Wide-Angle Optical System Aspheric Third Lens Peripheral Sensitivity
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Solution Overview
Problem
Current wide-angle optical systems for camera modules in compact devices face challenges in maintaining image quality and sensitivity at the periphery while minimizing the optical system's length, leading to issues like chromatic aberrations and sensitivity drops.
Innovation Solution
A wide-angle optical system comprising a stop, a positive refracting first lens, a negative refracting second lens, and an aspheric third lens, with specific configurations and conditions to ensure the system's compactness and peripheral sensitivity, including meniscus-shaped surfaces and optimized refractive indices and curvatures, which helps in reducing chromatic aberrations and maintaining image quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of stationary object
If the optical system length is reduced to meet compact device demands, then the device size is reduced, but chromatic aberrations increase and image quality deteriorates
Solution Approach 1:
The optical system is divided into multiple lens components (first lens, second lens, third lens) with distinct functions. The first lens handles positive refraction, the second lens handles negative refraction for chromatic aberration correction, and the third lens provides additional focusing power. This segmentation allows each component to be optimized for its specific function while maintaining a compact overall length.
Solution Approach 2:
The patent employs composite lens structures combining different materials with varying refractive indices and Abbe constants. Specifically, the second lens uses a material with high dispersion (low Abbe constant) to counteract chromatic aberrations introduced by other lenses. This composite approach enables chromatic aberration correction within a shortened optical path.
2Length of stationary object
If the exit pupil position is moved closer to the imaging device side to reduce total length, then the optical system length is reduced, but peripheral sensitivity drops
Solution Approach 1:
The third lens is designed with asymmetric surface curvatures where the object-side surface has a different curvature radius (R7) compared to the image-side surface (R8). This local variation in optical properties allows the lens to maintain proper light ray angles at the periphery even with the exit pupil positioned closer to the imaging device, thereby preserving peripheral sensitivity.
Solution Approach 2:
The patent utilizes aspheric surfaces on the third lens with specifically designed curvature radii. The object-side surface curvature (R7) and image-side surface curvature (R8) are optimized to control light ray paths, ensuring that even with a shortened optical system and shifted exit pupil, off-axis rays maintain appropriate angles of incidence on the imaging device, preserving peripheral sensitivity.
3Device complexity
If only two or three simple lenses are used to reduce complexity, then the device complexity is reduced, but chromatic aberration correction becomes insufficient
Solution Approach 1:
The patent carefully selects and optimizes key parameters including the Abbe constant of the second lens (v2 between 10-30) to ensure adequate chromatic aberration correction. The focal lengths (f1, f2, f3) and curvature radii (R1-R8) are precisely controlled within specified ranges to balance chromatic aberration correction with compact system length, achieving effective correction with only three lens components.
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 effective correction of chromatic aberrations and sensitivity drops at the periphery, allowing for compact camera modules with improved image quality and reduced optical system size, while maintaining peripheral performance.
Implementation Method 1
a third lens that is an aspheric lens, wherein said third lens is configured such that as viewed in a lens section including an optical axis, a portion thereof near said optical axis is in a meniscus shape convex on an object side
Implementation Method 2
a first lens having positive refracting power, a second lens having negative refracting power
Data Source
AI summary
A wide-angle optical system comprises, in order from its object side, a stop, a first lens (L1) having positive refracting power, a second lens (L2) having negative refracting power and a third lens (L3) that is an aspheric lens. The third lens is configured such that as viewed in a lens section including an optical axis, a portion thereof near the optical axis is in a meniscus shape convex on an object side thereof, and an object side surface and an image side surface thereof at a peripheral site are in a meniscus shape convex on an image side thereof. The optical system satisfies the following conditions (1-1) and (1-2).−0.40<f/f3<0.15 (1-1)0.30<hc7/hp7<2.0 (1-2)where f is the focal length of the whole wide-angle optical system, and f3 is the focal length of the third lens. When Lm stands for a light ray passing through the center of the stop at an angle of 36° with the optical axis, and Pm7 stands for a point at which Lm passes the image side surface of the third lens, hc7 is supposed to be a distance from Pm7 to the optical axis, and hp7 is supposed to be a distance from a convex apex Pp7 of the image side surface of the third lens to the optical axis.