Zoom Lens Abbe Constant Optimization
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Solution Overview
Problem
Conventional zoom lens systems face difficulties in adequately correcting longitudinal chromatic aberration, especially at the telephoto end with high magnification ratios, which affects image quality and is challenging to achieve in a compact and lightweight design.
Innovation Solution
A zoom lens system comprising specific refractive power and Abbe constant conditions for its lens units, including a first lens unit with positive refractive power that does not move, a second lens unit with negative refractive power that moves, a third lens unit with variable refractive power for magnification-varying, and a fourth lens unit with positive refractive power that does not move, to optimize the correction of secondary spectrum longitudinal chromatic aberration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional zoom lens systems are used with high magnification ratios, then the telephoto end focal length increases, but longitudinal chromatic aberration becomes difficult to correct sufficiently
Solution Approach 1:
The patent applies parameter changes by precisely controlling the Abbe constants (ν1, ν2, ν3, ν4) and partial dispersion ratios (θ1, θ2, θ3, θ4) of the lens units to satisfy specific conditional expressions. This allows correction of longitudinal chromatic aberration at the telephoto end through optimized optical parameters rather than increasing system complexity
Solution Approach 2:
The zoom lens system is divided into four distinct lens units with specific functions: the first lens unit for chromatic aberration correction, the second for magnification variation, the third for image plane correction, and the fourth for final image formation. This segmentation allows each unit to be optimized independently for its specific function
2Measurement precision
If lens units are added or modified to correct longitudinal chromatic aberration, then optical performance improves, but the size and weight of the zoom lens system increase
Solution Approach 1:
The patent achieves chromatic aberration correction by optimizing the Abbe constants and partial dispersion ratios of existing lens units rather than adding more lens elements. The conditional expressions on ν and θ parameters enable effective correction while maintaining a compact design with controlled weight
3Measurement precision
If lens units are added or modified to correct longitudinal chromatic aberration, then optical performance improves, but the size of the zoom lens system increases
Solution Approach 1:
The patent uses parameter optimization of the four lens units (Abbe constants ν1-ν4 and partial dispersion ratios θ1-θ4) to correct chromatic aberration without increasing the physical length of the lens system. The conditional expressions ensure effective correction within a compact form factor
Solution Approach 2:
The first lens unit serves multiple functions: it corrects longitudinal chromatic aberration while also contributing to the overall magnification and focal length control of the system. This multi-functionality avoids the need for additional dedicated correction elements that would increase system length
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 effectively corrects secondary spectrum longitudinal chromatic aberration at the telephoto end while maintaining a small size and light weight, achieving high magnification and good optical performance.
Implementation Method 1
a first lens unit having a positive refractive power that does not move for magnification varying... when an Abbe constant of a positive lens Lp having a smallest Abbe constant among lenses constituting the first lens unit is denoted by vp, a partial dispersion ratio thereof is denoted by θp
Data Source
Figure 1~3
Figure 4A~4B
Figure 5
AI summary
A zoom lens system, including, in order from an object side: a first unit having a positive refractive power; a second unit having a negative refractive power that moves for magnification-varying; a third unit having one of a positive refractive power and a negative refractive power that moves for magnification-varying; and a fourth unit having a positive refractive power, in which: when an Abbe constant of a positive lens Lp having a smallest Abbe constant among lenses constituting the first unit is denoted by νp, a partial dispersion ratio thereof is denoted by θp, a refractive power thereof is denoted by ϕp, an average value of Abbe constants of positive lenses except the positive lens Lp is denoted by νap, an average value of partial dispersion ratios of negative lenses of the first unit is denoted by θan, a refractive power of the first unit is denoted by ϕ1, and a refractive power of an entire zoom lens system at a telephoto end is denoted by ϕtele, the following conditional expressions are satisfied: -0.03<θp-θan/θan<0.15; 0.005<1/νp-1/νap/φ1/φtele<0.030; and 0.05<φp/φ1<0.4.