Four-Element Optical Imaging Lens with Cemented Interfaces
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Solution Overview
Problem
Developing an optical imaging lens with a long effective focal length while maintaining excellent imaging quality is a challenge, particularly in portable electronic devices where space and performance are critical.
Innovation Solution
The optical imaging lens design incorporates a sequence of lens elements with specific refracting powers and surface shapes, including convex and concave regions, and cemented surfaces to achieve a high EFL/Fno ratio, ensuring a long focal length and good imaging quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the effective focal length is increased to achieve higher optical zoom magnification, then the optical zoom capability is improved, but the lens structure becomes more complex and imaging quality may deteriorate
Solution Approach 1:
The lens is divided into four distinct lens elements, each with specific refractive powers and surface shape characteristics. This segmentation allows each element to contribute differently to the overall optical function, enabling long effective focal length while controlling complexity through modular design
Solution Approach 2:
Different regions of the lens elements have different surface shapes (convex optical axis regions, concave periphery regions) and refractive powers. This local quality variation allows precise control of light paths to achieve both long focal length and high imaging quality without requiring excessive structural complexity
2Length of moving object
If multiple lens elements are used to achieve long effective focal length, then the focal length is improved, but the number of surfaces requiring treatment and adjustment increases
Solution Approach 1:
Adjacent lens elements are cemented together at their interfaces (image-side surface of Nth element to object-side surface of N+1th element), merging multiple surfaces into single cemented interfaces. This reduces the total number of independent surfaces requiring separate treatment and adjustment while maintaining the long effective focal length through the four-element configuration
3Ease of manufacture
If the lens elements are cemented together to simplify assembly, then the ease of manufacture is improved, but the chromatic aberration correction may be affected
Solution Approach 1:
The cemented interfaces are designed with specific curvature parameters and refractive index combinations that simultaneously achieve mechanical bonding (simplifying assembly) and optical function (correcting chromatic aberration). The second lens element's positive refractive power and third lens element's negative refractive power, combined with cemented interfaces, create achromatic doublet effects that correct chromatic aberration while maintaining manufacturing simplicity
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 design effectively increases the effective focal length while maintaining high image quality and simplifying assembly by reducing the need for additional surface treatments and adjustments, enhancing the durability and chromatic aberration correction of the lens.
Implementation Method 1
Each of the first lens element to the fourth lens element includes an object-side surface facing the object side and allowing imaging rays to pass through, and an image-side surface facing the image side and allowing the imaging rays to pass through
Implementation Method 2
An image-side surface of the Nth lens element counted from the object side to the image side along the optical axis is cemented to an object-side surface of the N+1th lens element counted from the object side to the image side along the optical axis
Data Source
AI summary
Disclosed is an optical imaging lens including a first lens element, a second lens element, a third lens element and a fourth lens element arranged in a sequence from an object side to an image side along an optical axis. Refracting power of the second lens element is positive. An image side surface of the Nth lens element counted from the object side to the image side along the optical axis is cemented to an object side surface of the N+1th lens element counted from the object side to the image side along the optical axis, and N is a positive integer greater than or equal to 1 and less than or equal to 3. The optical imaging lens satisfies: EFL/Fno≥2.200 mm, wherein EFL is an effective focal length of the optical imaging lens, and Fno is a f-number of the optical imaging lens.