Freeform Lens Module for Ultra-Wide-Angle Distortion Correction
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Solution Overview
Problem
Existing software lacks sufficient computing power to effectively correct optical distortion in dynamic videos captured by ultra-wide-angle lenses, which results in suboptimal image quality.
Innovation Solution
A lens module design incorporating multiple lenses with freeform surfaces and specific refractive powers, including a freeform fifth lens, to minimize distortion while ensuring high image quality across the field of view, with a configuration that includes a planar photosensitive chip and optimized curvature radii for each lens, facilitating miniaturization and distortion correction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of moving object
If a ultra-wide-angle lens is used to achieve a wider field of view, then the field of view is improved, but optical distortion increases
Solution Approach 1:
The lens system is divided into multiple lens elements (first lens, second lens, third lens, fourth lens, and fifth lens) with different refractive powers and surface characteristics. Each lens segment contributes to correcting specific distortion patterns, allowing the system to achieve wide field of view while minimizing overall optical distortion through coordinated segmentation of the optical path.
Solution Approach 2:
The fifth lens employs a freeform surface with non-uniform curvature distribution, where different regions of the lens surface have different refractive properties optimized for specific zones of the image field. This local quality variation allows precise control over distortion characteristics in different areas of the field of view, particularly correcting barrel distortion at the periphery while maintaining sharpness at the center.
2Object-affected harmful factors
If software processing is used to correct optical distortion, then distortion correction is achieved, but computing power requirements increase
Solution Approach 1:
The lens system performs distortion correction in advance during the optical imaging process itself, rather than requiring subsequent software processing. By incorporating freeform surfaces and specifically designed lens configurations that inherently minimize distortion, the correction action is completed at the optical stage, eliminating the need for computationally intensive post-processing software algorithms.
3Manufacturing precision
If multiple lenses with freeform surfaces are used to correct distortion, then image quality is improved, but device complexity increases
Solution Approach 1:
The lens system utilizes changes in surface geometry parameters, specifically employing freeform surfaces with controlled aspheric coefficients and curvature radii. By optimizing these geometric parameters across the multiple lens elements, the system achieves superior image quality and distortion correction. The parameter optimization balances the increased structural complexity with improved optical performance, creating a net benefit for the imaging system.
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 lens module achieves a distortion correction of 1.5% compared to 12.6% in comparative examples, significantly enhancing image quality, especially near the optical axis, and enabling effective processing of dynamic videos.
Implementation Method 1
a first lens, a second lens, a third lens, a fourth lens and a fifth lens... the fifth lens includes a freeform surface
Data Source
AI summary
A lens module includes a plurality of lenses arranged in sequence from an object side to an image side along an optical axis. At least one lens of the plurality of lenses is a freeform lens. An object-side surface and/or an image-side surface of the freeform lens is a freeform surface. An X-axis and a Y-axis are defined as two central axes perpendicular to each other on an image surface of the lens module. the freeform surface is described by the following sag equation:Z=Cxx2+Cyy21-(1+kx)Cx2x2-(1+ky)Cy2y2+∑ i=116αixi+∑ i=116βiyi+∑ i=1NAiZi(ρ,φ)Wherein,Cx=1Rx,Cy=1Ry, z is a sag of an optical surface; Rx and Ry are radius of curvature values in the x and y directions respectively; kx and ky are conic coefficients; αi, βi are polynomial coefficients; Ai is a polynomial coefficient, ρ is a radial coordinate, φ is an angular coordinate, and N is a number of terms. A terminal device also provided.