Retrofocus Zoom Lens with Segmented Groups for Compact High Resolution
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Solution Overview
Problem
Conventional refractive zoom lens optical systems face challenges in achieving high resolution across varying distances and maintaining a small size, with large size and non-uniform resolution being major issues.
Innovation Solution
A refractive zoom lens system comprising a first lens group with negative refractive power, a second lens group for auto focusing, a third lens group with strong positive refractive power for variable magnification, and a fourth lens group with weak positive power, arranged in a retrofocus structure to reduce aberrations and maintain resolution during focus adjustments, while using aspheric surfaces and plastic materials to optimize size and performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional refractive zoom lens structures are used to achieve high resolution, then resolution is improved, but the optical system size becomes large
Solution Approach 1:
The optical system is divided into four distinct lens groups (first with negative power, second with negative power, third with positive power, fourth with positive power), each serving specific functions. This segmentation allows independent optimization of each group's parameters, achieving high resolution while controlling overall size through coordinated movement of individual groups during zoom and focus operations.
Solution Approach 2:
The patent employs a retrofocus structure where the first lens group has negative refractive power, creating a virtual focus point behind the lens. This dimensional reconfiguration of the optical path allows the optical system to achieve long back focal length with compact physical dimensions, effectively decoupling optical performance requirements from physical size constraints.
2Volume of moving object
If the optical system is made small to reduce TTL/fw ratio, then size is reduced, but uniform resolution across focusing distances cannot be maintained
Solution Approach 1:
The patent implements dynamic focus adjustment by moving the second lens group (with negative power) along the optical axis in response to changing object distances. This dynamic reconfiguration maintains high resolution at both short and long distances. Additionally, the coordinated movement of lens groups during zoom operations ensures uniform resolution across the magnification range while keeping the optical system compact.
3Adaptability or versatility
If zoom range is increased to provide variable magnification, then versatility is improved, but optical system complexity increases
Solution Approach 1:
The zoom function is achieved by segmenting the optical system into four lens groups with specific power distributions, where the third group (positive power) and fourth group (positive power) are moved to vary magnification. This segmentation allows versatile zoom functionality while maintaining a relatively simple overall structure compared to conventional designs, as each group has a defined role in the magnification process.
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 system achieves high resolution during auto focusing from short to long distances and maintains a compact size, with improved optical performance and reduced aberrations, making it suitable for small mobile apparatuses.
Implementation Method 1
a first lens group that is provided close to an object, has a negative refractive power in total... a second lens group that has a negative refractive power in total... a third lens group that has a positive refractive power in total... and a fourth lens group that has a positive refractive power in total
Implementation Method 2
includes an optical part having a surface that reflects light
Data Source
AI summary
A zoom lens optical system includes: a first lens group that is provided close to an object, has a negative refractive power in total, and includes an optical part having a surface that reflects light; a second lens group that has a negative refractive power in total; an iris; a third lens group that has a positive refractive power in total; and a fourth lens group that has a positive refractive power in total.