Five-Lens Imaging Optics for Peripheral Light and Thermal Stability
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Solution Overview
Problem
Small surveillance cameras face a reduction in incident light at the peripheral portion of the optical axis due to the use of glass material lenses, which limits the angle of incident light required by the image sensor, leading to low resolution and significant resolution changes with temperature variations.
Innovation Solution
An imaging lens system comprising a first lens with negative refractive power and concave object-side surface, a second lens with positive refractive power and convex object-side surface, a third lens with positive refractive power and convex object-side surface, a fourth lens with negative refractive power and concave object-side surface, and a fifth lens with negative refractive power and convex object-side surface, made of specific materials and satisfying certain conditional expressions for focal lengths and radii of curvature.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If a glass material lens is used, then temperature stability and resolution consistency are improved, but the angle of incident light is limited causing light reduction at peripheral portions
Solution Approach 1:
The lens is divided into multiple segments with different materials: a first lens and second lens made of glass material for temperature stability, and a third lens made of plastic material to increase the angle of incident light. This segmentation allows each part to contribute different properties to resolve the contradiction between temperature stability and light transmission angle.
Solution Approach 2:
The lens system uses a composite structure combining glass material (for thermal stability and resolution consistency) and plastic material (for wider incident light angle). The third lens made of plastic material specifically addresses the light reduction issue at peripheral portions while the glass lenses maintain temperature stability.
2Illumination intensity
If the angle of incident light is increased, then light transmission at peripheral portions is improved, but temperature-induced resolution changes increase
Solution Approach 1:
The lens system is segmented into temperature-stable glass lenses (first and second lenses) and a plastic lens (third lens) that provides wider incident light angle. This segmentation allows the plastic lens to increase light transmission while glass lenses compensate for temperature-induced resolution changes.
Solution Approach 2:
The patent applies parameter changes by selecting specific refractive indices and Abbe numbers for different lens materials. The plastic third lens has parameters optimized for wide incident light angle, while glass lenses have parameters optimized for temperature stability, resolving the contradiction through parameter optimization.
3Manufacturing precision
If glass material lenses are used, then manufacturing precision and resolution are improved, but device complexity and cost increase
Solution Approach 1:
The lens system is segmented into three lenses with different materials: two glass lenses for high precision requirements and one plastic lens for cost-effective light transmission. This segmentation achieves high manufacturing precision where needed while reducing overall device complexity and cost through the use of plastic material in the third lens.
Solution Approach 2:
The composite lens system combines glass and plastic materials to balance manufacturing precision and device complexity. Glass lenses provide high precision for critical positions, while the plastic third lens reduces overall system complexity and cost while maintaining adequate precision through proper parameter selection.
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 enhances light transmission and maintains consistent resolution across temperature variations, minimizing light reduction at the peripheral portion of the optical axis and improving image quality.
Implementation Method 1
a first lens 110, a second lens 120, a third lens 130, a fourth lens 140, and a fifth lens 150 which are sequentially disposed in ascending numerical order along an optical axis of the imaging lens system 100... the second lens 120 has a positive refractive power... the fifth lens 150 is made of a plastic material
Data Source
AI summary
An imaging lens system includes a first lens, a second lens, a third lens, a fourth lens, and a fifth lens sequentially disposed in ascending numerical order along an optical axis of the imaging lens system from an object side of the imaging lens system toward an imaging plane of the imaging lens system, wherein the second lens has a positive refractive power and is made of a glass material, the fifth lens is made of a plastic material, and the imaging lens system satisfies the conditional expression f-number<2.10, where f-number is an f-number of the imaging lens system.