Compact Imaging Lens with Segmented Groups for Wide Angle
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Solution Overview
Problem
Existing imaging lenses with a small number of lenses fail to achieve a balance between wide angle of view and compactness while maintaining high optical performance, especially for high pixel count and high performance image sensors, due to issues like large chromatic aberration and astigmatism, and often sacrifice compactness for brightness.
Innovation Solution
The design of an imaging lens comprising a first lens group with negative refractive power and a second lens group with positive refractive power, specifically configured to satisfy certain conditional expressions regarding focal lengths, distances, and Abbe numbers, to achieve a compact, wide-angle, and bright optical system with improved aberration correction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If a small number of lenses is used to achieve compactness, then the device size is reduced, but optical performance deteriorates due to large chromatic aberration and astigmatism
Solution Approach 1:
The lens system is segmented into two distinct groups: a first lens group with negative refractive power and a second lens group with positive refractive power. This segmentation allows each group to be optimized for specific functions, with the negative group controlling aberrations and the positive group providing focusing power, thereby achieving high optical performance in a compact design.
Solution Approach 2:
The patent applies specific conditional expressions that define precise parameter ranges: the ratio of focal lengths (f1/f) must be between -0.89 and -0.67, the distance between lens groups (dk2/f) must be between 0 and 0.5, and the Abbe number of the first lens group (νd1) must be between 38 and 70. These parameter changes optimize the balance between compactness and optical performance.
2Illumination intensity
If the F-number is reduced to increase brightness, then light gathering capability is improved, but aberration correction becomes more difficult to maintain
Solution Approach 1:
The patent optimizes the F-number parameter to achieve brightness while maintaining aberration correction. By controlling the focal length ratio (f1/f) within -0.89 to -0.67 and the Abbe number (νd1) within 38 to 70, the system achieves an F-number of approximately 2.0, which provides sufficient brightness while maintaining well-corrected aberrations.
Solution Approach 2:
The lens system uses composite optical characteristics by combining lenses with different refractive powers and Abbe numbers. The first lens group has higher Abbe number (38-70) for aberration control, while the second lens group provides complementary optical properties, creating a composite optical system that achieves both brightness and aberration correction.
3Adaptability or versatility
If the angle of view is increased to achieve wide angle, then the field of view is expanded, but the lens design becomes more complex
Solution Approach 1:
The lens is segmented into two functional groups that work together to achieve wide angle of view. The first lens group with negative refractive power expands the field of view, while the second lens group with positive refractive power provides focusing and aberration correction. This segmentation achieves wide angle without requiring a complex multi-element design.
Solution Approach 2:
The patent uses specific parameter ranges to achieve wide angle of view: the focal length ratio (f1/f) is controlled between -0.89 and -0.67, and the distance parameter (dk2/f) is controlled between 0 and 0.5. These parameter changes enable the lens to achieve approximately 84 degrees of half-angle of view while maintaining a relatively simple two-group 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 solution enables the creation of a compact imaging lens with a wide angle of view and high optical performance, well-corrected for aberrations, suitable for high pixel count image sensors with an F-number of about 2.0, maintaining a balance between spherical and image plane aberrations.
Implementation Method 1
an imaging lens substantially consisting of a first lens group having a negative refractive power and a second lens group having a positive refractive power, disposed in order from the object side
Data Source
AI summary
An imaging lens provided with a negative first lens group and a positive second lens group arranged in order from the object side. The first lens group is composed of a first group first lens which is a negative single lens, and the second lens group is composed of a positive second group first lens, a positive second group second lens, and a negative second group third lens arranged in order from the object side. The second group first lens is a biconvex lens, the second group second lens is a biconvex lens, the second group third lens is a meniscus lens, an aperture stop is disposed between the second group first and second lenses, and the second group second and third lenses form a cemented lens. The imaging lens satisfies conditional expressions (1): −0.89≦f1/f<0 and (4): 0.3<dt1/f<0.8.