Wide-Angle Lens Refractive Index Optimization for Ghost Suppression
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Solution Overview
Problem
Wide-angle lenses face challenges in miniaturization, cost reduction, and prevention of ring-shaped ghosts due to deep concave curved surfaces, which complicate lens molding and increase production costs, while also sacrificing productivity and increasing object-to-image distance.
Innovation Solution
A wide-angle lens configuration with a first negative meniscus lens, a second negative lens, a third positive lens, a fourth negative lens, and a fifth biconvex lens, where the first lens has a refractive index exceeding 1.7, reducing its size and sag quantity, and the second lens's sag quantity is controlled to minimize reflections and aberrations, maintaining productivity and shortening the object-to-image distance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the lens surface of the first lens on the image side becomes a deep concave curved surface to widen the angle of view, then the angle of view increases, but lens molding becomes difficult and production cost increases
Solution Approach 1:
The patent changes the refractive index parameter of the first lens to exceed 1.7, which allows the lens to achieve wide-angle performance with a less deep concave surface, thereby easing manufacturing difficulty while maintaining the angle of view
2Adaptability or versatility
If the lens surface of the first lens on the image side becomes a deep concave curved surface to widen the angle of view, then the angle of view increases, but ring-shaped ghosts occur due to multiple reflection
Solution Approach 1:
By increasing the refractive index of the first lens to exceed 1.7, the patent reduces the depth of the concave surface, which in turn reduces multiple reflections between lens surfaces and suppresses the formation of ring-shaped ghosts while maintaining wide-angle capability
3Adaptability or versatility
If design limitations on the second lens and third lens are increased to widen the angle further, then the angle of view increases, but productivity of the second lens decreases
Solution Approach 1:
The patent changes the refractive index parameter of the first lens to exceed 1.7, which redistributes the optical design requirements and reduces excessive design limitations on the second and third lenses, thereby improving their productivity while maintaining wide-angle performance
4Adaptability or versatility
If design limitations on the second lens and third lens are increased to widen the angle further, then the angle of view increases, but object-to-image distance increases
Solution Approach 1:
By increasing the refractive index of the first lens to exceed 1.7, the patent achieves wider angle of view with reduced optical path length, thereby shortening the object-to-image distance while avoiding excessive design limitations on subsequent lenses
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 enables a wider angle of view, reduces lens size and manufacturing costs, suppresses ring-shaped ghosts, and effectively corrects various aberrations, while maintaining productivity and shortening the object-to-image distance.
Implementation Method 1
a refractive index n1 of the first lens satisfies the following conditional expression (1), where n1 denotes a refractive index Nd of the first lens. 1.7 < n1
Implementation Method 2
there is a concern about an occurrence of a ring-shaped ghost caused by multiple reflection between the lens surface of the first lens on the image side and the lens surface of the second lens on the object side
Data Source
AI summary
A wide-angle lens 100 includes a first lens 10, a second lens 20, a third lens 30, a diaphragm 72, a fourth lens 40, and a fifth lens 50. The first lens 10 is a negative meniscus lens whose lens surface on an image side Lb is a concave curved surface. The second lens 20 is a negative lens whose lens surface on the image side Lb is a concave curved surface and whose lens surface on the object side La is convex curved surface. The third lens 30 is a positive lens whose lens surface on the image side Lb is a convex curved surface. The fourth lens 40 is a negative lens whose lens surface on the image side Lb is a concave curved surface. The fifth lens 50 is a biconvex lens. A refractive index n1 of the first lens 10 satisfies a conditional expression.