Three-Piece Optical Lens System with Negative Third Element
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Solution Overview
Problem
Conventional miniaturized optical lens systems with three-piece configurations face challenges in miniaturization and image quality, particularly in the periphery, due to a long back focal length and large mechanical structure, which compromises image resolution and field of view.
Innovation Solution
A three-piece optical lens system is designed with specific refractive powers and aspheric surfaces for the first, second, and third lens elements, where the refractive index and Abbe number of the third lens element satisfy certain conditions, and the focal length ratios between elements are optimized to reduce volume, flatten image edges, and improve peripheral image quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the third lens element has positive refractive power, then the principal point is close to the image side, but the back focal length becomes relatively long resulting in large mechanical structure
Solution Approach 1:
The patent changes the refractive power sign of the third lens element from positive to negative, which fundamentally alters the optical path and moves the principal point to the object side, thereby shortening the back focal length and reducing the overall mechanical structure size
2Length of stationary object
If the back focal length is relatively long, then the mechanical structure is large, but the miniaturization requirement cannot be satisfied
Solution Approach 1:
By changing the refractive power of the third lens element to negative and optimizing the focal length ratios between elements, the patent achieves a short back focal length which directly reduces the mechanical structure volume and enables miniaturization
3Volume of stationary object
If the mechanical structure is large, then the system can accommodate the optical elements, but the image quality of the periphery of the image is reduced
Solution Approach 1:
The patent optimizes multiple parameters including the refractive power of the third lens element, the focal length ratios between elements, and the refractive index and Abbe number of the third lens element to flatten the image edge and improve peripheral image quality while maintaining a compact structure
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 optimized lens system achieves a reduced volume, improved image resolution, and enhanced peripheral image quality by providing a wide field of view while maintaining a short total track length, thus addressing the limitations of conventional systems.
Implementation Method 1
a first lens element with a positive refractive power having a convex object-side surface, at least one of the object-side and an image-side surfaces of the first lens element being aspheric
Implementation Method 2
at least one of the object-side and an image-side surfaces of the first lens element being aspheric
Implementation Method 3
a stop
Implementation Method 4
the refractive index of the third lens element is N3, the Abbe number of the third lens element is V3, and they satisfy the relations: N3>1.57; V3<23
Data Source
AI summary
A three-piece optical lens system comprises, in order from the object side to the image side: a first lens element with a positive refractive power having a convex object-side surface, one of the object-side surface and an image-side surface being aspheric; a stop, a second lens element with a positive refractive power having a concave object-side surface, one of the object-side surface and an image-side surface being aspheric; a third lens element with a negative refractive power having a concave image-side surface, one of an object-side surface and the image-side surface being aspheric. A refractive index of the third lens element is N3, an Abbe number of the third lens element is V3, and they satisfy the relations: N3>1.57; V3<40. Such arrangements can reduce the volume of the three-piece optical lens system and improve the image quality of the periphery of the image.