Retrofocus Optical System Aspherical Lens Aberration Correction
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Retrofocus type optical systems face challenges in correcting aberrations such as field curvatures and chromatic aberrations of magnification, especially at increased angles of view, while also requiring a reduction in size and maintaining high optical performance.
Innovation Solution
The optical system employs a configuration with a first lens unit having at least three negative lenses and an aspherical surface, along with a second lens unit with positive refractive power, where the aspherical surface's shape and position are defined to correct aberrations and reduce system size, adhering to specific conditional inequalities to optimize refractive power and curvature.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the angle of view is increased in a retrofocus type optical system, then the wide angle capability is improved, but negative refractive power of the object-side lens is increased resulting in increased aberrations
Solution Approach 1:
The optical system is divided into multiple lens units with specific configurations. The object-side lens unit contains multiple lenses including negative and positive power elements arranged in a specific sequence, allowing the wide angle requirement to be met while distributing and correcting aberrations across segmented components rather than relying on a single strong negative lens.
Solution Approach 2:
Different regions of the optical system are assigned different optical properties. The object-side lens unit has specific local characteristics with negative refractive power elements positioned to control peripheral light rays, while the image-side lens unit provides complementary positive power to correct aberrations locally without compromising the overall wide angle capability.
2Manufacturing precision
If the refractive power of each lens is reduced to correct aberrations, then chromatic aberrations and field curvatures are improved, but the size of the optical system cannot be reduced
Solution Approach 1:
At least one lens in the object-side lens unit is configured with an aspherical surface instead of a spherical surface. This aspherical configuration enables effective aberration correction including chromatic aberrations and field curvatures while maintaining compact lens dimensions, resolving the contradiction between aberration correction and size reduction.
Solution Approach 2:
The optical system employs specific parameter relationships defined by conditional expressions. The aspherical surface parameters, refractive powers, and focal lengths are optimized within defined ranges to achieve both compact size and effective aberration correction, allowing the system to meet both requirements simultaneously.
3Adaptability or versatility
If a retrofocus type configuration is used to achieve wide angle of view, then half angle of view greater than 45 degrees is achieved, but significant distortions and chromatic aberrations of magnification occur
Solution Approach 1:
The retrofocus configuration inherently uses asymmetrical lens arrangement with the aperture stop positioned behind the object-side lens unit. This asymmetrical design, combined with the aspherical surface and specific lens power distribution, enables wide angle of view while providing the necessary degrees of freedom to correct distortions and chromatic aberrations of magnification that would be difficult to correct in symmetrical designs.
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 effectively corrects distortions and field curvatures, reduces the optical system's size, and maintains high optical performance even at wide angles of view, while preventing aberrations and chromatic aberrations of magnification.
Implementation Method 1
an aspherical lens surface closest to the object has a shape in which a positive refractive power increases as a distance from an optical axis increases
Data Source
Figure 1
Figure 2
Figure 3
AI summary
An optical system LO includes in this order from an object side to an image side, a first lens unit FL, an aperture stop SP, and a second lens unit RL having a positive refractive power. The first lens unit FL includes at least three negative lenses including in order from the object side to the image side, negative lenses GIN, G2N, and G3N. At least one lens surface of the negative lenses GIN, G2N, and G3N is an aspherical surface that satisfies a predetermined conditional inequality.