Three-Lens Optical System with Aspheric Inflection Points for Aberration Control
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Solution Overview
Problem
Conventional compact photographing optical lens systems face challenges in achieving high image quality while maintaining compactness and reducing sensitivity, as they often struggle with aberration correction and brightness due to the limited number of lens elements.
Innovation Solution
A three-lens-element optical lens system is designed with specific refractive powers and surface curvatures, including a first lens element with positive refractive power, a second lens element with positive or negative refractive power, and a third lens element with positive refractive power, along with an aperture stop between the object and the second lens element, to balance refractive power distribution and correct aberrations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a conventional two-lens-element system is used to reduce costs, then manufacturing cost is reduced, but the ability to correct aberration is limited and image quality deteriorates
Solution Approach 1:
The patent changes the parameters of the lens elements by using aspheric surfaces with inflection points and specific refractive power distributions. The third lens element has aspheric surfaces with inflection points that enable better aberration correction compared to conventional spherical surfaces, while the specific focal length ratios (0.23<f3/f<0.35 and 0.40<f1/f<0.70) optimize the balance between manufacturing feasibility and image quality
Solution Approach 2:
The patent employs composite optical design by combining lens elements with different properties: the first and second lens elements with positive refractive power and the third lens element with aspheric surfaces containing inflection points. This composite structure achieves superior aberration correction that would be impossible with simple two-element systems, while maintaining reasonable manufacturing complexity
2Length of stationary object
If a three-lens-element system with bi-concave third lens element is used to maintain compactness, then total track length is reduced, but the distance between exit pupil and image plane decreases causing increased chief ray incident angle and reduced brightness
Solution Approach 1:
Instead of using a bi-concave third lens element as in conventional designs, the patent inverts the approach by giving the third lens element positive refractive power with aspheric surfaces containing inflection points. This inversion allows the system to maintain compact total track length while simultaneously increasing the distance between exit pupil and image plane, thereby reducing chief ray incident angles and improving brightness
Solution Approach 2:
The patent changes the critical parameter of the third lens element from bi-concave to aspheric with inflection points and positive refractive power. This parameter change fundamentally alters the optical path, enabling the exit pupil to be positioned farther from the image plane while maintaining compact overall length, thus resolving the brightness issue without sacrificing compactness
3Manufacturing precision
If lens systems with more than two lens elements are used to improve image quality, then aberration correction is improved, but total track length becomes too long for compact design
Solution Approach 1:
The patent uses aspheric surfaces with inflection points on the third lens element, which provide enhanced aberration correction capability. The specific focal length ratios (0.23<f3/f<0.35 and 0.40<f1/f<0.70) and the presence of inflection points on aspheric surfaces allow three elements to achieve correction levels previously requiring more elements, while maintaining compact total track length
Solution Approach 2:
The patent employs aspheric surfaces instead of spherical surfaces, particularly on the third lens element where inflection points are present. This curvature variation enables more efficient space utilization and better aberration control within a compact form factor, allowing three elements to perform the work of what would traditionally require more elements
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 reduces the total track length, enhances image quality, and improves photosensitivity by positioning the exit pupil far from the image plane, effectively correcting aberrations and maintaining a compact size suitable for portable electronics.
Implementation Method 1
a first lens element with positive refractive power having a convex object-side surface; a second lens element with positive refractive power having a convex image-side surface; a third lens element with positive refractive power having a convex object-side surface and a concave image-side surface, the object-side and image-side surfaces thereof being aspheric
Data Source
AI summary
This invention provides a photographing optical lens system in order from an object side to an image side including: a first lens element with positive refractive power having a convex object-side surface, a second lens element with positive refractive power having a convex image-side surface, a third lens element with positive refractive power having a convex object-side surface and a concave image-side surface, both the two surfaces being aspheric and at least one of them having at least one inflection point formed thereon; wherein the photographing optical lens system further comprises an aperture stop configured between an imaged-object and the second lens element, and there are three lens elements with refractive power.