Five-Lens Imaging Lens Design for Wide-Angle Aberration Correction
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Solution Overview
Problem
Existing imaging lenses for compact mobile devices face challenges in achieving high resolution, compactness, low-profile design, and a wide angle of view while effectively correcting aberrations, as they often compromise on one or more of these factors due to difficulties in optical design and material costs.
Innovation Solution
A compact and low-profile imaging lens design featuring a specific arrangement of five lenses with aspheric surfaces and varying refractive powers, including a double-sided aspheric first lens, a biconvex second lens, a meniscus third lens, a positive fourth lens, and a meniscus fifth lens, optimized by conditional expressions to achieve a wide angle of view and improved aberration correction, using plastic materials to reduce production costs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of moving object
If the photographing angle of view is widened, then the angle of view increases, but aberration correction becomes very difficult and optical performance deteriorates
Solution Approach 1:
The imaging lens is divided into five distinct lens elements (first lens L1, second lens L2, third lens L3, fourth lens L4, and fifth lens L5) with different refractive powers and surface configurations. This segmentation allows each element to contribute differently to the overall optical performance, enabling wide-angle coverage while distributing the burden of aberration correction across multiple elements rather than relying on a single complex element.
Solution Approach 2:
The patent employs asymmetric surface designs including double-sided aspheric surfaces on the first lens, meniscus shapes on the third and fifth lenses, and varying curvature radii across different surfaces. These asymmetric configurations are strategically designed to correct off-axis aberrations that are particularly problematic in wide-angle applications, such as coma and astigmatism, while maintaining the wide field of view.
2Ease of manufacture
If all lens surfaces are spherical, then manufacturing is simpler, but spherical aberrations are significant and imaging performance is poor
Solution Approach 1:
The patent introduces aspheric surfaces on the first lens (both object-side and image-side surfaces) and on the fifth lens (image-side surface). These aspheric surfaces are defined by specific curvature radius ratios (e.g., |r1/r2| between 0.7-1.3) and include higher-order aspheric terms to precisely control spherical aberration and other monochromatic aberrations, achieving superior imaging performance compared to purely spherical surfaces.
3Manufacturing precision
If glass material is used for all lenses, then optical performance is good, but production cost is high
Solution Approach 1:
The patent specifies precise refractive index ranges for each lens element (e.g., first lens: 1.45-1.70, second lens: 1.40-1.75, third lens: 1.50-1.80) and defines the relationship between refractive indices of adjacent elements (e.g., Nd1 < Nd2, Nd3 < Nd4). These parameter specifications enable the use of plastic materials with appropriate optical properties, reducing production cost while maintaining the ability to correct chromatic and spherical aberrations through controlled refractive index variations.
4Length of moving object
If the total track length is reduced for compactness, then the device becomes more compact, but aberration correction becomes more difficult
Solution Approach 1:
The patent creates a compact telephoto-type lens structure where the fifth lens (negative meniscus) is positioned close to the image plane, and the four positive-power lenses (L1, L2, L4 and the positive component of L3) are arranged in a nested-like configuration toward the object side. This nesting achieves a short total track length (TTL) while maintaining sufficient optical path length for effective aberration correction through the coordinated action of all five elements.
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 design provides a wide angle of view of up to 90 degrees, high brightness with an F-value of 2.2 to 2.4, and effective correction of various aberrations, while maintaining a short total track length and low-profile form factor, suitable for integration in compact mobile devices.
Implementation Method 1
a first lens as a double-sided aspheric lens with positive or negative refractive power
Implementation Method 2
both surfaces of which are aspheric and has an object-side surface with an aspheric shape which changes from convex in the vicinity of an optical axis to concave in a peripheral portion
Data Source
AI summary
A low-cost, compact and low-profile imaging lens with relatively high brightness, which provides a wide angle of view of about 90 degrees and corrects various aberrations properly. It is designed for use in a solid-state image sensor and includes the following elements arranged in order from an object side to an image side: a first lens as a positive or negative double-sided aspheric lens having a convex object-side surface near an optical axis; an aperture stop; a positive second lens having a convex image-side surface; a negative third lens having a concave image-side surface; a positive fourth lens having a convex image-side surface; and a fifth lens as a negative meniscus lens having a concave image-side surface near the optical axis. It satisfies a conditional expression (1) below: 0.9<ih/f<1.1 (1) where f: focal length of the overall optical system of the imaging lens ih: maximum image height.