Optical System with Floating Focus Lens Units
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Solution Overview
Problem
Existing image pickup optical systems face challenges in maintaining reduced aberration variation and enhanced optical performance across various object distances, particularly at short distances, while striving for compact and lightweight focus lens units that facilitate high-speed focusing.
Innovation Solution
The optical system incorporates a configuration with multiple lens units, including focus lens units with negative refractive power and an intermediate lens unit with positive refractive power, where the movement of these lens units during focusing is optimized to minimize aberrations, with specific conditional expressions governing their movement and focal lengths to achieve reduced dimensions and weight.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a shorter photographing distance is used to achieve macro photography, then the ability to photograph close objects is improved, but various aberrations are significantly increased resulting in deteriorated optical performance
Solution Approach 1:
The patent employs a floating focus mechanism where multiple lens units (specifically the second and third lens units) move independently during focusing. This dynamic configuration allows the optical system to maintain reduced aberrations at various object distances, including macro ranges, by adjusting the relative positions of lens units to compensate for aberration changes as the object distance decreases.
Solution Approach 2:
The patent changes the movement parameters of different lens units during focusing. Specifically, the second lens unit moves toward the image side while the third lens unit moves toward the object side, with their movement amounts satisfying specific conditional expressions. This parameter optimization enables the system to maintain optical performance across different focusing ranges including macro photography.
2Adaptability or versatility
If all components of the image pickup optical system are moved for focusing, then focusing coverage is improved, but the lens units become larger and heavier
Solution Approach 1:
The patent divides the focusing function across multiple lens units rather than moving all components. Specifically, the second and third lens units are designated as focus lens units that move during focusing, while other lens units remain stationary. This segmentation allows effective focusing coverage while reducing the overall weight and complexity of the focusing mechanism.
Solution Approach 2:
The moving lens units serve multiple functions: they enable focusing across various object distances and simultaneously compensate for aberration changes. The second and third lens units, by moving in coordinated fashion, achieve both focusing coverage and aberration correction, eliminating the need for additional dedicated components.
3Reliability
If multiple lens units are moved during focusing to reduce aberration variations, then optical performance is improved, but the complexity of the focusing mechanism increases
Solution Approach 1:
The patent implements a dynamic floating focus mechanism where the second and third lens units move independently during focusing. This allows the system to adaptively compensate for aberration changes at different object distances while maintaining a relatively simple mechanical structure compared to moving all lens units.
Solution Approach 2:
The patent optimizes the movement parameters of the focus lens units by establishing specific conditional expressions for their movement amounts. This parameter optimization achieves effective aberration control while minimizing the mechanical complexity of the focusing mechanism.
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 enhances optical performance across all object distances, from infinity to short distances, while enabling the design of more compact and lightweight focus lens units.
Implementation Method 1
focus lens units LF1 and LF2 each having a negative refractive power, which are moved during the focusing
Implementation Method 2
an intermediate lens unit having a positive refractive power, which is arranged between the two focus lens units
Data Source
Figure 1A~1B
Figure 2A~2B
Figure 3A~3B
AI summary
Provided is an optical system, which retains enhanced optical performance at any object distance, and has compact and light-weight focus lens units. Provided is an optical system including a plurality of lens units, in which an interval between adjacent lens units changes during focusing, the optical system including: a positive lens unit arranged closest to an object side; first and second focus lens units having negative refractive powers configured to move during focusing; and an intermediate lens unit having a positive refractive power and arranged between the first and second focus lens units. The first and second focus lens units are configured to move toward an image side during focusing.