Fisheye Lens System Using Inverted Refractive Groups
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Solution Overview
Problem
Fisheye lens systems face challenges in achieving a wide viewing angle of 180 degrees while maintaining appropriate power and resolution, as conventional projection methods do not apply, and existing designs struggle with miniaturization and aberration compensation.
Innovation Solution
A miniaturized fisheye lens system is designed with specific lens group configurations, including a first lens group with negative refractive power and a second lens group with positive refractive power, optimized by shaping factors, focal length ratios, and aperture placement, to achieve a wide viewing angle and high resolution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a fisheye lens system uses conventional projection methods (Y=f×tan θ) to achieve a wide viewing angle, then the viewing angle can be increased, but the system cannot maintain appropriate power and resolution
Solution Approach 1:
The patent changes the projection parameter from conventional tan θ to alternative projections (Y=f×θ, Y=f×sin θ, or Y=f×tan(θ/2)), enabling 180-degree viewing angle while maintaining image quality and resolution through modified optical path geometry
2Manufacturing precision
If a fisheye lens system increases the number of lenses to improve resolution and compensate for aberrations, then image quality improves, but the system size increases and miniaturization becomes difficult
Solution Approach 1:
The patent applies different shaping factors (SF) to different lens groups: the first lens group uses 0.4≤SF≤0.6 and the second lens group uses 0.3≤SF≤0.5, optimizing each group's contribution to aberration compensation and resolution while controlling overall system size
Solution Approach 2:
The patent divides the lens system into two functional groups: a first lens group with negative refractive power for wide-angle light gathering and a second lens group with positive refractive power for focal length control and aberration correction, enabling compact 180-degree fisheye imaging
3Volume of moving object
If a fisheye lens system reduces the number of lenses to achieve miniaturization, then system size decreases, but aberration compensation becomes insufficient and image quality deteriorates
Solution Approach 1:
The patent optimizes the shaping factor parameter within specific ranges (0.4≤SF≤0.6 for first group, 0.3≤SF≤0.5 for second group) to achieve effective aberration compensation with minimal lens elements, enabling compact design without sacrificing image quality
4Volume of moving object
If a fisheye lens system uses a short back focal length to achieve miniaturization, then system size decreases, but the lens cannot maintain sufficient back focal length for proper image formation
Solution Approach 1:
The patent inverts the conventional lens arrangement by placing the negative refractive power group closer to the object and the positive refractive power group closer to the image plane, creating a folded optical path that achieves short overall length while maintaining sufficient back focal length for proper image formation
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 system achieves a miniaturized, high-performance fisheye lens with improved peripheral and central resolution, capable of compensating for aberrations and maintaining a sufficient back focal length, suitable for applications like CCTV and digital cameras.
Implementation Method 1
a first lens group (G1) having negative refractive power
Implementation Method 2
a second lens group (G2) having positive refractive power
Implementation Method 3
R1i is a radius of curvature of a surface of an object side of the ith lens, and R2i is a radius of curvature of a surface of an image side of the ith lens
Data Source
AI summary
A fisheye lens system and a photographing apparatus including the fisheye lens system. The fisheye lens system includes, in an order from an object to an image, a first lens group including at least three lenses and having negative refractive power; and a second lens group having positive refractive power, wherein the at least three lenses included in the first lens group include a first lens, a second lens, and a third lens, in the order from the object to the image.