Zoom Lens Compact Size Aberration Correction
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Solution Overview
Problem
Existing zoom lenses face challenges in achieving a balance between compact size and excellent optical performance, particularly in correcting spherical aberration, axial chromatic aberration, and curvature of field, due to the arrangement of negative refractive power lens units which can lead to increased Petzval sum and difficulty in size reduction.
Innovation Solution
A zoom lens configuration with a specific power arrangement and movement of lens units, including a first lens unit with positive refractive power, a second lens unit with negative refractive power, a third lens unit with positive refractive power, an intermediate lens group with at least one negative lens unit, and a last lens unit with negative refractive power, where the negative lens units move during zooming, and the aperture stop is positioned to optimize size reduction and image quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of moving object
If multiple negative refractive power lens units are disposed close to the image plane to reduce size, then the total lens length is reduced, but spherical aberration and axial chromatic aberration cannot be corrected effectively
Solution Approach 1:
The lens is divided into multiple lens units with different refractive powers (positive and negative) arranged in a specific sequence. By segmenting the optical system into discrete units (L1, L2, L3, Ln, LR) with alternating signs of refractive power, the patent achieves both compact size and effective aberration correction through the coordinated movement and power distribution of these segments.
Solution Approach 2:
Different lens units are assigned different refractive powers and positions to perform specific functions. The positive lens units (L1, L3) and negative lens units (L2, Ln, LR) are strategically positioned and powered to correct specific aberrations locally, with the negative units closer to the image plane controlling size while positive units contribute to aberration correction.
2Productivity
If multiple negative lens units are increased to achieve high magnification ratio, then the magnification ratio is improved, but the Petzval sum becomes large negative value making curvature of field correction difficult
Solution Approach 1:
The patent employs an asymmetric power distribution with alternating positive and negative lens units rather than a symmetric arrangement. The specific sequence (positive, negative, positive, negative..., negative) and the different positions of positive and negative units create an asymmetric configuration that achieves high magnification while controlling the Petzval sum to correct curvature of field.
Solution Approach 2:
The patent optimizes specific parameters including the focal lengths of individual lens units (f1, f2, f3, fLN, fLR), their movement amounts during zooming (ML1, ML3, MLN), and the position of the aperture stop to control the Petzval sum. By carefully adjusting these parameters, the system achieves high magnification ratio while maintaining excellent curvature of field correction.
3Length of moving object
If negative lens units are disposed close to the image plane for size reduction, then compact configuration is achieved, but the number of negative lens units increases making the system complex
Solution Approach 1:
The negative lens units in the patent serve multiple functions simultaneously: they contribute to the telephoto-type power arrangement for size reduction, participate in aberration correction through their strategic positioning, and enable high magnification ratio. This multi-functionality reduces the need for additional dedicated components, thereby managing system complexity.
Solution Approach 2:
The patent employs dynamic movement of lens units during zooming operations. The negative lens units (L2, Ln, LR) move along with positive lens units to maintain optimal optical performance across different focal lengths. This dynamic adjustment allows the system to achieve compact size at various zoom positions without requiring a fixed complex 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
The configuration ensures a high magnification ratio while reducing the size of the zoom lens, effectively correcting aberrations and achieving improved optical performance by setting specific ratios for focal lengths, movement amounts, and aperture stop positions.
Implementation Method 1
a first lens unit L1 having a positive refractive power, a second lens unit L2 having a negative refractive power, a third lens unit L3 having a positive refractive power, an intermediate lens group LM including a plurality of lens units, and a last lens unit LR having a negative refractive power
Data Source
Figure 1
Figure 2A~2B
Figure 3
AI summary
A zoom lens L0 includes a first lens unit L1 having a positive refractive power, a second lens unit L2 having a negative refractive power, a third lens unit L3 having a positive refractive power, an intermediate lens group LM including a plurality of lens units, and a last lens unit LR having a negative refractive power. An interval between the adjacent lens units changes during zooming. The zoom lens L0 includes an aperture stop SP. The intermediate lens group LM includes a negative lens unit LN having a negative refractive power. Both the negative lens unit LN and the last lens unit LR move to an object side during zooming from a wide-angle end to a telephoto end. The zoom lens L0 satisfies predetermined conditional inequalities.