Peripheral Light Reduction Stop for Endoscope Brightness Saturation
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Solution Overview
Problem
Ultrasonic endoscopes face challenges in designing an optical image pickup system that allows for clear observation of the insertion direction and target region while preventing interference from air and ensuring effective imaging of deep organ structures, particularly in bronchoscopes where lymph nodes are hard to recognize optically.
Innovation Solution
The optical image pickup system incorporates a peripheral light reduction stop positioned to satisfy specific conditional expressions, optimizing the peripheral light reduction quantity and shielding effective luminous flux, thereby reducing brightness saturation and enhancing image clarity of the ultrasonic transducer and organ structures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the optical system is disposed at a position receding from the ultrasonic transducer at the distal end, then the transducer can easily contact the organ and accommodate balloon attachment, but the optical image may suffer from brightness saturation and reduced clarity in high illuminance regions
Solution Approach 1:
The patent extracts and removes excessive peripheral light from the optical system by introducing a peripheral light reduction stop. This stop specifically blocks oblique light rays that cause brightness saturation in high illuminance regions, thereby extracting the harmful excess light while preserving the useful illumination for clear imaging of the transducer and organ structures.
Solution Approach 2:
The peripheral light reduction stop acts as an intermediary element between the illumination source and the image sensor. It mediates the light path by selectively attenuating peripheral light rays that would otherwise cause overexposure, allowing the optical system to maintain proper brightness levels without requiring changes to the transducer positioning or contact mechanism.
2Illumination intensity
If peripheral light reduction is increased to reduce brightness saturation, then image clarity in high illuminance regions improves, but effective luminous flux may be shielded reducing overall image quality
Solution Approach 1:
The peripheral light reduction stop is designed with spatially varying light reduction characteristics. It applies stronger light reduction to oblique peripheral rays that cause brightness saturation, while maintaining higher transmission for paraxial rays that carry effective imaging information. This local differentiation of light reduction quality allows simultaneous reduction of brightness saturation and preservation of effective luminous flux.
Solution Approach 2:
The patent changes the light reduction parameter selectively across different angular regions of the optical system. By adjusting the light reduction stop's geometry and positioning, it modifies the transmission parameter for peripheral rays versus paraxial rays, achieving optimal balance between brightness saturation reduction and effective flux preservation through parameter optimization.
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 solution enables improved visualization of the ultrasonic transducer and organ structures, reducing brightness saturation and maintaining a clear image field of view, even in regions with high illuminance, thus aiding in accurate diagnosis and treatment.
Implementation Method 1
a peripheral light reduction stop, wherein the peripheral light reduction stop is disposed in a position in an optical axis direction satisfying the following Conditional Expression (1)... a peripheral light reduction quantity in the second direction is smaller than a peripheral light reduction quantity in the first direction by shielding no effective luminous flux in the second direction or reducing shielding quantity of the effective luminous flux
Data Source
AI summary
An image pickup optical system includes an image pickup field of view in which part of an endoscope is reflected, an aperture stop and a peripheral light reduction stop. The peripheral light reduction stop is positioned in an optical axis direction satisfying Conditional Expression (1), in the peripheral light reduction stop, when a side on which part of the endoscope exists in the image pickup field of view is a first direction and a side on which no part of the endoscope exists in the image pickup field of view is a second direction, an opening portion of the peripheral light reduction stop satisfies Conditional Expression (2), and a peripheral light reduction quantity in the second direction is smaller than a peripheral light reduction quantity in the first direction by shielding no effective luminous flux in the second direction or reducing shielding quantity of the effective luminous flux,0.5<|Hch/Haxm|<5 (1),−1.2<(La−|Hch|)/|Haxm|<0.6 (2).