Zoom Lens First Unit Meniscus Aspherical Distortion Correction
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Solution Overview
Problem
Existing zoom lenses with wide angles struggle to achieve both compact structure and high optical performance due to insufficient distortion correction at the wide-angle end, often requiring large first lens unit thickness or improper refractive power settings.
Innovation Solution
A compact zoom lens design featuring a first lens unit with at least three meniscus lenses having negative refractive power and convex shape towards the object side, including an aspherical surface with positive aspherical amount, along with a positive rear lens unit, where intervals between lens units change during zooming, satisfying specific conditional expressions for optimal performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of moving object
If the focal length of the first lens unit is set to be small to widen the angle of view, then the angle of view is improved, but the distortion correction at the wide-angle end deteriorates
Solution Approach 1:
The first lens unit is divided into multiple separate meniscus lenses (at least three pieces) instead of using a single lens. This segmentation allows each lens to contribute to different aspects of optical performance, enabling both wide angle of view and effective distortion correction through coordinated optical paths
Solution Approach 2:
Each meniscus lens in the first lens unit is designed with specific local optical characteristics (negative refractive power, convex shape toward object side, aspherical surfaces) to address specific optical problems at different locations in the optical path, enabling localized optimization of both field of view and distortion correction
2Manufacturing precision
If the thickness of the first lens unit is increased to improve distortion correction, then the distortion correction is improved, but the compact structure deteriorates
Solution Approach 1:
Instead of using a single thick lens for distortion correction, the first lens unit segments the correction function across multiple thinner meniscus lenses. This distributes the optical path length and correction capability while maintaining a compact overall structure
Solution Approach 2:
The meniscus lenses utilize aspherical surfaces with positive aspherical amounts to enhance distortion correction. The curved surfaces provide more effective optical path control compared to flat surfaces, achieving better correction with thinner lens elements
3Device complexity
If the refractive power of the aspherical lens is not properly set relative to the first lens unit, then the structure is simplified, but the distortion correction deteriorates
Solution Approach 1:
The patent establishes specific parameter relationships between the aspherical lens and the first lens unit, particularly defining the aspherical amount within the range of 0.2 to 2.0 and setting the refractive power ratio within -0.05 to -0.5. These parameter constraints optimize distortion correction while maintaining reasonable structural complexity
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 design achieves a wide angle of view with high optical performance across the zoom range while maintaining a compact structure by effectively correcting distortion and reducing lens thickness, thereby enhancing the overall optical performance and mechanical layout.
Implementation Method 1
a first lens unit having a negative refractive power... at least three meniscus lenses each having a negative refractive power and a convex shape toward the object side
Implementation Method 2
At least one of the at least three meniscus lenses includes an aspherical surface having a positive aspherical amount
Data Source
AI summary
A zoom lens consisting of, in order from an object side to an image side, a first lens unit having a negative refractive power, and a rear lens unit having one or more lens units and having a positive refractive power as a whole. Intervals between adjacent lens units change during zooming. The first lens unit has at least three meniscus lenses each having a negative refractive power and a convex shape toward the object side. At least one of the at least three meniscus lenses includes an aspherical surface having a positive aspherical amount. A predetermined condition is satisfied.