Compact Imaging Lens Design for Wide Angle and High Performance
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Solution Overview
Problem
Existing imaging lenses with a small number of lenses fail to achieve high optical performance, compactness, and a wide angle of view, particularly for high pixel count and high performance image sensors, due to issues like large chromatic aberration and astigmatism, and often sacrifice compactness for brightness.
Innovation Solution
A compact imaging lens design comprising a first lens group with negative refractive power and a second lens group with positive refractive power, including a cemented lens configuration that satisfies specific conditional expressions for Abbe numbers and focal lengths, ensuring a wide angle of view and high optical performance with an F-number of about 2.0.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a small number of lenses are used to reduce device complexity, then manufacturing cost and structure are simplified, but optical performance deteriorates due to large chromatic aberration and astigmatism
Solution Approach 1:
The patent combines multiple lens functions into a cemented lens structure where the second group second lens and second group third lens are cemented together. This merging approach reduces the total number of separate lens elements while maintaining the optical correction capabilities needed for high performance imaging.
Solution Approach 2:
The patent employs composite lens design with the cemented lens combining different glass materials with specific Abbe numbers. The second group first lens uses glass with Abbe number 40≤νd2<55, while the cemented lens uses glass with 20<νd3≤35, creating a composite optical system that corrects chromatic aberration with fewer elements.
2Illumination intensity
If lens parameters are optimized for brightness (F-number), then illumination intensity improves, but device length increases sacrificing compactness
Solution Approach 1:
The patent optimizes specific parameter ranges to achieve both brightness and compactness. The conditional expressions define precise parameter ranges: 31≤νd2<40 for the second group first lens and 20<νd3≤35 for the cemented lens, along with specific focal length ratios. These parameter changes enable a bright F2.0 lens while maintaining compact form factor.
3Adaptability or versatility
If a wide angle of view is achieved with compact dimensions, then adaptability improves, but optical performance deteriorates due to increased aberrations
Solution Approach 1:
The patent divides the optical system into distinct functional groups: first lens group with negative refractive power for wide angle capability, second lens group with positive refractive power for focusing, and a cemented lens within the second group for aberration correction. This segmentation allows each group to optimize for its specific function while maintaining overall system performance.
Solution Approach 2:
The aperture stop positioned between the first lens group and second lens group acts as an intermediary element that controls light rays, helping to reduce aberrations while maintaining the wide angle of view capability. This intermediary structure enables the lens to achieve both wide angle and high optical performance.
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 achieves a compact, wide-angle imaging lens with well-corrected aberrations and high optical performance, suitable for high pixel count image sensors, while maintaining brightness and compactness.
Implementation Method 1
a first lens group G1 having a negative refractive power
Implementation Method 2
a second lens group G2 having a positive refractive power
Implementation Method 3
the second group second lens L22 and a second group third lens L23 which are cemented together to form a cemented lens, and the imaging lens satisfies a conditional expression (1): 31≤νd2<40 and 20<νd3≤35
Data Source
AI summary
An imaging lens provided with a negative first lens group and a positive second lens group disposed in order from the object side. The first lens group is composed of a first group first lens which is a negative biconcave single lens, and the second lens group is composed of a positive second group first lens, an aperture stop, a positive second group second lens, and a negative second group third lens disposed in order from the object side. The second group second lens and second group third lens are cemented together to form a cemented lens. The imaging lens is configured to satisfy a conditional expression (3) 0.9<dt3/f<1.3, and further configured to satisfy conditional expression (1) 31<νd2<55 or (1′): 35<νd2 and a conditional expression (2): −10<νd1−νd2<25.