Optical Imaging Lens Assembly for Low-Light Telephoto Imaging
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Solution Overview
Problem
Current optical imaging lens assemblies face challenges in achieving high-resolution, long-distance imaging in low-light environments, particularly in slightly dark conditions, due to limitations in aperture size and telephoto characteristics.
Innovation Solution
The optical imaging lens assembly comprises seven lenses with specific refractive powers and surface types, optimized to balance aberrations and improve imaging quality, featuring a large aperture and telephoto characteristics through careful design of entrance pupil diameter, focal lengths, curvature radii, and spacing distances, ensuring high imaging quality and low sensitivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If the aperture of the optical imaging lens assembly is increased to improve low-light imaging performance, then the light gathering capability is enhanced, but the lens complexity and manufacturing difficulty increase
Solution Approach 1:
The optical imaging lens assembly is divided into seven independent lens elements with alternating positive and negative refractive powers. Each lens element can be independently designed, manufactured, and adjusted, allowing the system to achieve a large aperture (F/1.5 or larger) while maintaining manageable complexity through modular construction
Solution Approach 2:
Different lens elements are assigned specific local functions: the first lens element with positive refractive power provides strong light gathering capability for low-light performance, while subsequent elements with negative and alternating positive refractive powers correct specific aberrations in their respective zones, enabling the large aperture design to maintain imaging quality
2Measurement precision
If the telephoto characteristic is set to achieve long-distance high-resolution imaging, then the focal length is increased, but the lens assembly length and complexity increase
Solution Approach 1:
The lens assembly employs a telephoto configuration where the seventh lens element with negative refractive power positioned near the image plane effectively extends the focal length without proportionally increasing the physical length. This dynamic optical design achieves long-distance high-resolution imaging capability while keeping the overall assembly length compact
Solution Approach 2:
The seven lens elements are arranged in a nested sequence along the optical axis with alternating positive and negative refractive powers. This nested configuration allows the optical path to fold back on itself, achieving a telephoto effect where the effective focal length is longer than the physical length of the lens assembly
3Measurement precision
If multiple lens elements with alternating refractive powers are used to improve imaging quality, then aberration correction is enhanced, but the manufacturing precision requirements increase
Solution Approach 1:
The patent specifies precise parameter ranges for each lens element including refractive power, curvature radii, and thickness ratios. By controlling these parameters within defined ranges (e.g., the ratio of curvature radii R3/R4 between 0.6-1.2, and spacing ratios T34/T45 between 0.8-1.5), the design achieves aberration correction while maintaining manufacturability through standardized tolerance specifications
4Illumination intensity
If the entrance pupil diameter and focal length are optimized for large aperture and telephoto characteristics, then low-light and long-distance imaging are improved, but distortion and aberrations increase
Solution Approach 1:
The design intentionally uses the seventh lens element with negative refractive power to counteract the inherent distortions and aberrations generated by the large aperture first lens element. The negative power element acts as a corrective element that converts the harmful effects of the large aperture into beneficial imaging performance, achieving both low-light capability and low distortion simultaneously
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 high-quality imaging in low-light conditions by optimizing the refractive powers and surface types of the lenses, achieving a large aperture and telephoto characteristics, thereby enhancing the lens assembly's performance in capturing images with reduced distortion and aberrations.
Implementation Method 1
a first lens with a positive refractive power
Implementation Method 2
a second lens with a negative refractive power
Implementation Method 3
a sixth lens with a positive refractive power
Implementation Method 4
a seventh lens with a negative refractive power
Data Source
AI summary
An optical imaging lens assembly sequentially includes, from an object side to an image side along an optical axis, a first lens (E1) with a positive refractive power, a second lens (E2) with a negative refractive power, a third lens (E3) with a refractive power, a fourth lens (E4) with a refractive power, a fifth lens (E5) with a refractive power, a sixth lens (E6) with a positive refractive power, and a seventh lens (E7) with a negative refractive power. EPD is an entrance pupil diameter of the optical imaging lens assembly, Semi-FOV is a half of a maximum field of view of the optical imaging lens assembly, and EPD and Semi-FOV satisfy: 11 mm<EPD/TAN(Semi-FOV)<20 mm. Therefore, a good shooting effect is achieved in a slightly dark environment.