Zoom Lens Wide Angle Aberration Control
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Solution Overview
Problem
Current zoom lenses for electronic cameras, such as broadcast and cinematic cameras, face challenges in achieving extremely wide angles of view while effectively correcting various aberrations, particularly spherical aberration, field curvature, and distortion.
Innovation Solution
A zoom lens configuration comprising a first lens group with fixed positive refractive power, a second lens group with multiple magnification-changing groups, and a third lens group with fixed positive refractive power, arranged in a specific order along the optical axis, where the magnification-changing groups move to achieve a wide angle of view exceeding 110 degrees, while maintaining constant total length and F number, and reducing aberrations through conditional formula satisfaction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If zoom lenses are designed to have wider angles of view, then the angle of view is improved, but aberration correction deteriorates
Solution Approach 1:
The zoom lens is divided into multiple lens groups (first through fourth lens groups) with different functions. The first lens group has positive refractive power and is fixed during magnification change, the second lens group contains negative and positive lens groups for magnification change, the third lens group has positive refractive power and is fixed, and the fourth lens group corrects aberrations. This segmentation allows each group to be optimized for its specific function while working together to achieve both wide angle of view and good aberration correction.
Solution Approach 2:
Different regions of the optical system are given different properties. The first lens group uses positive refractive power to widen the angle of view, while the fourth lens group specifically targets aberration correction. The patent also specifies that the first lens group includes a negative lens with a concave surface toward the object side, and the third lens group includes a positive lens with a convex surface toward the image side, creating local quality variations that balance wide angle performance with aberration control.
2Area of stationary object
If zoom lenses are designed to have wider angles of view, then the angle of view is improved, but the complexity of the lens structure increases
Solution Approach 1:
The zoom lens is divided into multiple lens groups (first through fourth lens groups) with different functions. The first lens group has positive refractive power and is fixed during magnification change, the second lens group contains negative and positive lens groups for magnification change, the third lens group has positive refractive power and is fixed, and the fourth lens group corrects aberrations. This segmentation allows each group to be optimized for its specific function while working together to achieve both wide angle of view and good aberration correction.
Solution Approach 2:
The lens groups serve multiple functions: the first lens group both widens the angle of view and maintains structural stability during zooming, the second lens group handles magnification change while the third lens group provides both structural support and aberration correction, and the fourth lens group corrects aberrations across the zoom range. This multi-functionality reduces the need for additional specialized components.
3Area of stationary object
If the angle of view is widened beyond 110 degrees, then extreme wide angle performance is achieved, but maintaining constant total length and F number becomes more difficult
Solution Approach 1:
The patent specifies dynamic movement of the second lens group during magnification change from wide angle to telephoto end, while the first and third lens groups remain fixed. This dynamic configuration allows the lens to maintain constant total length and F number across the zoom range while achieving extreme wide angle performance exceeding 110 degrees at the wide angle end.
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
The solution enables the achievement of extremely wide angles of view exceeding 110 degrees, suppresses variations in the angle of view during focusing, and minimizes aberrations, resulting in a compact and high-performance imaging apparatus with improved image quality.
Implementation Method 1
a first lens group having a positive refractive power which is fixed while changing magnification
Implementation Method 2
the magnification changing groups respectively moving along an optical axis while changing magnification from a wide angle end to a telephoto end
Implementation Method 3
an aperture stop
Implementation Method 4
a third lens group having a positive refractive power which is fixed while changing magnification
Data Source
AI summary
A zoom lens includes: a first lens group having a positive refractive power which is fixed while changing magnification; a second lens group constituted by two or more magnification changing groups; an aperture stop; and a third lens group having a positive refractive power which is fixed while changing magnification, provided in this order from an object side. The magnification changing groups respectively move along an optical axis while changing magnification from a wide angle end to a telephoto end. The zoom lens satisfies the following conditional formula:u′/u<0.5 (1)wherein u is the angle of inclination of a paraxial chief ray of light that enters the lens surface most toward the object side within the first lens group, and u′ is the angle of inclination of the paraxial chief ray of light that exits the lens surface most toward an image side within the first lens group.