Zoom Lens Aberration Correction via Segmented Negative Unit
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Solution Overview
Problem
Existing zoom lenses face challenges in achieving high optical performance while maintaining a compact and lightweight design, particularly in super wide-angle lenses, where proper correction of lateral chromatic aberration and field curvature is necessary, and the refractive power and dispersion characteristics of lens units must be carefully balanced to achieve both a wide angle of view and small size.
Innovation Solution
A zoom lens configuration with a first lens unit having negative refractive power and a rear group with positive refractive power, where the distance between lens units changes during zooming, and specific conditional expressions are satisfied to optimize the focal lengths and refractive indices of lens units, ensuring well-corrected aberrations and a compact optical system.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Shape
If a retrofocus type configuration with a negative lens unit on the object side is used to achieve a wide angle of view, then the angle of view is widened, but the lens size and weight increase
Solution Approach 1:
The first lens unit is divided into multiple lens elements (including at least three negative lenses and at least one positive lens) arranged in sequence. This segmentation allows the negative refractive power to be distributed across multiple smaller elements rather than requiring a single large negative lens, thereby achieving the wide angle of view while reducing overall lens weight and size.
Solution Approach 2:
Different lens elements within the first lens unit have different refractive powers and dispersion characteristics. The negative lenses (with negative refractive power) are positioned to correct lateral chromatic aberration, while positive lenses are positioned to correct field curvature. This local optimization of optical properties allows effective aberration correction with a compact design.
2Shape
If a retrofocus type configuration with a negative lens unit on the object side is used to achieve a wide angle of view, then the angle of view is widened, but the lens complexity increases
Solution Approach 1:
The zoom lens is divided into distinct functional groups: the first lens unit (with negative refractive power for wide angle and aberration correction) and the rear group (with positive refractive power for focusing and additional correction). This clear segmentation of functions simplifies the design process and makes the complex system more manageable compared to a monolithic design.
Solution Approach 2:
The first lens unit serves multiple functions simultaneously: it provides the negative refractive power necessary for wide angle of view, corrects lateral chromatic aberration through its negative lenses, and corrects field curvature through its positive lenses. This multi-functionality reduces the need for additional separate correction elements, thereby managing complexity.
3Length of stationary object
If the refractive power and dispersion characteristics of lens units are optimized for compact size, then the lens becomes smaller, but optical performance deteriorates
Solution Approach 1:
The patent specifies particular arrangements of lenses with different dispersion characteristics within the first lens unit. At least three negative lenses and at least one positive lens are arranged in sequence, with specific conditional expressions governing their focal lengths and positions. This local optimization ensures that aberrations are corrected effectively within the compact form factor.
Solution Approach 2:
The patent defines specific conditional expressions for the focal lengths of the first lens unit (f1) and the rear group (fR), as well as for the focal lengths of individual lens elements (fG1N, fG1P, etc.). By carefully controlling these optical parameters within specified ranges, the design achieves both compact size and high optical performance across the entire zoom range.
4Reliability
If aberration correction is improved through proper lens unit configuration, then optical performance increases, but the lens size increases
Solution Approach 1:
Aberration correction is achieved through segmentation of the first lens unit into multiple specialized elements rather than using a single large correction element. The negative lenses correct lateral chromatic aberration while positive lenses correct field curvature, allowing effective aberration control in a compact arrangement.
Solution Approach 2:
The patent employs specific conditional expressions that define the relationships between focal lengths of different lens elements (e.g., |f1|/fw between 1.93 and 6.50, fG1N/f1 between 0.10 and 0.50). These parameter constraints ensure that aberration correction is achieved efficiently without requiring excessive lens length, maintaining a compact design.
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 enables a zoom lens with a wide angle of view, compact size, and high optical performance across the entire zoom range, effectively correcting chromatic aberrations and maintaining a small overall length, while allowing for a wider angle of view exceeding 100° at the wide-angle end.
Implementation Method 1
a first lens unit L1 having a negative refractive power
Implementation Method 2
a rear group LR having a positive refractive power as a whole including at least one lens unit
Implementation Method 3
it becomes necessary to properly correct a lateral chromatic aberration and a field curvature
Implementation Method 4
it becomes necessary to properly correct a lateral chromatic aberration and a field curvature
Data Source
AI summary
A zoom lens includes, in order from an object side to an image side, a first lens unit having a negative refractive power, and a rear group having a positive refractive power as a whole including at least one lens unit. During zooming from a wide-angle end to a telephoto end, a distance between adjacent lens units changes. The first lens unit includes at least three negative single lenses, and a predetermined condition is satisfied.