Fish-Eye Lens Aberration Correction via Segmented Power Distribution
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Solution Overview
Problem
Fish-eye lenses used in image pickup apparatuses face challenges with distortion aberration and spherical aberration, particularly in stereographic projection methods, due to inappropriate power arrangements and strong compression effects near the optical axis, which affect image quality and viewing angle.
Innovation Solution
The optical system consists of a front unit with four consecutively arranged negative lenses and a rear unit with positive refractive power, where the focal length ratio of the front to rear units is optimized to reduce aberrations, ensuring a wide viewing angle and compact size, with specific conditional expressions defining the refractive power distribution and lens curvature radii to correct distortion, field curvature, and astigmatism.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a fish-eye lens uses stereographic projection method, then a wide viewing angle of about 180 degrees is achieved, but distortion aberration and spherical aberration become conspicuous
Solution Approach 1:
The optical system is divided into multiple lens units with specific functions: a first lens unit with negative refractive power for wide-angle coverage, a second lens unit with positive refractive power for aberration correction, and a third lens unit with negative refractive power for distortion control. This segmentation allows each unit to address specific optical challenges independently while working together to achieve both wide viewing angle and aberration correction.
Solution Approach 2:
Different regions of the optical system are assigned different optical properties. The first lens unit handles peripheral light rays for wide-angle coverage, the second lens unit corrects spherical aberration through its positive refractive power, and the third lens unit addresses distortion aberration. Each lens unit has specifically designed curvature radii and refractive powers tailored to its local function within the overall system.
2Measurement precision
If three negative lenses are consecutively arranged from the object side to enhance resolution, then resolution is improved, but distortion aberration and spherical aberration remain due to inappropriate power arrangement
Solution Approach 1:
Instead of arranging three negative lenses consecutively as in conventional designs, this invention inverts the power arrangement by introducing a positive refractive power lens unit between negative lens units. The second lens unit with positive refractive power is positioned between the first and third lens units, creating an alternating power distribution that corrects aberrations while maintaining resolution enhancement.
Solution Approach 2:
The invention changes the refractive power parameters by introducing a lens unit with positive refractive power into a system of negative lens units. Specifically, the second lens unit has a positive refractive power that compensates for the negative refractive powers of the first and third lens units, thereby correcting spherical and distortion aberrations while maintaining the resolution benefits of multiple lens elements.
3Volume of moving object
If the optical system is designed for compact size, then the overall dimensions are reduced, but aberration correction becomes more difficult
Solution Approach 1:
The invention merges multiple functions into a compact arrangement by combining wide-angle coverage, spherical aberration correction, and distortion aberration correction into a single integrated optical system. The three lens units work together in sequence, with each unit contributing to multiple objectives simultaneously, thereby achieving comprehensive aberration correction in a compact form factor.
Solution Approach 2:
The patent achieves compact size by optimizing the axial and radial dimensions of the lens units. The conditional expressions constrain the curvature radii and focal lengths to specific ranges that allow the system to maintain short back focal length and overall length while preserving the optical performance needed for aberration correction. This dimensional optimization enables high-performance aberration correction in a compact 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 achieves high optical performance with reduced distortion and spherical aberration, enabling a compact and wide-angle fish-eye lens system that maintains image quality across the entire viewing angle, particularly in stereographic projection methods.
Implementation Method 1
an optical system, including a fish-eye lens
Data Source
AI summary
At least one embodiment of an optical system includes, in order from an object side to an image side, a front unit including a plurality of lenses, an aperture stop, and a rear unit having a positive refractive power. In at least one embodiment, four negative lenses are consecutively arranged from a side of the front unit closest to the object side, and a focal length of the front unit and a focal length of the rear unit are appropriately set.