Four-Element Optical Lens Assembly with Aspheric Surfaces and Dual Stops
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional compact imaging lenses for portable electronic devices face challenges in achieving high image quality due to increased complexity and unwanted light reflections, which limit their resolution and compactness.
Innovation Solution
The optical photographing lens assembly consists of four elements with specific refractive powers and surface profiles, including a first lens with positive refractive power, a second with negative refractive power, a third with balanced refractive power, and a fourth with a concave image-side surface and inflection point, along with strategically placed stops to control light and reduce aberrations, thereby maintaining a moderate total track length and improving image quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If more lens elements are added to improve image quality and resolution, then the imaging performance is improved, but the total track length increases and compactness is reduced
Solution Approach 1:
The patent employs aspheric surfaces on multiple lens elements (first, third, and fourth lens elements) to correct optical aberrations more effectively than spherical surfaces. This allows achieving high image quality with a compact four-element design, resolving the contradiction between image quality and compactness by using curved surfaces that provide greater design freedom and aberration correction capability without adding more elements
Solution Approach 2:
The patent optimizes specific parameter relationships including the focal length ratio between positive and negative lens elements (|f3/f4| between 1.8-2.5), the Abbe number difference (V1-V2 between 25-45), and the position of inflection points on the fourth lens element. These parameter optimizations enable compact total track length while maintaining high image quality through precise control of optical characteristics
2Length of stationary object
If lens elements are arranged closer together to reduce total track length, then compactness is improved, but multiple reflections and refractions of unwanted light increase, compromising image quality
Solution Approach 1:
The patent strategically places stops (aperture stops) within the lens assembly to block and remove unwanted reflected and refracted light rays before they can reach the image plane. This extraction of harmful light paths allows compact arrangement of lens elements while maintaining image quality by preventing ghost images and flare from multiple reflections
Solution Approach 2:
The patent uses the negative refraction characteristics of the second and fourth lens elements with specific surface curvatures to redirect unwanted reflected light away from the image plane. The inflection points on the fourth lens element's image-side surface are specifically positioned to control and redirect light paths, converting potentially harmful multiple reflections into beneficial light control that maintains image quality in a compact design
3Measurement precision
If conventional spherical-surface glass lenses are used to correct chromatic aberration, then chromatic aberration is corrected, but the system freedom is curtailed and total track length cannot be reduced easily
Solution Approach 1:
The patent combines lens elements with different Abbe numbers (V1-V2 between 25-45) to achieve chromatic aberration correction through material dispersion differences. This composite approach using materials with varying optical properties enables effective chromatic correction while maintaining design freedom and compactness, avoiding the need for complex spherical glass lens assemblies
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 effectively reduces the total track length, corrects chromatic and astigmatism aberrations, and minimizes unnecessary light reflections, enhancing image quality and compactness for use in portable electronic products.
Implementation Method 1
a first lens element with positive refractive power having a convex object-side surface, at least one of the object-side and image-side surfaces thereof being aspheric; a second lens element with negative refractive power having a concave image-side surface
Implementation Method 2
the optical photographing lens assembly further comprises another stop disposed between the second and fourth lens elements
Implementation Method 3
a fourth lens element with negative refractive power having a concave image-side surface on which at least one inflection point is formed
Data Source
AI summary
This invention provides an optical photographing lens assembly comprising, in order from an object side to an image side: a first lens element with positive refractive power having a convex object-side surface, at least one of the object-side and image-side surfaces thereof being aspheric; a second lens element with negative refractive power having a concave image-side surface; a third lens element with positive refractive power having a concave object-side surface and a convex image-side surface; and a fourth lens element with negative refractive power having a concave image-side surface on which at least one inflection point is formed, the object-side and image-side surfaces thereof being aspheric; wherein a stop is disposed between an imaged object and the first lens element and an electronic sensor is disposed at an image plane for forming images of the imaged object; and wherein the optical photographing lens assembly further comprises another stop disposed between the second and fourth lens elements.