Seven-Lens Imaging Assembly for Compact Large-Aperture Optical Systems
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Solution Overview
Problem
Conventional optical systems with large apertures face challenges in achieving both compact size and high image quality, particularly in maintaining peripheral image quality due to their long total track length and poor peripheral image quality.
Innovation Solution
An imaging lens assembly comprising seven lens elements with specific refractive powers and surface shapes, including aspheric surfaces and inflection points, is designed to optimize focal lengths, curvature radii, and axial distances to achieve a compact form while improving peripheral image quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If the aperture size is increased to improve low light imaging capability and depth of focus, then the imaging functionality is enhanced, but the total track length increases making the system large in size
Solution Approach 1:
The patent employs aspheric surfaces on multiple lens elements (first, fourth, fifth, and seventh lens elements) to replace traditional spherical surfaces. This curvature optimization enables better control of light paths, allowing the system to achieve large aperture (f/1.7 or larger) while maintaining a compact total track length of 1.30 times the focal length or less.
Solution Approach 2:
The patent optimizes specific parameter relationships including the ratio of total track length to sum of central thicknesses (Td/ΣCT ≤ 1.65) and the combined focal length ratio (1.10 ≤ |f/f6| + |f/f7| ≤ 4.00). These parameter changes enable the system to achieve both large aperture and compact size simultaneously.
2Illumination intensity
If the aperture size is increased to improve low light imaging capability, then the imaging functionality is enhanced, but the peripheral image quality deteriorates
Solution Approach 1:
The patent applies different surface characteristics to different regions of the lens elements. Specifically, aspheric surfaces are used on the first, fourth, fifth, and seventh lens elements, with the seventh lens element having a concave paraxial region and convex off-axis region. This local quality differentiation corrects peripheral aberrations while maintaining central image quality, enabling large aperture operation without sacrificing peripheral sharpness.
Solution Approach 2:
The use of aspheric surfaces with optimized curvature radii (R8 for fourth lens element image-side surface, R10 for fifth lens element image-side surface) enables precise control of light rays across the entire field of view. This curvature optimization corrects field curvature and distortion, maintaining high peripheral image quality even with large aperture.
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 the creation of a compact optical system with a large aperture that maintains high image quality across the entire image field, addressing the limitations of conventional systems by efficiently utilizing space and correcting aberrations.
Implementation Method 1
The first lens element with positive refractive power has an object-side surface being convex in a paraxial region thereof and an image-side surface being concave in a paraxial region thereof. An object-side surface and the image-side surface of the seventh lens element are both aspheric.
Implementation Method 2
The image-side surface of the seventh lens element has at least one convex shape in an off-axis region thereof. At least one of an image-side surface of the fourth lens element and an image-side surface of the fifth lens element has at least one inflection point.
Data Source
AI summary
An imaging lens assembly includes, in order from an object side to an image side: a first lens element, a second lens element, a third lens element, a fourth lens element, a fifth lens element, a sixth lens element and a seventh lens element. The first lens element with positive refractive power has an object-side surface being convex in a paraxial region thereof and an image-side surface being concave in a paraxial region thereof. The seventh lens element has an image-side surface being concave in a paraxial region thereof. The image-side surface of the seventh lens element has at least one convex shape in an off-axis region thereof. An object-side surface and the image-side surface of the seventh lens element are aspheric. At least one of an image-side surface of the fourth lens element and an image-side surface of the fifth lens element has at least one inflection point.