Zoom Lens Ghosting Reduction via Meniscus Curvature
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Solution Overview
Problem
Wide-angle zoom lenses with negative meniscus lenses suffer from ghosting issues due to light reflection, particularly at the peripheral portions, which affects image quality and is exacerbated by the curvature of these lenses, leading to antireflection weaknesses and ghost appearance.
Innovation Solution
The zoom lens design includes a first lens unit with four or more lenses, featuring a first negative meniscus lens and a second negative meniscus lens with convex surfaces facing the object side, along with specific inequalities for the radius of curvature, focal length, and refractive index to minimize ghosting, and incorporates aspherical lenses to correct aberrations and distortion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a negative meniscus lens with high curvature is used to correct barrel distortion and field curvature, then the correction effect is improved, but light reflection at the peripheral portion increases causing ghost appearance
Solution Approach 1:
The patent applies different surface curvatures to different regions of the lens. Specifically, the first negative meniscus lens has a convex surface facing the object side with a specific radius of curvature relationship (0.9 < G1R2/D1 < 2.0), creating local optical properties that reduce peripheral reflection while maintaining central distortion correction. This local optimization prevents ghost formation at lens periphery while preserving the overall correction function.
Solution Approach 2:
The patent optimizes specific optical parameters including the radius of curvature ratio (G1R2/D1) between 0.9 and 2.0, the focal length ratio (fa/fw) between -2.0 and -4.0, and the refractive index (N1) between 1.8 and 2.0. These parameter changes balance the competing requirements of distortion correction and ghost prevention by fine-tuning the optical path and reflection characteristics.
2Illumination intensity
If the curvature of the meniscus lens is increased to enhance antireflection effect at the center, then the central region performance is improved, but the peripheral portion antireflection effect weakens causing ghost
Solution Approach 1:
The patent creates different optical characteristics for central and peripheral regions through the specific meniscus lens configuration. The convex surface facing the object side with controlled radius of curvature (G1R2/D1 ratio) provides optimal light transmission at the center while the peripheral regions benefit from the overall lens geometry that reduces reflection angles and ghost formation.
3Adaptability or versatility
If a zoom lens with wide-angle capability is designed, then the field of view is improved, but ghosting issues are exacerbated due to the optical configuration
Solution Approach 1:
The patent maintains wide-angle capability (focal length ratio fa/fw between -2.0 and -4.0) while controlling ghosting through optimized parameter relationships. The specific constraints on radius of curvature ratios and refractive indices ensure that the wide-angle optical path does not create excessive peripheral reflection, thus preserving both field of view and image quality.
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 effectively reduces ghosting and enhances image quality by optimizing the refractive power and curvature of lens surfaces, allowing for high-performance wide-angle and high-magnification zoom capabilities while maintaining image clarity.
Implementation Method 1
a first negative meniscus lens G1 having a convex surface facing an object side and a second negative meniscus lens G2 having a convex surface facing the object side... N1 is a refractive index of the first negative meniscus lens
Data Source
AI summary
A zoom lens includes, in order from the object side to the image side, a first lens unit having negative refractive power, a second lens unit having positive refractive power. A distance between adjacent lens units changes during zooming from a wide-angle end to a telephoto end. During zooming from the wide-angle end to the telephoto end, the first lens unit moves to the image side and then to the object side. The first lens unit includes four lenses or more, the four lenses or more including, in order from the object side to the image side, a first negative meniscus lens with a convex surface facing the object side and a second negative meniscus lens with a convex surface facing the object side. A predetermined condition is satisfied.