Imaging Lens System With Refractive-Index Temperature Compensation
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Solution Overview
Problem
Small-sized surveillance cameras experience significant resolution changes due to temperature fluctuations, necessitating a lens system that maintains constant optical performance across varying ambient temperatures.
Innovation Solution
An imaging lens system comprising specific lenses with high refractive indices and controlled refractive index temperature coefficients, along with a stop and focus correction lenses, to stabilize optical performance from −40°C to 80°C.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If conventional lenses are used in small-sized surveillance cameras, then the camera can be compact, but the resolution changes greatly according to temperature changes
Solution Approach 1:
The patent applies parameter changes by selecting lens materials with specific refractive indices (1.7 or greater) and refractive index temperature coefficients (lower than 0) that compensate for thermal expansion effects. This allows the optical system to maintain consistent focal length and imaging properties across temperature ranges from -40°C to 80°C, resolving the contradiction between compact size and temperature-stable resolution
Solution Approach 2:
The patent uses composite material principles by combining multiple lens elements with different refractive index temperature coefficients. Specifically, it employs at least one lens with a negative temperature coefficient to counterbalance the positive thermal expansion of other components, creating a composite optical system that maintains stable resolution despite temperature variations in a compact form factor
2Volume of moving object
If lenses with high refractive index and positive temperature coefficient are used, then the lens can be compact, but the optical performance becomes unstable under temperature changes
Solution Approach 1:
The patent applies the counterweight principle by introducing at least one lens element with a negative refractive index temperature coefficient that optically counterbalances the positive thermal effects of other lens elements. This creates an internal compensation mechanism where the negative coefficient lens acts as an optical 'counterweight' to thermal expansion, maintaining stable optical performance in a compact lens design
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 maintains consistent imaging quality across extreme temperature ranges, ensuring high resolution and optical stability for surveillance applications.
Implementation Method 1
an imaging lens system includes a first lens, a second lens, a third lens having negative refractive power, a fourth lens, a fifth lens, and a sixth lens
Implementation Method 2
one or more of the first to sixth lenses has a refractive index of 1.8 or greater, and has a refractive index temperature coefficient (10−6/° C.) of 3 or greater
Data Source
AI summary
An imaging lens system includes a first lens, a second lens, a third lens having negative refractive power, a fourth lens, a fifth lens, and a sixth lens, disposed in order from an object side in a direction of an imaging plane, wherein one or more of the first to sixth lenses has a refractive index of 1.8 or greater, and has a refractive index temperature coefficient (10−6/° C.) of 3 or greater.