Imaging Lens System Temperature Compensation
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Solution Overview
Problem
Surveillance cameras used in autonomous vehicles face challenges in maintaining high-resolution optical performance across varying temperature conditions, from -40 to 80°C, due to significant resolution changes with temperature fluctuations.
Innovation Solution
An imaging lens system comprising multiple lenses with specific refractive indices and Abbe numbers, arranged to satisfy certain conditional expressions, and made from different materials to maintain consistent optical performance across temperature changes, including a third lens with a refractive index temperature coefficient of 2.2 to 3.5 × 10^(-6/°C and a composite focal length ratio of 0<f34*0.8<f, where f is the focal length of the imaging lens system and f34 is the composite focal length of the third and fourth lenses.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a surveillance camera is designed for high resolution, then image quality is improved, but optical performance becomes sensitive to temperature changes
Solution Approach 1:
The patent applies parameter changes by carefully selecting lens materials with specific refractive indices and Abbe numbers, and by controlling the refractive index temperature coefficients within specific ranges. The conditional expressions (1) through (7) define precise parameter ranges for lens focal lengths, refractive indices, and Abbe numbers that compensate for temperature-induced optical performance variations while maintaining high resolution imaging capability
Solution Approach 2:
The patent employs composite materials by combining multiple lens elements made from different glass materials with distinct optical properties. Each lens (L1-L7) uses materials with specific refractive indices (Nd) and Abbe numbers (νd) that are strategically selected to balance each other's temperature sensitivity, creating a composite optical system that maintains stable performance across temperature extremes from -40°C to 80°C
2Measurement precision
If lens materials are selected for high resolution, then image quality is improved, but focal length changes significantly with temperature
Solution Approach 1:
The patent controls focal length stability by imposing specific constraints on the refractive index temperature coefficients of individual lenses. The conditional expressions require that the third lens has a refractive index temperature coefficient of 2.2 to 3.5×10^-6/°C, and the fourth lens has -110 to -80×10^-6/°C, creating a compensation mechanism that maintains constant focal length across temperature variations while preserving high resolution
3Device complexity
If a simple lens structure is used, then device complexity is reduced, but temperature compensation capability is insufficient
Solution Approach 1:
The patent divides the imaging lens into seven separate lens elements (L1-L7) with distinct optical functions and material properties. This segmentation allows each lens to be optimized for specific temperature compensation tasks, with positive and negative power lenses strategically arranged to counterbalance each other's thermal expansion and refractive index changes, achieving superior temperature adaptability without excessive complexity
Solution Approach 2:
The patent applies local quality by assigning different material properties to different lens elements based on their positions and functions within the optical system. Each lens has specifically tailored refractive indices, Abbe numbers, and temperature coefficients that are optimized for its local role in the overall temperature compensation mechanism, rather than using a uniform material throughout
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 imaging lens system ensures constant optical characteristics and focal length stability across extreme temperature conditions, enhancing the performance of surveillance cameras in autonomous vehicles.
Implementation Method 1
a third lens having a convex object-side surface; a fourth lens having positive refractive power
Implementation Method 2
The third lens has a refractive index temperature coefficient of 2.2 to 3.5×10^-6/°C
Data Source
AI summary
An imaging lens system includes: a first lens, a second lens, a third lens, a fourth lens, a fifth lens, a sixth lens, and a seventh lens, sequentially disposed from an object side. The third lens has a refractive index temperature coefficient of 2.2 to 3.5 [10−6/° C.], and 0<f34*0.8<f, where f is a focal length of the imaging lens system and f34 is a composite focal length of the third lens and the fourth lens.