Nine-Lens Optical Imaging With Low F-Number Aberration Control
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Solution Overview
Problem
Optical systems in mobile devices face challenges in achieving bright images while minimizing aberrations and maintaining a compact form factor, as reducing the F value to enhance brightness often leads to increased aberrations.
Innovation Solution
An optical imaging system comprising nine lenses, including specific refractive indices, surface configurations, and conditional expressions to achieve a low F value (1.0 < F-number < 1.4) and compact size, with lenses made of plastic material and aspherical surfaces to minimize aberrations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If the entrance pupil size is increased to lower the F value and enhance image brightness, then image brightness is improved, but optical aberrations increase
Solution Approach 1:
The optical system is divided into nine lenses with different refractive powers and configurations. The first lens has positive refractive power, the second lens has negative refractive power, the third lens has positive refractive power, the fourth lens has positive refractive power, the fifth lens has positive refractive power, the sixth lens has negative refractive power, the seventh lens has positive refractive power, the eighth lens has positive refractive power, and the ninth lens has negative refractive power. This segmentation allows each lens to contribute to correcting specific aberrations while maintaining overall brightness.
Solution Approach 2:
Different lenses are assigned different refractive indices and surface curvatures tailored to their specific positions and functions. For example, the second lens has a refractive index of 1.60 or more and negative refractive power to correct chromatic aberration, while the fourth lens has positive refractive power and specific surface curvature to control spherical aberration. This local optimization of optical properties reduces overall aberrations while maintaining brightness.
2Illumination intensity
If the F value is reduced to achieve brighter images, then image brightness is improved, but the system complexity increases to control aberrations
Solution Approach 1:
The system uses nine lenses arranged in a specific sequence with alternating positive and negative refractive powers. This segmentation into multiple functional elements allows the system to achieve low F value while managing complexity through modular design, where each lens segment handles specific optical corrections.
Solution Approach 2:
The patent specifies precise parameter ranges for each lens including refractive indices (e.g., second lens: 1.60 or more, fourth lens: 1.50-1.60), surface curvatures, thicknesses, and spacing distances. By optimizing these parameters within defined ranges, the system achieves the desired brightness and aberration control without excessive complexity.
3Volume of moving object
If the optical system is made compact for mobile devices, then device size is reduced, but achieving both bright images and low aberrations becomes more difficult
Solution Approach 1:
The nine lenses are arranged in a compact nested configuration where each lens is positioned close to the others along the optical axis. The total length is controlled to be 8.95-9.05mm, with each lens contributing a small portion of the total length. This nested arrangement achieves compact size while maintaining optical performance through careful design of each lens segment.
Solution Approach 2:
The patent utilizes aspherical surfaces and inflection points on lens surfaces to control aberrations in the optical path. The seventh and eighth lenses include inflection points on their surfaces, and the eighth lens has a convex image-side surface. This dimensional complexity in surface geometry allows compact system size while controlling aberrations that would otherwise require larger apertures.
4Object-affected harmful factors
If multiple lenses with specific refractive indices are used to reduce aberrations, then optical performance is improved, but manufacturing complexity increases
Solution Approach 1:
The patent specifies refractive index ranges for each lens material (e.g., second lens: 1.60 or more, fourth lens: 1.50-1.60, sixth lens: 1.60 or more). By defining acceptable parameter ranges rather than requiring exact values, the patent facilitates manufacturing while maintaining optical performance. These ranges allow for standard glass or plastic materials that are easier to produce.
Solution Approach 2:
The optical system uses a composite lens structure combining different materials with specific refractive indices. The lenses are made of plastic material with carefully selected refractive properties. This composite approach allows optimization of each lens segment's optical characteristics while using materials that are relatively easy to manufacture compared to exotic glass combinations.
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 system achieves bright images with reduced aberrations and a slim thickness, meeting the requirements for miniaturization and brightness while maintaining optical performance.
Implementation Method 1
an optical imaging system includes a first lens, a second lens, a third lens, a fourth lens having positive refractive power, a fifth lens, a sixth lens, a seventh lens having positive refractive power, an eighth lens, and a ninth lens
Data Source
AI summary
An optical imaging system is provided. The optical imaging system includes a first lens, a second lens, a third lens, a fourth lens having positive refractive power, a fifth lens, a sixth lens, a seventh lens having positive refractive power, an eighth lens and a ninth lens, wherein the first lens to the ninth lens are disposed in order from an object side, and wherein conditional expressions 1.0<F-number<1.4 and 1.30≤TTL/f<1.40 are satisfied, where TTL is a distance from an object-side surface of the first lens to an image plane on an optical axis, and f is a focal length of the optical imaging system.