Birefringent Aperture Stop for Variable Focal Length Optical Imaging
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Solution Overview
Problem
Inspection devices like borescopes and endoscopes face inefficiencies due to the need to repeatedly change lens tips for different focal lengths, leading to time-consuming operations and reduced inspection efficiency, especially when trying to achieve a large depth of field without resulting in darker images.
Innovation Solution
An optical imaging system incorporating a birefringent element, a light modulating element, and a polarizer element that decomposes un-polarized light into different polarized light beams to form multiple focal lengths, allowing for switching between focal lengths without mechanical control, using a two-mode aperture stop assembly with a polarizer and light modulating elements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Duration of action of stationary object
If a lens system with fixed focal length is designed to achieve a large depth of field, then the depth of field is improved, but the image becomes darker due to the smaller aperture stop used
Solution Approach 1:
The patent applies a variable aperture stop mechanism that can dynamically adjust the aperture size based on the desired focal length. When switching between different focal lengths, the aperture stop automatically changes its opening size to optimize both depth of field and image brightness, resolving the contradiction between these two parameters.
Solution Approach 2:
The system changes the aperture parameter dynamically according to the focal length setting. By coordinating the aperture stop opening size with the selected focal length, the system achieves optimal image brightness for each focal length while maintaining the ability to provide large depth of field when needed.
2Adaptability or versatility
If a set of variety DOF tips with different lenses are used to inspect different distances, then the inspection coverage is improved, but the inspection efficiency decreases due to repeatedly changing tips
Solution Approach 1:
The patent creates a universal lens system that can perform multiple inspection functions (near field, mid field, far field) by adjusting its focal length, eliminating the need for multiple separate lens tips. This single multi-functional lens system replaces what would traditionally require several specialized tips, thereby improving inspection efficiency while maintaining comprehensive coverage.
Solution Approach 2:
The system uses dynamic focal length adjustment to adapt to different inspection distances in real-time, allowing the same lens system to serve multiple inspection scenarios without physical replacement of lens tips, thus maintaining high inspection efficiency across varying inspection requirements.
3Adaptability or versatility
If mechanical control is used to switch between different focal lengths, then the focal length switching is achieved, but mechanical vibrations occur and device complexity increases
Solution Approach 1:
The patent replaces mechanical control mechanisms with an optical solution using a birefringent element and polarizer. This substitution eliminates mechanical moving parts entirely, using optical property changes instead of mechanical adjustments to achieve focal length switching, thereby reducing device complexity and eliminating mechanical vibrations.
Solution Approach 2:
The system introduces a birefringent element as an intermediary optical component that mediates the focal length adjustment process. This intermediary uses optical field manipulation rather than direct mechanical actuation, providing a vibration-free and simpler control mechanism for switching between focal lengths.
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
Enables efficient inspection by automatically or manually switching between focal lengths, reducing the need for mechanical adjustments, minimizing vibrations, and maintaining image quality across varying distances, thus enhancing inspection efficiency and user convenience.
Implementation Method 1
The birefringent element is configured for decomposing un-polarized light into first linear polarized light and second linear polarized light under different refractive indexes to respectively form a first focal length and a second focal length in the optical imaging system
Implementation Method 2
The light modulating element is configured for modulating a state of polarization of the first and second linear polarized light in response to control signals
Implementation Method 3
The polarizer element is configured for filtering out one of the modulated first and second linear polarized light for creating a single image
Data Source
AI summary
An optical imaging system includes a birefringent element, a light modulating element, and a polarizer element. The birefringent element is configured for decomposing un-polarized light into first linear polarized light and second linear polarized light under different refractive indexes to respectively form a first focal length and a second focal length in the optical imaging system. The light modulating element is configured for modulating a state of polarization of the first and second linear polarized light in response to control signals. The polarizer element is configured for filtering out one of the modulated first and second linear polarized light for creating a single image.