Four-Lens Imaging System Aberration Correction
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Solution Overview
Problem
Conventional wide-angle imaging lenses face challenges in achieving a balance between small size, high resolution, wide angle of view, and cost-effectiveness, while also being sensitive to manufacturing errors and temperature fluctuations, particularly in compact camera systems like onboard cameras.
Innovation Solution
The imaging lens configuration includes a first lens with negative refractive power, a second lens with positive refractive power, a third lens with positive refractive power, and a fourth lens with positive refractive power, arranged in a specific order, with focal length and Abbe's number constraints that allow for balanced chromatic aberration, distortion, and field curvature correction, while using resin materials for three lenses and glass for the fourth to minimize temperature effects.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If the size of imaging lens is reduced, then compact size is achieved, but refractive power of each lens becomes stronger and aberration correction becomes difficult
Solution Approach 1:
The imaging lens is divided into multiple lens units (first through fourth lenses) with different refractive powers and Abbe's numbers. By segmenting the optical system into discrete elements with specific properties (negative first lens, positive second lens with low Abbe's number, positive third lens with high Abbe's number, positive fourth lens), the patent achieves aberration correction in a compact form factor without requiring each individual lens to have excessively strong refractive power.
Solution Approach 2:
The patent employs composite material selection by combining lenses made of different materials with varying Abbe's numbers (ranging from 23 to 85). This material diversity allows simultaneous correction of chromatic aberrations while maintaining compact dimensions, as each material contributes differently to the overall optical performance.
2Ease of manufacture
If the number of lenses is reduced, then manufacturing cost and assembly complexity are lowered, but it becomes difficult to satisfy high-resolution requirements and wide angle of view simultaneously
Solution Approach 1:
The patent optimizes specific parameters including the Abbe's number ranges of lens materials (νd2: 23-40, νd3: 50-85), focal length ratios (f1/f within -5.0 to -1.0), and curvature radii relationships. These parameter constraints enable a four-lens design to achieve wide angle of view (≥135°) and high-resolution compatibility without requiring additional lens elements, thus maintaining manufacturing simplicity.
3Adaptability or versatility
If the first lens has very strong negative refractive power to achieve wide angle of view, then angle of view is widened, but curvature radius of image plane-side surface becomes small resulting in poor workability and high sensitivity to manufacturing errors
Solution Approach 1:
The patent specifies that the first lens has negative refractive power with focal length ratio f1/f within -5.0 to -1.0, and the image plane-side surface curvature radius r2 satisfies r2/r1 > 0.5. This parameter optimization balances the need for wide angle of view with manufacturability, avoiding excessively small curvature radii that would compromise workability and increase sensitivity to alignment errors.
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
This configuration enables a compact, high-resolution imaging lens with a wide angle of view, reduced manufacturing costs, and improved resistance to manufacturing errors and temperature fluctuations, ensuring satisfactory image-forming performance and cost-effectiveness.
Implementation Method 1
a first lens (L1) having negative refractive power
Implementation Method 2
a second lens (L2) having positive refractive power; a third lens (L3) having positive refractive power; a fourth lens (L4) having positive refractive power
Implementation Method 3
the second lens is made of a material having Abbe's number between 23 and 40, and the third lens is made of a material having Abbe's number between 50 and 85
Data Source
AI summary
An imaging lens includes a first lens having negative refractive power; a second lens having positive refractive power; a third lens having positive refractive power; and a fourth lens, arranged in this order from an object side to an image plane side. The second lens is arranged to face the third lens. The first lens has a focal length f1 and the fourth lens has an Abbe's number νd4 so that the specific conditional expressions are satisfied.