Zoom Lens Group GR Segmentation for Chromatic Aberration Correction
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Solution Overview
Problem
Conventional zoom lenses face challenges in achieving a wide angle of view, high zoom ratio, and high optical performance while being compact in size and weight, particularly with the increasing demand for high-resolution image sensors like 4K and 8K.
Innovation Solution
The zoom lens configuration includes a first lens group not moving for zooming with positive refractive power, a middle group with multiple lens groups moving for zooming, and a lens group GR with a positive refractive power that does not move, featuring subgroups with negative and positive refractive powers and a specific Abbe number relationship, along with conditional inequalities to optimize optical performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a positive lead type zoom lens with a first lens group having positive refractive power and a second lens group having negative refractive power is used, then the angle of view is widened and zoom ratio is increased, but the optical performance deteriorates and size reduction becomes difficult
Solution Approach 1:
The lens group GR is divided into two subgroups: GRN (negative refractive power) and GRP (positive refractive power). This segmentation allows independent optimization of each subgroup's optical characteristics, enabling better chromatic aberration correction while maintaining the overall positive refractive power needed for wide angle of view and high zoom ratio.
Solution Approach 2:
Different materials with specific Abbe numbers are selected for the subgroups GRN and GRP to address local optical quality issues. The negative subgroup GRN uses materials with lower Abbe numbers while the positive subgroup GRP uses materials with higher Abbe numbers, creating local quality differences that effectively correct chromatic aberrations in specific regions of the optical system.
2Measurement precision
If high-resolution image sensors (4K, 8K) are used, then image quality is improved, but the requirement for resolving power and chromatic aberration correction becomes more stringent
Solution Approach 1:
The patent specifies precise parameter ranges for the Abbe numbers of materials used in subgroups GRN and GRP, along with specific conditional inequalities that must be satisfied. By controlling these optical parameters within defined ranges, the lens achieves the resolving power and chromatic aberration correction necessary for high-resolution 4K and 8K image sensors.
3Reliability
If the lens group GR consists of subgroups with negative and positive refractive powers arranged with the longest air gap, then chromatic aberrations are corrected, but the structural complexity increases
Solution Approach 1:
Instead of arranging the positive subgroup GRP first and then the negative subgroup GRN, the patent inverts the conventional arrangement by placing the negative subgroup GRN first (closest to object side) and the positive subgroup GRP second. This inverted arrangement, combined with positioning the aperture stop between them, achieves effective chromatic aberration correction while maintaining a relatively simple overall structure.
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 configuration results in a zoom lens that is small in size and weight, offering a wide angle of view, high zoom ratio, and superior optical performance by effectively correcting chromatic aberrations and maintaining optical quality across the image field.
Implementation Method 1
a first lens group arranged closest to an object side, configured not to move for zooming, and having a positive refractive power... and a lens group GR arranged closest to an image side, configured not to move for zooming, and having a positive refractive power
Implementation Method 2
the lens group GR consists of a subgroup GRN having a negative refractive power and a subgroup GRP having a positive refractive power... wherein νdGRNn is an average value of an Abbe number with reference to a d-line of a material of a negative lens in the subgroup GRN, νdGRNp is an average value of an Abbe number with reference to a d-line of a material of a positive lens in the subgroup GRN
Data Source
AI summary
A zoom lens includes a first lens group arranged closest to an object side, configured not to move for zooming, and having a positive refractive power, a lens group GR arranged closest to an image side, configured not to move for zooming, and having a positive refractive power, and a lens group GP arranged adjacent to the object side of the lens group GR, configured to move for zooming, and having a positive refractive power, wherein the lens group GR consists of a subgroup GRN having a negative refractive power and a subgroup GRP having a positive refractive power, which are arranged with a longest air gap on an optical axis in the lens group GR, and configuration of the subgroup GRN and a lateral magnification of the lens group GR are appropriately set.