Compact Wide-Angle Imaging Lens With Moving Positive Group
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Solution Overview
Problem
There is a demand for an imaging lens with a small size, small F number, and wide angle of view while maintaining favorable optical performance, which existing technologies have not adequately addressed.
Innovation Solution
The imaging lens is designed with a configuration that includes a first lens group with negative refractive power and a second lens group with positive refractive power, where only the second lens group moves during focusing, and is optimized by a set of conditional expressions to achieve the desired characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of moving object
If the lens is designed with a small size and wide angle of view, then the field of view is improved, but the optical performance deteriorates
Solution Approach 1:
The lens is divided into multiple lens groups (first lens group with negative refractive power, second lens group with positive refractive power, and third lens group with positive refractive power), where each group is responsible for specific optical functions. This segmentation allows the lens to achieve wide angle of view while maintaining optical performance through specialized optimization of each group.
Solution Approach 2:
Different regions of the lens system are assigned different refractive powers and optical characteristics. The first lens group provides negative refractive power for wide angle coverage, the second lens group provides positive refractive power for focusing, and the third lens group provides additional positive refractive power for correction. This local differentiation of optical properties enables simultaneous achievement of wide field of view and high optical quality.
2Illumination intensity
If the F number is reduced to increase light gathering capability, then the light collection is improved, but the lens size and complexity increase
Solution Approach 1:
The second lens group is designed to move along the optical axis during focusing, enabling dynamic adjustment of the lens system. This dynamic capability allows the lens to achieve small F number and wide angle of view while maintaining compact size, as the moving lens group can optimize the optical path without requiring increased structural complexity.
3Speed
If a complex focusing mechanism is used to achieve fast focusing speed, then the focusing performance is improved, but the device complexity increases
Solution Approach 1:
The focusing function is extracted and assigned to a specific lens group (the second lens group with positive refractive power), which moves independently along the optical axis. This extraction allows the focusing mechanism to be simplified, as only one lens group needs to move rather than the entire lens system, thereby achieving fast focusing speed with reduced device complexity.
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 lens achieves a small size, small F number, and wide angle of view while maintaining excellent optical performance, with improved focusing speed 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 ω, 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.