Convex Cemented-Lens Zoom Design for Wide-Angle Imaging
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Solution Overview
Problem
Negative lead type zoom lenses face challenges in correcting aberrations while achieving a compact optical system and wide angle of view, particularly with significant magnification chromatic aberrations at wide angles.
Innovation Solution
A zoom lens configuration with a first lens unit having negative refractive power, a middle group of cemented lenses convex toward the object side, and a last lens unit with positive refractive power, adhering to specific inequalities to correct aberrations and maintain a compact size.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of moving object
If the refractive power of the first lens unit is increased to achieve a wide angle of view, then the angle of view is widened, but magnification chromatic aberrations occur significantly
Solution Approach 1:
The first lens unit is divided into multiple negative lens elements (at least two) with different refractive powers and dispersion characteristics. This segmentation allows each element to contribute differently to the overall optical function, enabling wide angle of view while correcting chromatic aberrations through the combined effect of multiple elements rather than relying on a single strong negative lens
Solution Approach 2:
Different lens elements within the first lens unit are assigned different local optical properties (refractive indices, dispersion values) to address specific aberration issues at different regions of the optical system. This allows targeted correction of chromatic aberrations in the wide-angle range while maintaining the overall wide angle of view capability
2Reliability
If lens units closer to the image side are configured appropriately to correct aberrations, then optical performance is improved, but the complexity of the optical system increases
Solution Approach 1:
The patent extracts and addresses the most critical aberration correction requirements by optimizing specific lens elements in the middle group and rear group, rather than uniformly complicating the entire optical system. Key elements are selectively designed with specific properties to correct the most significant aberrations while keeping other parts of the system relatively simple
Solution Approach 2:
The patent employs parameter changes by selecting lens materials with specific refractive indices and dispersion values, and by optimizing curvature radii and thicknesses of specific lens elements. These parameter optimizations enable effective aberration correction through precise control of optical properties rather than through increased system 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
The configuration achieves high optical performance with a wide angle of view by effectively correcting aberrations such as magnification chromatic aberration, field curvature, and distortion, while maintaining a compact optical system.
Implementation Method 1
a zoom lens consists of a first lens unit L1 having negative refractive power, a middle group Lm including one or more lens units, and a last lens unit L4 having positive refractive power that are arranged in an order from an object side to an image side
Data Source
AI summary
A zoom lens L0 consists of a first lens unit L1 having negative refractive power, a middle group Lm including one or more lens units, and a last lens unit having positive refractive power. The first lens unit L1 includes a first negative lens, a second negative lens, and a third negative lens that are arranged sequentially in an order from an object side to an image side. The number of negative lenses included in the first lens unit L1 is four or less. The middle group Lm includes a plurality of cemented lenses each having a cemented surface that is convex toward the object side, and includes a lens element Ln that is disposed closest to the image side among lens elements having negative refractive power included in the middle group Lm. The zoom lens L0 satisfies a predetermined inequality.