Optical System Aberration Control via Dual Focus Lens Movement
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Solution Overview
Problem
Existing image pickup optical systems face challenges in reducing aberration variations during focusing while maintaining high optical performance over a wide range of object distances, particularly from infinity to close proximity, and in downsizing and reducing the weight of the system.
Innovation Solution
The optical system consists of a first lens unit with positive refractive power moving toward the object side and a second focus lens unit with negative refractive power moving toward the image side, with specific conditional expressions governing their movement and configuration to optimize aberration control and system size.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a floating system with multiple lens units is used to reduce aberration variations during focusing, then optical performance is improved, but the device complexity and weight increase
Solution Approach 1:
The lens system is divided into multiple lens units with different refractive powers (positive and negative) that can move independently during focusing. This segmentation allows each unit to contribute differently to aberration correction, enabling effective aberration control while managing overall system complexity through modular design
Solution Approach 2:
The lens units are designed to serve multiple functions: they contribute to both focusing and aberration correction simultaneously. The first focus lens unit with positive refractive power and the second focus lens unit with negative refractive power work together to correct multiple types of aberrations while enabling focusing from infinity to close distances
2Reliability
If lens units are moved during focusing to reduce aberration variations, then optical performance is improved, but the weight of the optical system increases
Solution Approach 1:
The patent specifies precise parameter ranges for the lens units, including the conditional expressions -5.00 < DA/fA < -0.18 and 0.05 < D/f < 0.50. These parameter constraints optimize the balance between aberration correction effectiveness and the weight of moving components, ensuring that the focus lens units move appropriate distances to correct aberrations without excessive weight
3Adaptability or versatility
If the photographing magnification range is increased beyond macro, then versatility is improved, but aberration variations during focusing become noticeable
Solution Approach 1:
The lens system employs dynamic focusing mechanisms where the first and second focus lens units move independently during focusing from infinity to close distances. This dynamic adjustment allows the system to maintain aberration control across a wide magnification range, transitioning smoothly from telephoto to macro photography without significant aberration variations
Solution Approach 2:
Different lens units are assigned different refractive powers (positive and negative) to address specific aberration types at different magnification ranges. The first focus lens unit with positive refractive power and the second with negative refractive power work in combination to correct aberrations locally at each magnification level, enabling high optical performance across the entire range
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 configuration effectively reduces aberration variations and achieves high image quality over the entire object distance range while downsizing and reducing the weight of the optical system, facilitating close-up photography.
Implementation Method 1
a first focus lens unit having a positive refractive power, which is configured to move toward the object side during focusing from infinity to a closest object distance
Implementation Method 2
a second focus lens unit having a negative refractive power, which is configured to move toward the image side during focusing from infinity to the closest object distance
Data Source
AI summary
Provided is an optical system including, in order from an object side to an image side: a first lens unit having a positive refractive power; a first focus lens unit having a positive refractive power and configured to move toward the object side for focusing from infinity to a closest object distance; and a second focus lens unit having a negative refractive power and configured to move toward the image side during focusing from infinity to the closest object distance, and an interval between each pair of adjacent lens units is changed during focusing. Further, a focal length of the first focus lens unit, a movement amount of the first focus lens unit during focusing from infinity to the closest object distance, a focal length of the optical system, and a total lens length of the optical system are each appropriately set.