Image Pickup Lens Assembly Aberration Correction
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Solution Overview
Problem
Conventional miniaturized image pickup lens assemblies for camera mobile phones face challenges in reducing size while maintaining high resolution and correcting chromatic aberration and distortion, due to the complexity of spherical lens arrangements and gluing processes.
Innovation Solution
A four-lenses type assembly is designed with specific refractive power distributions and aspheric surfaces, including a first lens group with positive and negative lenses, a meniscus lens group, and an aperture stop between the first and second lenses, made from plastic using injection molding, to reduce system length and correct aberrations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional spherical lenses are used with multiple elements for chromatic aberration correction, then image quality is improved, but the optical system length increases and device miniaturization is hindered
Solution Approach 1:
The patent employs aspheric surfaces on multiple lens elements instead of conventional spherical surfaces. The aspheric profiles enable more effective control of light rays, providing both chromatic aberration correction and distortion correction while reducing the number of lens elements needed, thereby shortening the optical system length while maintaining or improving image quality.
Solution Approach 2:
The patent uses lenses with different refractive indices and Abbe numbers (e.g., positive lenses with high refractive power and negative lenses with specific Abbe numbers) arranged in a telephoto configuration. This composite lens design enables effective chromatic aberration correction through the interlaced positive and negative power elements, achieving high image quality with a compact structure.
2Manufacturing precision
If more spherical lenses are arranged to correct chromatic aberration and distortion, then aberration correction is improved, but the degree of freedom of the optical system is reduced and system length increases
Solution Approach 1:
The aspheric surfaces provide additional degrees of freedom for aberration correction without requiring more lens elements. The aspheric coefficients allow independent control of spherical aberration, coma, and other monochromatic aberrations, while the telephoto arrangement with interlaced positive and negative lenses addresses chromatic aberration, achieving comprehensive correction with a compact, low-complexity design.
3Ease of manufacture
If conventional gluing processes are used for assembling glass lenses, then assembly is achieved, but the gluing process is difficult to control and precision is reduced
Solution Approach 1:
The patent adopts plastic lens materials that can be molded with aspheric surfaces directly in the manufacturing process, eliminating the need for complex gluing assemblies. The injection molding process integrates lens formation and surface shaping in a single step, providing high precision and repeatability without the variability and control difficulties of conventional glass lens gluing processes.
4Manufacturing precision
If the aperture stop is positioned to achieve telecentric feature for improved photosensitivity, then photosensitivity is improved, but the optical system length increases
Solution Approach 1:
The aspheric lens surfaces enable the design of a telephoto optical system where the exit pupil is positioned far from the image plane, achieving the telecentric feature on the image side. This telecentric design ensures vertical light projection onto the photosensitive assembly, improving photosensitivity and reducing shading effects while maintaining a compact overall system length through the aspheric profile optimizations.
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 effectively reduces the optical system length, improves image quality, and enhances photosensitivity by controlling aberrations and distortion, while allowing for miniaturization and increased angle of view.
Implementation Method 1
a first lens with positive refractive power and a second lens with negative refractive power. The front surface of the first lens is convex.
Implementation Method 2
The rear surface of the second lens is concave. To effectively correct the chromatic aberration caused by the optical lens assembly, the Abbe number V2 of the second lens and the Abbe number V4 of the fourth lens satisfy the relations: V2<45, V4>55.
Implementation Method 3
The second lens group includes a meniscus third lens with positive refractive power, and the rear surface of the third lens is convex.
Implementation Method 4
The third lens group includes a fourth lens with a negative refractive power, and the front surface of the fourth lens is convex. the correction to the distortion and the chromatic aberration of magnification is very important
Implementation Method 5
The aperture stop is located between the first lens and the second lens of the first lens group for controlling the brightness of the optical system.
Data Source
AI summary
An image pickup lens assembly comprises three lens groups, from the object side to the image side: a first lens group, a second lens group, and a third lens group. The first lens group includes two lenses with refractive power, namely, a first lens with positive refractive power, and a second lens with negative refractive power. The front surface of the first lens is convex, and the rear surface of the second lens is concave. The second lens group includes a meniscus third lens with positive refractive power, the rear surface of the third lens is convex. The third lens group includes a fourth lens with negative refractive power, the front surface of the fourth lens is convex, and the rear surface of the fourth lens is aspheric. An aperture stop is located between the first lens and the second lens of the first lens group for controlling the brightness of the optical system.