Imaging Lens Aberration Correction via Cemented Groups
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Solution Overview
Problem
Conventional imaging lenses, such as those used in endoscopes and surveillance cameras, suffer from insufficient correction of various aberrations, leading to suboptimal image quality.
Innovation Solution
The proposed imaging lens configuration includes a front group with at least two negative lenses and a cemented lens, and a rear group with a positive lens and a cemented lens, optimized by specific refractive power and Abbe's number conditions to effectively correct aberrations, including chromatic and spherical aberrations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional lens systems (front group, aperture stop, rear group) are used, then the structure is simple, but aberration correction is insufficient
Solution Approach 1:
The lens system is divided into a front group and a rear group with specific configurations. The front group contains multiple negative lenses and cemented lenses, while the rear group contains positive lenses and cemented lenses, allowing independent optimization of each group for aberration correction
Solution Approach 2:
Cemented lenses are used where lenses with different Abbe's numbers are cemented together. Specifically, a negative lens with a first Abbe's number is cemented to a positive lens with a second Abbe's number (where the second is smaller than the first), creating composite optical elements that correct both chromatic and spherical aberrations
2Manufacturing precision
If more lenses are added to improve aberration correction, then image quality improves, but lens system length increases
Solution Approach 1:
Specific parameter ranges are defined for the lens configuration: the focal length of the front group is set to 0.15f to 0.35f, the focal length of the rear group is set to 0.45f to 0.65f, and the Abbe's numbers satisfy specific relationships. These parameter optimizations allow effective aberration correction within a compact form factor
Solution Approach 2:
The patent optimizes the lens system in multiple dimensions simultaneously: focal length ratios, Abbe's number differences, and physical arrangement of lenses. This multi-dimensional optimization achieves superior aberration correction without proportionally increasing the overall lens length
3Manufacturing precision
If cemented lenses with different Abbe's numbers are used, then chromatic aberration is corrected, but manufacturing complexity increases
Solution Approach 1:
Specific parameter ranges are defined for the lens configuration: the focal length of the front group is set to 0.15f to 0.35f, the focal length of the rear group is set to 0.45f to 0.65f, and the Abbe's numbers satisfy specific relationships. These parameter optimizations allow effective aberration correction within a compact form factor
Solution Approach 2:
The patent optimizes the lens system in multiple dimensions simultaneously: focal length ratios, Abbe's number differences, and physical arrangement of lenses. This multi-dimensional optimization achieves superior aberration correction without proportionally increasing the overall lens length
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 significantly improves image quality by suppressing aberrations, allowing for a wider angle of view, reduced lens system length, and enhanced correction of chromatic aberrations, making it suitable for compact applications like endoscopes and vehicle-mounted cameras.
Implementation Method 1
a cemented lens formed by cementing a negative lens and a positive lens having a smaller Abbe's number with respect to the d line (wavelength: 587.6 nm) than the negative lens
Implementation Method 2
an imaging lens which consists of, in order from the object side to the image side, a front group, an aperture stop, and a rear group
Implementation Method 3
a cemented lens having a positive refractive power as a whole, formed by cementing a positive lens and a negative lens
Data Source
AI summary
An imaging lens is constituted by, in order from the object side to the image side: a front group; an aperture stop; and a rear group having a positive refractive power. The front group is constituted by, in order from the object side to the image side: at least two negative lenses, and a cemented lens formed by cementing a negative lens and a positive lens having a smaller Abbe's number with respect to the d line than the negative lens, provided in this order from the object side to the image side, together. The rear group is constituted by, in order from the object side to the image side: at least one positive lens, and a cemented lens having a positive refractive power as a whole, formed by cementing a positive lens and a negative lens, provided in this order form the object side to the image side, together.