Optical System Lens Grouping for Fast Autofocus and Aberration Correction
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Solution Overview
Problem
Existing optical systems face challenges in achieving a balance between reduced size, high optical performance, large aperture ratio, and high autofocus speed, particularly in correcting aberrations during focusing.
Innovation Solution
The optical system is designed with a specific arrangement of lens units, including a front group and a rear group, where certain lens units move during focusing to correct aberrations, particularly astigmatism, coma, and lateral chromatic aberration, while maintaining a compact size and high focusing speed.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If a conventional optical system design is used, then the structure is simple, but it cannot achieve both reduced size and high optical performance with large aperture ratio
Solution Approach 1:
The optical system is divided into multiple lens units with specific refractive powers arranged in front and rear groups. The front group includes lens units with positive and negative refractive powers, while the rear group includes lens units with positive refractive power. This segmentation allows each group to contribute differently to aberration correction, enabling compact design while maintaining high optical performance and large aperture ratio.
Solution Approach 2:
The optical system employs an inner focus mechanism where the first and second focus lens units move relative to the image plane during focusing operations. This dynamic adjustment allows the system to maintain optimal optical performance across different focusing distances while keeping the overall system compact. The movement of focus lens units enables fast autofocus speed without compromising aberration correction.
2Illumination intensity
If the aperture ratio is increased, then the light gathering ability is improved, but aberration correction becomes more difficult
Solution Approach 1:
Different lens units in the optical system are assigned specific refractive powers and positions to address local aberration issues. The front group contains both positive and negative refractive power lens units to correct specific aberrations, while the rear group contains positive refractive power lens units. This local optimization of optical properties in different parts of the system enables large aperture ratio while maintaining effective aberration correction.
3Speed
If the focusing speed is increased, then the autofocus performance is improved, but aberration correction during focusing may deteriorate
Solution Approach 1:
The optical system uses a multi-unit focus mechanism where the first focus lens unit in the front group and the second focus lens unit in the rear group move during focusing. This dynamic configuration allows fast focusing speed while maintaining aberration correction capability. The coordinated movement of multiple lens units enables rapid focus adjustment without sacrificing optical quality.
Solution Approach 2:
The focusing function is segmented across multiple lens units rather than relying on a single moving element. The front group's first focus lens unit and the rear group's second focus lens unit work together during focusing operations. This segmentation of the focusing function allows for faster response time while distributing the aberration correction burden across multiple elements, maintaining optical performance during rapid focus changes.
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 effectively corrects various aberrations and achieves fast focusing with reduced weight and size, ensuring high optical performance across different focusing distances.
Implementation Method 1
a first lens having positive refractive power and disposed closest to an object, and a second lens having negative refractive power and disposed adjacent to and on the image side of the first lens
Data Source
AI summary
An optical system includes, in order from an object side to an image side, a front group having positive refractive power and including a plurality of lens units, an aperture stop, and a rear group having positive refractive power and including a plurality of lens units. During focusing, a first focus lens unit included in the front group and a second focus lens unit included in the rear group move, and thereby a distance between adjacent lens units change. The front group includes a first lens having positive refractive power and disposed closest to an object, and a second lens having negative refractive power and disposed adjacent to and on the image side of the first lens.