Retrofocus Lens System for Wide-Angle Aberration Correction
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Solution Overview
Problem
Current image forming optical systems for vehicular cameras face challenges in achieving a wide angle of view with minimal blind spots while maintaining high image quality and low manufacturing costs, particularly in super-wide angle applications where chromatic aberration and astigmatism correction are difficult due to the high off-axial chief ray height.
Innovation Solution
The optical system comprises a lens unit with negative refractive power and a lens unit with positive refractive power, arranged in a retrofocus configuration, where the second lens is biconcave and the sixth lens is biconvex, with specific focal length and curvature conditions to correct chromatic aberration and astigmatism, and includes an aperture stop to optimize axial space and refractive power distribution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a fisheye optical system with a small number of lenses is employed to reduce size and cost, then the number of lenses is reduced, but chromatic aberration and astigmatism correction becomes difficult due to high off-axial chief ray height
Solution Approach 1:
The patent applies parameter changes by optimizing the focal lengths, refractive indices, and curvature radii of the six lens elements to specific ranges. The negative refractive power lens unit (first and second lenses) and positive refractive power lens unit (third, fourth, fifth, and sixth lenses) are designed with precise parameter specifications to correct chromatic aberration and astigmatism while maintaining a compact six-lens structure.
Solution Approach 2:
The patent employs composite materials by selecting lens elements with different refractive indices and Abbe numbers. The first lens has a positive refractive index and positive Abbe number, the second lens has a positive refractive index and positive Abbe number, while the third, fourth, fifth, and sixth lenses have varying refractive indices and Abbe numbers to achieve chromatic aberration correction through material composition.
2Adaptability or versatility
If the half angle of view is increased to exceed 90° to eliminate blind spots, then the angle of view is widened, but image quality deteriorates due to increased aberrations
Solution Approach 1:
The patent achieves a half angle of view exceeding 90° while maintaining image quality by changing the optical parameters of the lens system. The specific configuration of six lenses with controlled focal lengths, refractive powers, and curvature radii enables super-wide angle coverage with corrected aberrations, allowing the system to capture a 180° or greater field of view without significant image degradation.
Solution Approach 2:
The patent utilizes curved lens surfaces with specific curvature radii to achieve the wide angle of view. The first lens has an object-side surface curvature radius and image-side surface curvature radius, the second lens has both surfaces with specific curvatures, and subsequent lenses follow similar patterns. These spherical and aspherical surface curvatures are optimized to handle the extreme angles while correcting aberrations.
3Weight of stationary object
If lens diameter is reduced to decrease weight and cost, then weight and manufacturing cost are reduced, but aberration correction capability deteriorates
Solution Approach 1:
The patent reduces optical system weight by optimizing the diameter and thickness parameters of each lens element. The first lens has a diameter and thickness, the second lens has diameter and thickness, and subsequent lenses have similarly optimized dimensions. These parameter changes enable a compact, lightweight design while maintaining aberration correction through the precise optical configuration.
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 enables a wide angle of view exceeding 90° with reduced lens diameter and weight, effective correction of chromatic aberration and astigmatism, and lower manufacturing costs, while maintaining high image quality and telecentricity.
Implementation Method 1
The lens unit having the negative refractive power comprises, in order from the object side, a first lens, which is a negative lens, and a second lens, which is a negative lens, wherein the lens unit having the positive refractive power comprises, in order from the object side, a third lens, which is a positive lens, a fourth lens, which is a negative lens, a fifth lens, which is a positive lens, and a sixth lens, which is a positive lens
Data Source
AI summary
An image forming optical system which comprises a negative lens unit and a positive lens unit arranged in order from an object side. The negative lens unit includes, in order from the object side, a first negative lens and a second negative lens, or a first negative lens, a second negative lens and a third negative lens. The positive lens unit includes, in order from the object side, a third positive lens, a fourth negative lens, a fifth positive lens and a sixth positive lens, or a fourth positive lens, a fifth negative lens, a sixth positive lens and a seventh positive lens.