Five-Element Image Lens Assembly for Infrared Image Quality
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Solution Overview
Problem
Conventional optical systems struggle to balance high image quality, low sensitivity, proper aperture size, miniaturization, and field of view requirements for infrared image capture in electronic devices like robot vacuums, especially in applications requiring object distance recognition.
Innovation Solution
An image lens assembly comprising five lens elements with specific optical configurations, including concave and convex surfaces, inflection points, and material choices to optimize f-number, focal lengths, and Abbe numbers, enhancing field of view and image quality while reducing sensitivity and manufacturing costs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a conventional optical system is used for infrared image capture, then the structure is simple, but it cannot achieve high image quality, low sensitivity, proper aperture size, miniaturization and desirable field of view simultaneously
Solution Approach 1:
The optical system is divided into five distinct lens elements with specific configurations (first lens element with negative refractive power, second through fifth lens elements with positive refractive power). Each lens element has specifically designed surface curvatures and thicknesses to address different optical requirements, allowing the system to achieve high image quality while managing complexity through functional segmentation
Solution Approach 2:
Different regions of the lens elements have different optical properties. The outer-side and inner-side surfaces of each lens element have specifically designed curvature radii (e.g., R1, R2 for the first lens element). The inflection point on the outer-side surface of the first lens element creates local variations in refractive power to correct aberrations and improve image quality in different field regions
2Manufacturing precision
If the aperture size is increased to improve light gathering, then the image quality improves, but the sensitivity increases and miniaturization is compromised
Solution Approach 1:
The system optimizes the f-number parameter to a specific range (0.40 < Fno ≤ 2.20) that balances aperture size, light gathering capability, and sensitivity. The focal length ratios are carefully controlled (e.g., 1.20 < |f/f1|/(|f/f2|+|f/f4|) ≤ 5.00) to maintain proper image quality while managing the aperture's impact on sensitivity and overall system size
3Area of stationary object
If the field of view is expanded to capture more scene, then the coverage improves, but the image quality and focal length control become more difficult
Solution Approach 1:
The lens elements feature asymmetric surface curvatures with inflection points (e.g., the outer-side surface of the first lens element has an inflection point). This asymmetric design allows the system to expand the field of view while maintaining image quality across different field regions by locally adjusting the light path in different areas of the lens
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 achieves improved image quality, increased field of view, and reduced sensitivity, while maintaining a balanced aperture size and miniaturization, suitable for infrared image capture in various electronic devices.
Implementation Method 1
The first lens element has negative refractive power, the outer-side surface of the first lens element is concave in a paraxial region thereof
Data Source
AI summary
An image lens assembly includes five lens elements which are, in order from an outer side to an inner side along an optical path: a first lens element, a second lens element, a third lens element, a fourth lens element and a fifth lens element. Each of the five lens elements has an outer-side surface facing toward the outer side and an inner-side surface facing toward the inner side. The outer-side surface of the first lens element is concave in a paraxial region thereof, and the outer-side surface of the first lens element has at least one inflection point.