second lens unit uses materials optimized for spherical aberration correction, allowing each part to have specialized optical properties that collectively improve overall image quality while maintaining wide angle and bright characteristics
Solution Approach 2:
The patent employs composite materials by combining multiple glass types with different optical properties in a single lens system. Specifically, it uses glass materials with refractive indexes ranging from 1.8 to 2.1 and Abbe numbers between 20-40 in the first lens unit, and glass materials with refractive indexes from 1.5 to 1.8 and Abbe numbers from 30-50 in the second lens unit, creating a composite optical system that balances brightness with optical quality
2Reliability
If the lens configuration is optimized for high optical characteristics, then image quality is improved, but the lens size and complexity increase
Solution Approach 1:
The patent divides the lens system into two functional segments: a first lens unit with positive refractive power that handles chromatic aberration correction using high dispersion glass materials, and a second lens unit with negative refractive power that manages spherical aberration using low dispersion glass materials. This segmentation allows each unit to be optimized independently for its specific function, achieving high optical quality without excessive overall complexity
Solution Approach 2:
The patent achieves optimized optical characteristics by carefully controlling key parameters: the refractive indexes (1.8-2.1 for first unit, 1.5-1.8 for second unit), Abbe numbers (20-40 for first unit, 30-50 for second unit), and the ratio of focal lengths between the two units (0.3-0.7). These parameter constraints enable high image quality while limiting the number of design variables and simplifying the manufacturing process
3Ease of operation
If the lens units are moved along different loci during zooming, then zooming performance is improved, but the mechanical complexity and size increase
Solution Approach 1:
The patent implements dynamic zooming by allowing the first and second lens units to move along different loci during focal length changes. The first lens unit moves along a locus that optimizes chromatic aberration correction, while the second lens unit moves along a separate locus that maintains spherical aberration correction. This dynamic, differentiated movement enables smooth zooming performance across the focal range while keeping the mechanical structure relatively simple through coordinated control of the two units
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 achieves high optical performance over the entire zoom range with a small size, reduced out-of-focus issues, and a wide angle of view, supporting image pickup elements with high pixel density, such as full HD or more, while maintaining a compact and bright design.
Implementation Method 1
the second lens unit includes a positive lens PL satisfying conditional expressions (1) to (3), where nC, nt and nF are refractive indexes of a lens material for a C-line, a t-line and an F-line, respectively, and νd is an Abbe number for a d-line
Data Source
AI summary
A zoom lens is provided which has a wide angle of view and is bright and in which the entire lens system is compact and which can achieve high optical characteristic over the entire zoom range.