Compact Lens Optical System with Lightweight Focusing Group
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Solution Overview
Problem
Conventional interchangeable lenses for compact system cameras face challenges in achieving fast auto-focusing speeds due to the weight of the focusing lens group, which also complicates the miniaturization and portability of camera systems, especially when using full-frame imaging devices.
Innovation Solution
A lens optical system with a focusing lens group comprising two or less lenses, utilizing a first and third lens group with fixed positions and a movable second lens group, incorporating aspheric lenses to minimize weight and correct image distance changes, while maintaining a constant overall length and ensuring high-resolution performance across various object distances.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If a conventional interchangeable lens with multiple focusing lenses is used, then the focusing operation can correct image distance changes, but the focusing lens group becomes heavy and slows down auto-focusing speed
Solution Approach 1:
The patent extracts the focusing function from a heavy multi-lens group and concentrates it into a single lightweight lens (L4). This single lens L4 is specifically designed with high refractive power to handle the focusing operation, while other lenses remain stationary, thereby dramatically reducing the weight of the moving focusing group and enabling faster auto-focusing.
Solution Approach 2:
The patent changes the optical parameters by introducing a lens (L4) with exceptionally high refractive power (nd=2.00129). This parameter change allows a single lens to perform the focusing function that previously required multiple lenses, reducing the mass of the moving focusing group while maintaining the necessary optical correction capabilities.
2Reliability
If a full-frame imaging device is used with interchangeable lenses, then high-quality photographs can be obtained, but the lens system becomes large and heavy, reducing portability
Solution Approach 1:
The patent employs lenses with high refractive indices (nd values ranging from 1.4978 to 2.00129) to increase the optical power density. This allows the lens system to achieve the required imaging performance for full-frame sensors with fewer and smaller lens elements, thereby reducing the overall weight and size while maintaining photograph quality.
Solution Approach 2:
The patent incorporates aspherical lens surfaces (indicated by negative K values ranging from -0.5 to -6.0) to correct aberrations more efficiently. This allows for a more compact lens design with fewer elements, reducing weight while maintaining high image quality across the full-frame sensor area.
3Length of moving object
If the overall length of the lens system is reduced for miniaturization, then portability improves, but controlling aberrations and maintaining performance becomes difficult
Solution Approach 1:
The patent uses aspherical surfaces with carefully designed curvature parameters (K values and higher-order coefficients) to correct various aberrations within a compact form factor. The aspherical shapes allow for more precise control of light paths, enabling effective aberration correction despite the reduced overall length of the lens system.
Solution Approach 2:
The patent combines lenses with different refractive indices and dispersion characteristics (varying nd and vd values) to create a composite optical system. This allows for effective aberration correction through the synergistic interaction of different lens materials, achieving high manufacturing precision in a miniaturized design.
4Reliability
If an inner type focusing mechanism is used to fix overall length, then dust and water resistance improves, but the focusing lens group must still move significant mass
Solution Approach 1:
The patent extracts the focusing function from a heavy multi-lens group and concentrates it into a single lightweight lens (L4). This single lens L4 is specifically designed with high refractive power to handle the focusing operation, while other lenses remain stationary, thereby dramatically reducing the weight of the moving focusing group and enabling faster auto-focusing.
Solution Approach 2:
The patent changes the optical parameters by introducing a lens (L4) with exceptionally high refractive power (nd=2.00129). This parameter change allows a single lens to perform the focusing function that previously required multiple lenses, reducing the mass of the moving focusing group while maintaining the necessary optical correction capabilities.
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 enables fast auto-focusing speeds, maintains high-resolution performance, and enhances portability by reducing the overall length and weight of the lens system, while effectively controlling aberrations and ensuring dust and water resistance.
Implementation Method 1
a first lens group G11 having a positive refractive power, a second lens group G21 consisting of two or less lenses and having a positive refractive power, and a third lens group G31 having a negative refractive power
Data Source
AI summary
A lens optical system includes a first lens group having a positive refractive power, a second lens group consisting of two or less lenses and having a positive refractive power, and a third lens group having a negative refractive power. The second lens group is configured to perform a focusing operation to correct a change in an image distance dependent on a change in an object distance, and the first lens group and the third lens group are fixed and the overall length of the lens optical system does not change during the focusing operation.