Five-Lens Imaging System Aberration Correction
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Solution Overview
Problem
Conventional imaging lenses with four elements are insufficient for larger image pickup devices with high resolving power, as they fail to correct curvature and chromatic aberration effectively, and plastic lenses like polycarbonate are unsuitable due to double refraction issues.
Innovation Solution
A five-lens configuration comprising a negative meniscus first lens, a positive second lens, a diaphragm, a positive third lens, a positive fourth lens, and a concave-convex fifth lens, with aspherical surfaces, optimized to correct aberrations and accommodate larger image pickup devices and high pixel counts, using materials like ZEONEX to minimize double refraction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the number of lens elements is increased from three to four to meet higher resolving power demands, then the resolving power is improved, but the correction of curvature of image and chromatic difference of magnification becomes insufficient for image pickup devices 1/2 inch or larger
Solution Approach 1:
The imaging lens is divided into five distinct lens elements (first through fifth lenses) with specific configurations. Each lens element serves particular functions: the first and second lenses form a negative-positive combination for chromatic aberration correction, while the third, fourth, and fifth lenses work together to correct curvature of image and other aberrations. This segmentation into five specialized elements provides sufficient correction capability for large image pickup devices while maintaining high resolving power.
Solution Approach 2:
Different lens elements are assigned specific optical properties and positions to address different aberration types locally. The first lens has negative refractive power with a meniscus shape for specific aberration control, the second lens has positive refractive power, the third lens has a convex face directed to the image, the fourth lens has positive refractive power near the optical axis, and the fifth lens has a concave face directed to the image near the optical axis. This local optimization of each element's properties enables comprehensive aberration correction across the entire image field.
2Ease of manufacture
If polycarbonate plastic lenses are used to simplify manufacturing, then manufacturing ease is improved, but double refraction occurs during molding requiring restricted lens thickness which decreases design freedom
Solution Approach 1:
The patent specifies precise thickness parameters and curvature radius parameters for each lens element to control double refraction effects in plastic lenses. By carefully controlling the thickness of each lens element and optimizing the curvature radii of their surfaces, the design minimizes double refraction during molding while maintaining adequate design freedom for achieving the required optical performance.
Solution Approach 2:
The imaging lens employs a composite structure combining multiple lens elements with different materials and properties. This includes using plastic lenses (such as ZEONEX or other amorphous resins with low double refraction characteristics) in combination with carefully designed glass or plastic elements. The composite arrangement allows each material to be used in its optimal form while collectively achieving the required optical performance without excessive double refraction.
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 five-lens configuration provides enhanced aberration correction, achieving high-performance imaging with reduced irregularity in light quantity across the image forming plane, suitable for larger image pickup devices and high pixel counts.
Implementation Method 1
a first lens having a negative meniscus shape with a convex face directed to the object side thereof; a second lens having a positive shape with a convex face directed to the object side thereof
Data Source
AI summary
An imaging lens comprises, in order arranged from an object side: a first lens of a negative meniscus lens which is curved to be convex towards an object; a second lens of a positive lens which is curbed to be convex on an object side surface thereof; a diaphragm; a third lens which is curved to be convex towards an image; a fourth lens having a positive refractive power in the vicinity of an optical axis; and a fifth lens which is curved to be concave towards the image in the vicinity of the optical axis while being curved to convex towards the image along a circumferential edge portion on an image side surface thereof.