Optical System with Aspherical Meniscus Lens for Wide Angle Imaging
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Solution Overview
Problem
Existing optical systems for imaging apparatuses, such as on-vehicle cameras, face challenges in achieving a wide angle of view while maintaining optical performance and minimizing system size and weight.
Innovation Solution
The optical system comprises a front group with positive refractive power, an aperture stop, and a rear group with positive refractive power. The front group includes a sequence of lenses with specific refractive powers, and the rear group consists of a cemented lens and a meniscus lens with aspherical surfaces, optimizing the ratio of positive power diameter to effective region diameter to enhance image formation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a wide angle of view is achieved using conventional optical systems, then the field of view is expanded, but optical performance degradation and increased system size occur
Solution Approach 1:
The optical system is divided into a front group and a rear group, with the aperture stop positioned between them. The front group includes multiple lenses (first lens with negative refractive power, second lens with negative refractive power, third lens, and fourth lens with positive refractive power) while the rear group includes a cemented lens and a meniscus lens. This segmentation allows each group to be optimized independently for wide angle of view while maintaining optical performance through coordinated design.
Solution Approach 2:
The meniscus lens in the rear group features an aspherical surface on at least one of its object-side or image-side surfaces, with a specific concave shape toward the object side. The spherical surface passing through both edge portions has a concave shape toward the object side in a cross-section including the optical axis. This local quality modification (aspherical surface) is specifically applied to correct field curvatures and magnification chromatic aberrations while maintaining the wide angle of view, thereby resolving the contradiction between expanded field of view and optical performance.
2Weight of stationary object
If the system size and weight are reduced, then portability is improved, but achieving wide angle of view becomes more difficult
Solution Approach 1:
The rear group combines a cemented lens and a meniscus lens into a single compact unit. The cemented lens consists of multiple lenses bonded together, reducing the number of air-glass interfaces and overall volume. This merging of optical elements achieves the wide angle of view requirement while minimizing system size and weight compared to using separate lenses for each function.
3Reliability
If field curvatures and magnification chromatic aberrations are corrected, then optical performance is improved, but system complexity increases
Solution Approach 1:
The aspherical surface of the meniscus lens is defined by specific parameters: the spherical surface passing through both edge portions in the effective region has a concave shape toward the object side, and the ratio Rd of the diameter of the portion with positive power to the diameter of the effective region is constrained (0.80≤Rd≤1.00). By optimizing these parameters, the system corrects field curvatures and magnification chromatic aberrations efficiently without requiring excessive complexity in lens configuration or additional correction elements.
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 a wide angle of view while effectively correcting field curvatures and magnification chromatic aberrations, thereby improving optical performance and reducing system size and weight.
Implementation Method 1
an optical system includes, in order from an object side to an image side, a front group with positive refractive power, an aperture stop, and a rear group with positive refractive power
Data Source
AI summary
An optical system includes, in order from an object side to an image side, a front group with positive refractive power, an aperture stop, and a rear group with positive refractive power, wherein the front group includes, in order from the object side to the image side, a first lens with negative refractive power, a second lens with negative refractive power, a third lens, and a fourth lens with positive refractive power, wherein the rear group includes a cemented lens and a meniscus lens situated closest to the image side, wherein at least one of an object-side surface and an image-side surface of the meniscus lens is an aspherical surface, wherein a spherical surface passing through both edge portions in an effective region of the object-side surface has a concave shape toward the object side in a cross-section including an optical axis, and wherein the specific inequality is satisfied.