Aspheric Plastic Lens System for Infrared Imaging
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Solution Overview
Problem
Conventional imaging lens systems are limited by excessive spherical glass lenses, leading to reduced design flexibility and manufacturing complexity, and fail to effectively capture high-quality images in both visible light and infrared bands, especially in low-light conditions.
Innovation Solution
A compact optical lens system comprising four aspheric lens elements with specific refractive powers and surface shapes, including a convex first lens, a concave-convex second lens, a convex third lens, and a concave-convex fourth lens, optimized for reduced total track length and improved sensitivity, allowing for effective infrared imaging.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If spherical glass lenses are used to correct chromatic aberration, then image quality is improved, but the total track length increases and design flexibility is reduced
Solution Approach 1:
The patent changes the material parameter from glass to plastic and the surface geometry from spherical to aspheric. The aspheric surfaces allow for better aberration correction with fewer elements, reducing the total track length while maintaining image quality. The plastic material enables more flexible shaping and reduces the number of required lens elements.
Solution Approach 2:
The patent divides the optical system into four distinct lens elements with specific aspheric surface configurations. This segmentation allows each element to be optimized for specific functions (positive and negative refractive powers) while maintaining a compact overall structure that reduces total track length compared to conventional designs.
2Manufacturing precision
If multiple spherical glass lenses are adhered together to form doublets, then chromatic aberration is corrected, but manufacturing complexity increases
Solution Approach 1:
The patent changes the surface geometry parameter from spherical to aspheric and the material from glass to plastic. Aspheric plastic lenses can be manufactured more easily using injection molding techniques, eliminating the complex multi-step process of adhering multiple spherical glass lenses together. This single-element approach with aspheric surfaces provides both chromatic and spherical aberration correction without the manufacturing complexity of doublets.
3Illumination intensity
If conventional four-lens systems designed for visible light are used, then visible light imaging is achieved, but infrared detection capability is lost
Solution Approach 1:
The patent designs a universal optical lens system that functions across multiple spectral bands including visible light and infrared. The aspheric plastic lens elements are optimized to transmit both visible and infrared wavelengths effectively. The system can detect infrared radiation at night or in low-light conditions while maintaining visible light imaging capability, making it adaptable to various environmental conditions and application requirements.
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 achieves improved image quality, reduced aberrations, and enhanced sensitivity for both visible light and infrared applications, while maintaining a compact design suitable for portable electronic devices.
Implementation Method 1
a first lens element having a convex object-side surface; a second lens element with negative refractive power having a concave object-side surface and a convex image-side surface
Data Source
AI summary
This invention provides an optical lens system in order from an object side to an image side comprising: a first lens element having a convex object-side surface; a negative second lens element having a concave object-side surface and a convex image-side surface; a positive third lens element having a convex object-side surface and a convex image-side surface; a plastic negative fourth lens element having a concave object-side surface and a convex image-side surface, with both the object-side and image-side surfaces thereof being aspheric. By such arrangement, the incident angle of off-axis light projected onto the sensor can be suppressed for improving the sensitivity of the sensor effectively. Also, a sufficient back focal length can be retained for disposing other optical elements (e.g., an IR-pass filter), and thereby the system can be more suitable for the infrared aspect of optical imaging systems.