Three-Lens Imaging System with Shutter Nesting
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Solution Overview
Problem
The challenge is to develop a small-sized imaging lens with high functionality that maintains high aberration performance and ensures sufficient space for a shutter mechanism, while also considering production performance and cost, particularly for high pixel imaging elements.
Innovation Solution
The imaging lens consists of three lenses with specific refracting powers and shapes, including a first lens with positive power, a second lens with negative power and a concave surface, and a third lens with positive power and a meniscus shape, utilizing aspherical surfaces and potentially diffracting surfaces to optimize power distribution and correct chromatic aberration, while ensuring a wide interval for the shutter mechanism.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the optical diaphragm aperture is arranged as proximate to the object side as possible (before or after the first lens) to ensure telecentric performance, then the telecentric performance is improved, but the small-sized formation becomes difficult due to the need for a shutter mechanism arrangement
Solution Approach 1:
The shutter mechanism is nested within the lens system by arranging it between the first and second lenses, specifically utilizing the air interval D2. This allows the shutter to be housed within the existing lens structure rather than requiring external space, thereby maintaining compact overall dimensions while still enabling effective shutter operation for high pixel imaging elements.
Solution Approach 2:
The patent optimizes the air interval D2 between the first and second lenses along the optical axis to provide sufficient space for the shutter mechanism. By carefully controlling this dimensional parameter, the design creates adequate volume for shutter accommodation without increasing the overall lens diameter or compromising telecentric performance.
2Ease of operation
If the air interval between the first lens and the second lens is increased to arrange the shutter mechanism, then the shutter arrangement is improved, but the aberration performance may deteriorate
Solution Approach 1:
The patent establishes specific parameter ranges for the air interval D2 (0.25D2/f ≤ 0.50) and the focal length f1 (0.7f1 ≤ f1.3) to simultaneously satisfy both requirements. By optimizing these parameters, the design ensures sufficient space for the shutter mechanism while maintaining high aberration correction performance, achieving a balance between mechanical arrangement needs and optical performance.
Solution Approach 2:
The first lens is designed with a specific focal length range (0.7f1 ≤ f1.3) to locally optimize the power distribution in the region where the shutter mechanism is arranged. This localized optimization of the first lens's optical properties ensures that the increased air interval D2 does not compromise overall aberration performance.
3Ease of manufacture
If lenses with similar materials are used to reduce production cost, then the production cost is reduced, but the chromatic aberration correction becomes more difficult
Solution Approach 1:
The patent employs a composite material strategy where the first, second, and third lenses are made from materials with different Abbe numbers (ν1, ν2, ν3). This allows for effective chromatic aberration correction through the combination of materials with complementary optical properties, while still using commonly available lens materials that maintain cost-effectiveness.
Solution Approach 2:
The patent introduces constraints on the Abbe numbers of the lens materials (55 ≤ ν123 and 55 ≤ ν2) to ensure adequate chromatic aberration correction. By specifying these material parameter ranges, the design achieves effective color correction even when using cost-effective lens materials, balancing optical performance with manufacturing considerations.
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 achieves small-sized formation, maintains high aberration function, and effectively corrects chromatic aberration, allowing for efficient image capture with reduced shading and improved telecentric performance, even when using lenses with similar materials to minimize production costs.
Implementation Method 1
a first lens (G1) having a positive refracting power; a second lens (G2) having a concave surface on an object side and having a negative refracting power; and a third lens (G3) having a positive refractive power and a meniscus shape
Implementation Method 2
at least one of an object-side surface and an image-side surface of the first lens (G1) is a diffracting surface
Data Source
AI summary
There is provided an imaging lens including a first lens having a positive refracting power, a second lens having a concave surface on an object side and having a negative refracting power, and a third lens having a positive refractive power and a meniscus shape having a convex surface on the object side and at a vicinity of an optical axis, in order from the object side. The imaging lens satisfies conditional equations below. f designates a focal length of the total system, f1 designates a focal length of the first lens, D2 designates an interval between the first lens and a second lens on an optical axis, ν123 designates an average of Abbe numbers of the first lens, the second lens and the third lens, and ν2 designates the Abbe number of the second lens.0.7<f1/f<1.3 (1)0.25<D2/f<0.50 (2)55<ν123 (3)|ν123−ν2|<5 (4)