Wide-Angle Imaging Lens with Single-Group Focusing
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Solution Overview
Problem
Existing imaging lenses face challenges in achieving a small size, small F number, and wide angle of view while maintaining favorable optical performance.
Innovation Solution
The imaging lens is configured with a first lens group having negative refractive power and a second lens group with positive refractive power, where only the second lens group moves during focusing, satisfying specific conditional expressions to optimize optical performance and size.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If the imaging lens uses a conventional structure with multiple moving lens groups, then the focusing capability is maintained, but the device complexity and weight increase
Solution Approach 1:
The patent extracts and isolates the focusing function to a single dedicated lens group (the second lens group with positive refractive power), while keeping the first lens group (with negative refractive power) stationary. This separation allows the focusing mechanism to be simplified to only moving the second lens group, reducing overall device complexity while maintaining focusing capability through the isolated moving component.
2Volume of moving object
If the imaging lens is designed for compact size, then the overall dimensions are reduced, but the optical performance deteriorates
Solution Approach 1:
The patent segments the lens system into two distinct functional groups: the first lens group (negative refractive power) that remains stationary and provides optical correction, and the second lens group (positive refractive power) that moves during focusing. This segmentation allows each group to be optimized independently - the first group can be compact for size reduction while the second group handles focusing functionality, maintaining overall optical performance in a compact configuration.
3Illumination intensity
If the F number is reduced for better light gathering, then the aperture is enlarged, but the optical performance and size control become difficult
Solution Approach 1:
The patent applies local quality by assigning different refractive power characteristics to different lens groups: the first lens group has negative refractive power for optical correction and size control, while the second lens group has positive refractive power for focusing. This local differentiation allows the aperture to be optimized for light gathering (small F number) while the negative power group compensates for aberrations and controls overall system size, maintaining optical performance.
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 achieves a small size, small F number, and wide angle of view while maintaining favorable optical performance, with reduced weight and simplified focusing mechanisms.
Implementation Method 1
a first lens group G1 that has a negative refractive power; and a second lens group G2 that has a positive refractive power
Data Source
AI summary
An imaging lens includes, in order from the object side, a first lens group that has a negative refractive power and a second lens group that has a positive refractive power. During focusing, only the second lens group moves. The first lens group includes three negative lenses successively in order from a position closest to the object side. Assuming that an open F number is FNo, a maximum half angle of view is w, a back focal length is Bf, and a focal length of the whole system f, the imaging lens satisfies 0.8<FNo/tan ω<1.9 and 0.3<Bf/(f×tan ω))<1.2.