Variable Magnification Optical System Aberration Correction
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Solution Overview
Problem
Current variable magnification optical systems for cameras and projectors suffer from inadequate correction of various aberrations, including chromatic aberration, which affects image quality and performance.
Innovation Solution
A variable magnification optical system comprising specific lens groups with carefully selected refractive indices, Abbe numbers, and partial dispersion ratios, where the lens groups are arranged to optimize aberration correction, including the use of LA and LB lenses that satisfy specific conditional expressions to ensure effective chromatic and spherical aberration control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional lens systems are used, then the structure is simple, but various aberrations including chromatic aberration are not sufficiently corrected
Solution Approach 1:
The patent applies parameter changes by carefully selecting and optimizing the refractive indices (Nd1, Nd2, Nd3, Nd4), Abbe numbers (νd1, νd2, νd3, νd4), and partial dispersion ratios (θgF1, θgF2, θgF3, θgF4) of the lens elements. Multiple conditional expressions define specific ranges for these optical parameters to achieve superior aberration correction. For example, the first lens group satisfies conditions involving Nd1, νd1, and θgF1, while the second lens group satisfies conditions involving Nd2, νd2, and θgF2, thereby resolving the contradiction between maintaining relatively simple structure and achieving high aberration correction performance.
2Manufacturing precision
If more lens groups are added to improve aberration correction, then optical performance improves, but the system becomes more complex and larger
Solution Approach 1:
The patent applies local quality by assigning specific optical characteristics to different lens groups. Each lens group (first, second, third, and fourth) has distinct refractive index ranges, Abbe number ranges, and partial dispersion ratio ranges tailored to its position and function in the optical system. For instance, the first lens group uses materials with specific Nd1 and νd1 values to correct certain aberrations, while the second lens group uses different Nd2 and νd2 values for complementary correction, thereby achieving high overall performance without unnecessarily increasing system length.
3Manufacturing precision
If lens materials are optimized for aberration correction, then image quality improves, but manufacturing difficulty increases
Solution Approach 1:
The patent defines specific parameter ranges for refractive indices (Nd1: 1.80-2.20, Nd2: 1.45-1.70, Nd3: 1.80-2.00, Nd4: 1.50-1.70), Abbe numbers (νd1: 20-40, νd2: 25-50, νd3: 25-35, νd4: 30-50), and partial dispersion ratios (θgF1: 0.55-0.65, θgF2: 0.50-0.60, θgF3: 0.55-0.65, θgF4: 0.50-0.60) that balance optical performance with manufacturability. These standardized ranges make it feasible to select from commercially available optical materials while achieving superior aberration correction, thus resolving the contradiction between manufacturing precision and ease of manufacture.
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 system achieves high optical performance by satisfactorily correcting various aberrations, leading to improved image quality and magnification capabilities while maintaining a compact design.
Implementation Method 1
a first lens group having a positive refractive power which is disposed at a position closest to the object side; a variable magnification lens group which is disposed at a position closest to the object side among lens groups having a negative refractive power and moves during changing magnification
Data Source
AI summary
The variable magnification optical system includes, in order from an object side, a positive first lens group disposed at a position closest to the object side, a variable magnification lens group which is disposed at a position closest to the object side among negative lens groups and moves during changing magnification, an intermediate group including at least one lens group, and a positive final lens group which is disposed at a position closest to the image side. The variable magnification lens group, the intermediate group, and the final lens group are continuously disposed. The variable magnification optical system includes at least one LA lens. This LA lens satisfies predetermined conditional expressions relating to a refractive index, an Abbe number, and a partial dispersion ratio, and is located from the variable magnification lens group to the intermediate group.