Imaging Lens Segmentation for Wide Angle and Low F-Number
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Solution Overview
Problem
Conventional imaging lenses fail to achieve a small F number and wide angle of view while effectively correcting various aberrations across the visible range to the near infrared range, particularly in surveillance and vehicle-mounted cameras.
Innovation Solution
The imaging lens configuration includes a front group with negative refractive power and a rear group with positive refractive power, comprising multiple lenses with specific refractive indices and Abbe's numbers, along with conditional formulas to optimize lens placement and material selection, ensuring a small F number and wide angle of view while correcting aberrations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of moving object
If conventional retro focus type lens systems are used, then the angle of view can be widened, but the F number cannot be made sufficiently small
Solution Approach 1:
The lens system is divided into a front group with negative refractive power and a rear group with positive refractive power. This segmentation allows the front group to widen the angle of view while the rear group maintains the F number, resolving the contradiction between these two parameters.
Solution Approach 2:
Different parts of the lens system are assigned different optical properties: the front group has negative refractive power optimized for wide angle, while the rear group has positive refractive power optimized for F number control. This local optimization resolves the contradiction between angle of view and F number.
2Area of moving object
If the angle of view is widened, then the field of view increases, but various aberrations cannot be favorably corrected
Solution Approach 1:
The lens is segmented into multiple groups with different refractive powers and material properties. The front negative group handles wide angle requirements while the rear positive group corrects aberrations, allowing both wide angle of view and good aberration correction.
Solution Approach 2:
The patent specifies particular ranges for refractive indices (nd) and Abbe's numbers (vd) for different lens groups. By using composite material selection with specific optical properties, the system achieves both wide angle of view and effective aberration correction across visible to near-infrared wavelengths.
3Illumination intensity
If the F number is made small, then light gathering ability improves, but the angle of view cannot be sufficiently widened
Solution Approach 1:
The division into front negative group and rear positive group allows independent optimization: the front group contributes to wide angle of view while the rear group maintains small F number, achieving both light gathering ability and wide field of view simultaneously.
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 results in an imaging lens that achieves a small F number, wide angle of view, and high optical performance, effectively correcting various aberrations from the visible range to the near infrared range, suitable for digital cameras, surveillance cameras, and vehicle-mounted cameras.
Implementation Method 1
a front group having a negative refractive power and a rear group having a positive refractive power, provided in this order from the object side to the image side
Data Source
AI summary
An imaging lens is constituted by, in order from the object side to the image side: a negative front group; a stop; and a positive rear group. The front group is constituted by, in order from the object side to the image side, a front group negative lens group, constituted by at least two negative lenses, and a front group positive lens group including one negative lens and one positive lens, in which a positive lens is provided most toward the object side. The rear group includes one negative lens and one positive lens. Conditional Formula (1) below is satisfied:Nan+0.01·νan<2.15 (1)wherein Nan and νan respectively are the refractive index with respect to the d line and the Abbe's number with respect to the d line of the negative lens provided most toward the image side within the front group positive lens group.