Compact Zoom Lens with Aspheric Correction for Chromatic Aberration
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Solution Overview
Problem
There is a demand for a compact zoom lens with a wide angle of view and corrected chromatic aberration, which existing zoom lenses have not effectively addressed.
Innovation Solution
A zoom lens configuration comprising a first lens group with negative refractive power, a second lens group with positive refractive power, and a third lens group, where the first lens group includes four lenses with specific refractive powers and Abbe numbers, and the second lens group incorporates at least one aspheric lens, allowing for reduced spacing between lens groups and improved refractive power distribution to correct aberrations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If a conventional zoom lens configuration is used, then the lens can achieve basic zoom functionality, but the lens size becomes large and chromatic aberration is not effectively corrected
Solution Approach 1:
The zoom lens is divided into three distinct lens groups (first with negative refractive power, second with positive refractive power, and third with positive refractive power), each serving specific optical functions. This segmentation allows independent optimization of each group for compactness and aberration correction, resolving the contradiction between small size and effective chromatic aberration correction
Solution Approach 2:
Specific lenses within the first lens group are assigned high Abbe numbers (v1>60, v2>60, v3>60) to locally enhance chromatic aberration correction capabilities in the negative power group, while the second lens group uses lenses with Abbe numbers greater than 60 to further correct chromatic aberration. This local quality assignment enables effective aberration correction in a compact configuration
2Volume of moving object
If the spacing between lens groups is reduced to make the lens compact, then the lens size decreases, but aberration correction becomes more difficult
Solution Approach 1:
The patent employs composite lens designs including doublets (combinations of two lenses) in the second lens group, where lenses with different refractive indices and Abbe numbers are combined. This composite approach enables effective aberration correction even with reduced spacing between lens groups, as the different material properties work together to correct various types of aberrations
Solution Approach 2:
At least one aspheric lens is incorporated in the second lens group to correct spherical aberration and other monochromatic aberrations. The aspheric surfaces provide additional degrees of freedom for aberration control, enabling effective correction despite the compact spacing between lens groups
3Adaptability or versatility
If a wide angle of view is achieved through conventional means, then the field of view increases, but the lens becomes less compact and aberration correction is compromised
Solution Approach 1:
The zoom lens employs dynamic spacing adjustment between lens groups during zoom operation. The spacing between the first and second lens groups changes as the focal length varies, allowing the lens to maintain a compact form factor across the entire zoom range while achieving a wide angle of view at the wide-angle end. This dynamic configuration enables the lens to adapt its optical path length to maintain compactness regardless of the angle of view
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 provides a compact zoom lens with a wide angle of view and high resolution, effectively correcting chromatic aberration and maintaining enhanced imaging characteristics across the focal length range.
Implementation Method 1
The second lens group can include, on the object side, at least one aspheric lens with positive refractive power
Implementation Method 2
When the Abbe numbers of the three lenses with negative refractive power in the first lens group are designated v1, v2, and v3, respectively, the following conditional expressions can be satisfied: v1>60, v2>60, v3>60
Data Source
AI summary
A zoom lens includes a first lens group with a negative refractive power, a second lens group with a positive refractive power, and a third lens group with a positive refractive power. When the zoom lens changes from a wide angle end to a telephoto end, a spacing between the first lens group and the second lens group is reduced, and a spacing between the second lens group and the third lens group changes. The first lens group includes a first lens, a second lens, a third lens, and a fourth lens. Refractive powers of the first lens, the second lens, and the third lens are negative, and a refractive power of the fourth lens is positive. Abbe numbers of the first lens, the second lens, and the third lens are larger than 60. A ratio of a focal length of the first lens group over a focal length of the zoom lens at a wide angle end is larger than −2.5 and smaller than −1.2.