Imaging Lens Aberration Correction via Segmented Groups
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Solution Overview
Problem
Conventional imaging lenses for small cameras, such as smartphones and digital still cameras, face challenges in achieving both downsizing and satisfactory aberration correction, particularly in achieving high resolution while maintaining a short total track length and minimizing size.
Innovation Solution
The imaging lens configuration includes a first lens group with positive refractive power, a second lens group with negative refractive power, and a third lens group with negative refractive power, arranged from the object side to the image plane side, with specific Abbe's number and curvature radius conditions to correct chromatic aberration and field curvature, and includes aspheric surfaces to manage axial and off-axis chromatic aberrations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the number of lenses is increased to achieve high resolution, then the imaging quality is improved, but the total track length and size of the imaging lens increase
Solution Approach 1:
The imaging lens is divided into three lens groups (first lens group with positive refractive power, second lens group with negative refractive power, and third lens group with negative refractive power) arranged from the object side to the image plane side. This segmentation allows for effective aberration correction while maintaining a compact total track length, resolving the contradiction between achieving high resolution and keeping the lens size small.
2Reliability
If a seven-lens configuration is used to correct aberrations, then the aberration correction is improved, but the device complexity and size increase
Solution Approach 1:
The patent specifies particular parameter ranges for the seven lenses including focal lengths (f1, f2, f3, f4, f5, f6, f7), Abbe's numbers (νd1, νd2, νd3, νd4, νd5, νd6, νd7), and curvature radii (R1, R2, R3, R4, R5, R6, R7, R8, R9, R10, R11, R12, R13, R14, R15). By optimizing these parameters within specific ranges, the patent achieves effective aberration correction while maintaining a manageable device complexity and compact size.
3Length of stationary object
If the focal length ratio between first lens group and second lens group is adjusted for downsizing, then the total track length is reduced, but the aberration correction becomes insufficient
Solution Approach 1:
The patent establishes specific parameter ranges including 0.3 < f1/f < 0.6, -1.5 < f2/f1 < -0.5, and -3.0 < f4/f5 < -1.0, where f1 is the focal length of the first lens, f2 is the focal length of the second lens, f4 is the focal length of the fourth lens, and f5 is the focal length of the fifth lens. These parameter optimizations enable the patent to achieve both downsizing and satisfactory aberration correction simultaneously.
4Length of stationary object
If the back focal length is reduced for downsizing, then the imaging lens size is decreased, but the space for inserting filters and the correction of astigmatism and field curvature are compromised
Solution Approach 1:
The patent specifies that 0.05 < D34/f < 0.2, where D34 is the distance between the third lens and the fourth lens, and f is the focal length of the entire imaging lens. This parameter optimization enables the patent to maintain an appropriate back focal length for filter insertion while achieving effective correction of astigmatism and field curvature in a compact imaging 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
This configuration allows for a compact imaging lens with improved aberration correction, including chromatic aberration and field curvature, enabling high-resolution imaging while maintaining a small size suitable for portable devices and small cameras.
Implementation Method 1
an imaging lens includes a first lens group having positive refractive power, a second lens group having negative refractive power, and a third lens group having negative refractive power, arranged in the order from the object side to the image plane side
Implementation Method 2
includes aspheric surfaces to manage axial and off-axis chromatic aberrations
Data Source
AI summary
An imaging lens includes a first lens having positive refractive power; a second lens; a third lens; a fourth lens; a fifth lens; a sixth lens; and a seventh lens having negative refractive power, arranged in this order from an object side to an image plane side. The seventh lens is formed in a meniscus shape near an optical axis thereof. The fourth lens has a specific focal length.