Fixed Focus Lens System with High Abbe Number Lenses
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Fixed focus lenses used in surveillance cameras face challenges in correcting optical aberrations and maintaining focus across varying wavelengths from visible to infrared light, leading to reduced image quality and difficulty in monitoring large areas both day and night.
Innovation Solution
A fixed focus lens system comprising a first lens group with negative refractive power and a second lens group with positive refractive power, where the second lens group includes lenses with an Abbe's number of 80 or greater, along with specific focal length and Abbe's number ratios, to minimize focus distortion across different wavelengths, and an optional day-and-night filter unit for adaptive luminance control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If a wide-angle, large-aperture lens is used to monitor dark space over a wide area, then the surveillance coverage area is improved, but optical aberrations of peripheral portions worsen
Solution Approach 1:
The lens system is divided into multiple lens groups (first lens group with negative refractive power and second lens group with positive refractive power), where each group contains multiple lenses with specific Abbe's numbers. This segmentation allows different parts of the lens system to correct different types of optical aberrations, enabling effective correction of peripheral portion aberrations while maintaining wide-angle coverage.
Solution Approach 2:
The patent uses composite lens structures with lenses having different Abbe's numbers (specifically including lenses with Abbe's number of 80 or greater). By combining materials with different optical properties, the system achieves superior correction of optical aberrations across the wide field of view while maintaining the required aperture and angle characteristics.
2Measurement precision
If a fixed focus lens is designed for visible light, then daytime imaging performance is improved, but focus changes occur when wavelength varies to infrared rays at night
Solution Approach 1:
The patent selects specific Abbe's number parameters for the lens materials (lenses with Abbe's number of 80 or greater) to minimize focus distortion across different wavelengths. By carefully controlling the dispersion characteristics of the lens materials, the system maintains stable focus for both visible light during the day and infrared light at night, reducing the need for focus adjustment when wavelength changes.
3Adaptability or versatility
If lenses with high Abbe's number are used to reduce focus distortion, then focus stability across wavelengths is improved, but device complexity increases
Solution Approach 1:
The patent applies the high Abbe's number lens material strategy selectively to specific lenses within the lens groups rather than uniformly to all lenses. The second lens group includes two lenses with Abbe's number of 80 or greater, which is sufficient to achieve the desired focus stability while avoiding unnecessary complexity in the entire lens system. This localized application of high-performance materials optimizes the balance between performance and complexity.
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 lens system effectively reduces focus distortion and maintains high image resolution and luminance across varying wavelengths, enabling effective surveillance capabilities both day and night with minimal defocus and aberrations.
Implementation Method 1
a first lens group having a negative refractive power; and a second lens group having a positive refractive power... to minimize focus distortion across different wavelengths
Implementation Method 2
the second lens group includes two lenses having an Abbe's number of 80 or greater... An Abbe's number v3 of the third lens and an Abbe's number v4 of the fourth lens may satisfy the following condition: 0.25≤v3/v4
Data Source
AI summary
A fixed focus lens system includes a first lens group having a negative refractive power; and a second lens group having a positive refractive power, wherein the first lens group and the second lens group are sequentially arranged from an object side to an image side, and the second lens group includes two lenses having an Abbe's number of 80 or greater.