Compact Zoom Lens Layout for High Zoom Ratio and Aberration Stability
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Solution Overview
Problem
There is a demand for a zoom lens that is small in size and light in weight while achieving a high zoom ratio, which existing technologies have not adequately addressed.
Innovation Solution
A zoom lens configuration comprising a first lens group with positive refractive power, a second lens group with negative refractive power, and a subsequent group with multiple lens groups, where the aperture stop is positioned closer to the image side than the lens surface of the second lens group, and specific conditional expressions are satisfied to optimize lens spacings and refractive indices for achieving a high zoom ratio and reduced size.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a high zoom ratio is achieved by conventional lens configurations, then the zoom capability is improved, but the lens size and weight increase
Solution Approach 1:
The lens is divided into three distinct groups (first lens group with positive power, second lens group with negative power, and subsequent group with multiple lens groups). This segmentation allows each group to be optimized independently for its specific function while contributing to the overall high zoom ratio, thereby reducing the total weight compared to a monolithic lens design.
Solution Approach 2:
The aperture stop is positioned in a novel location - closer to the image side than the lens surface closest to the image side in the second lens group. This unconventional positioning in the optical path dimension enables improved light control and aberration correction, allowing for a more compact lens design that achieves high zoom ratio without proportional weight increase.
2Adaptability or versatility
If a high zoom ratio is achieved by conventional lens configurations, then the zoom capability is improved, but the lens size increases
Solution Approach 1:
During zooming, the spacing between the first lens group and the second lens group changes, the spacing between the second lens group and the subsequent group changes, and the spacings between all adjacent lens groups in the subsequent group change. This dynamic adjustment of multiple spacings simultaneously enables a compact lens structure that achieves high zoom ratio without excessive length increase.
Solution Approach 2:
The patent specifies precise conditional expressions for focal lengths (fw, ft), distances (Denw, Dexw), and spacings (D1, TLt) that must be satisfied to achieve the optimal balance between zoom ratio and lens length. By carefully controlling these optical parameters within defined ranges, the lens achieves high zoom capability while maintaining a compact form factor.
3Adaptability or versatility
If lens groups are moved during zooming to change focal length, then the zoom function is improved, but chromatic aberrations and aberration fluctuations increase
Solution Approach 1:
The second lens group with negative refractive power acts as an intermediary between the first positive lens group and the subsequent lens groups. This negative power group compensates for chromatic aberrations introduced by the positive power groups during zooming operations, thereby maintaining aberration stability while enabling the zoom function.
Solution Approach 2:
Instead of relying solely on mechanical lens group movements to achieve zoom, the patent uses optical power distribution and spacing adjustments among the three lens groups to achieve both zoom and aberration correction. The specific arrangement and power distribution of the lens groups substitute for complex mechanical aberration correction mechanisms.
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 high zoom ratio and reduced size, while minimizing chromatic aberrations and fluctuations in aberrations during focusing, thereby achieving a compact and lightweight imaging apparatus.
Implementation Method 1
a first lens group G1 that has a positive refractive power, a second lens group G2 that has a negative refractive power
Data Source
AI summary
A zoom lens consisting of, in order from an object side to an image side: a first lens group that has a positive refractive power; a second lens group that has a negative refractive power; and a subsequent group that has a plurality of lens groups, wherein: the zoom lens includes an aperture stop at a position closer to the image side than a lens surface closest to the image side in the second lens group, a lens group closest to the image side in the subsequent group includes at least one negative lens of which an object side lens surface is a concave surface being in contact with air, during zooming, a spacing between the first lens group and the second lens group changes, a spacing between the second lens group and the subsequent group changes, and spacings between all adjacent lens groups in the subsequent group change.