Six-Lens Imaging Optical Assembly with Doublet Rear Group
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Solution Overview
Problem
Conventional imaging lens assemblies with a large angle of view suffer from ineffective aberration correction and have a long total track length, which limits their ability to provide high image quality and a wide field of view simultaneously.
Innovation Solution
The proposed imaging optical lens assembly consists of a front lens group with a specific arrangement of six lens elements, including a negative and positive refractive power doublet, and a rear lens group with a positive and negative refractive power doublet, optimized by specific curvature and distance relations to enhance field of view and correct aberrations, thereby reducing the total track length.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of moving object
If a conventional imaging lens assembly uses an inverse telephoto structure with one lens element in the rear lens group to achieve a wide field of view, then the field of view is enlarged, but the aberration correction becomes ineffective
Solution Approach 1:
The lens assembly is divided into a front lens group and a rear lens group with distinct functions. The front lens group (first four elements) primarily handles field of view expansion, while the rear lens group (doublet structure) specializes in aberration correction. This segmentation allows each group to be optimized independently for its specific function.
Solution Approach 2:
The rear lens group employs a doublet structure where the fifth and sixth lens elements work together to simultaneously correct multiple types of aberrations (spherical, coma, astigmatism, field curvature) while maintaining the wide field of view capability. This multi-functional design resolves the contradiction by making the rear group responsible for both field of view maintenance and aberration correction.
2Device complexity
If a conventional imaging lens assembly uses a simple rear lens group structure to reduce complexity, then the device complexity is reduced, but the total track length becomes too long
Solution Approach 1:
The fifth and sixth lens elements are combined into a tight doublet structure with minimal air gap between them. This merging reduces the overall optical path length while maintaining the corrective functions of both positive and negative power elements, thus shortening the total track length without significantly increasing structural complexity.
Solution Approach 2:
The patent employs specific parameter relationships (curvature radii ratios, focal length ratios, spacing distances) to optimize the doublet structure. By carefully controlling parameters such as R4/R5, Rc/Rd, and the distances Dsa, SL, and TTL, the system achieves compact dimensions while maintaining optical performance.
3Manufacturing precision
If a conventional imaging lens assembly uses more lens elements to improve image quality, then the image resolution is improved, but the total track length increases
Solution Approach 1:
The patent assigns different local qualities to different lens elements based on their positions and functions. The front elements focus on field expansion with specific curvature characteristics, while the rear doublet elements have optimized refractive indices and curvature radii specifically for aberration correction. This localized optimization allows six elements to achieve high resolution in a compact form.
Solution Approach 2:
The lens system uses lens elements with different refractive indices and Abbe numbers (e.g., N5=1.508, ν5=64.2; N6=1.697, ν6=25.6) to correct chromatic and monochromatic aberrations simultaneously. This composite approach with diverse optical materials enables high image quality without requiring additional lens elements that would increase track length.
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 enlarges the field of view while achieving high image resolution and balancing aberration correction, making it suitable for compact electronic devices such as mobile phone cameras and rear-view cameras.
Implementation Method 1
a first lens element with negative refractive power having a convex object-side surface and a concave image-side surface; a second lens element with negative refractive power having a convex object-side surface and a concave image-side surface; a third lens element with positive refractive power having a convex object-side surface and a convex image-side surface; a fourth lens element with positive refractive power having a concave object-side surface and a convex image-side surface; a fifth lens element with positive refractive power having a convex object-side surface and a convex image-side surface; and a sixth lens element with negative refractive power having a concave object-side surface and a convex image-side surface
Data Source
AI summary
This invention provides an imaging optical lens assembly, in order from an object side to an image side comprising: a front lens group, an aperture stop and a rear lens group; wherein the front lens group comprises, in order from the object side to the image side: a first lens element with negative refractive power having a concave image-side surface; a second lens element with negative refractive power; a third lens element with positive refractive power and a fourth lens element with positive refractive power; wherein the rear lens group comprises, in order from the object side to the image side: a fifth lens element with positive refractive power; and a sixth lens element with negative refractive power; wherein the fifth lens element and the sixth lens element are connected to form a doublet. By such arrangement, sufficient field of view is provided, and the aberration of the lens assembly is corrected for obtaining high image resolution.