Endoscope Light Source Speckle Reduction via Moving Diffuser
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Solution Overview
Problem
Endoscope illumination devices using semiconductor lasers suffer from speckle noise due to high coherence, which degrades image quality, and existing techniques have limitations in effectively reducing speckle noise across different wavelengths.
Innovation Solution
An endoscope light source device with a speckle reduction member having thickness variations that create a valid optical path difference, combined with a driver for movement and a light condensing lens to optimize light transmission, ensuring a positive light quantity loss rate and improved image quality by dispersing light phases across wavelengths.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If semiconductor laser light sources are used for illumination, then high luminance and low power consumption are achieved, but speckle noise is generated due to high coherence
Solution Approach 1:
The patent applies dynamics by moving the diffuser relative to the optical path during image capture. This motion dynamically changes the scattering conditions, causing the speckle pattern to shift and average out over time, thereby reducing visible speckle noise while maintaining the high luminance benefits of laser illumination
Solution Approach 2:
The patent introduces a diffuser as an intermediary element between the laser light source and the observation target. This diffuser scatters the coherent laser light, transforming it into partially coherent light that illuminates the target while reducing the speckle effect, thus mediating between the high luminance requirement and the speckle noise problem
2Object-affected harmful factors
If a diffusion member is used to reduce speckles, then speckle noise is reduced, but light quantity loss increases
Solution Approach 1:
The patent uses a moving diffuser that is periodically moved during the imaging process. This dynamic approach allows the system to use a thinner or less aggressive diffuser compared to static designs, reducing light absorption and scattering losses while still achieving speckle reduction through temporal averaging of multiple speckle patterns
Solution Approach 2:
The patent implements periodic motion of the diffuser during image capture. This periodic action creates a time-varying speckle pattern that averages out over the exposure period, achieving speckle reduction with minimal light loss by using the temporal dimension rather than requiring strong spatial diffusion that would absorb or scatter away light
3Object-affected harmful factors
If existing speckle reduction techniques are applied, then some speckle noise is reduced, but effectiveness varies across different wavelengths
Solution Approach 1:
The patent employs a wavelength-independent speckle reduction mechanism based on temporal averaging through diffuser motion. This approach works universally across different wavelengths because it relies on the statistical properties of speckle patterns and temporal integration rather than wavelength-specific optical properties, making it effective for multi-wavelength or broadband laser illumination
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
The solution effectively reduces speckle noise by generating diverse optical path differences, enhancing image quality and maintaining high efficiency in light transmission, thereby improving the overall performance of endoscope illumination systems.
Implementation Method 1
a surface including thickness variation that provides the light with a speckle reduction valid optical path difference or more corresponding to the predetermined wavelength
Implementation Method 2
The speckle reduction member is configured to scatter the entering light
Implementation Method 3
refraction of the light condensing lens
Data Source
AI summary
An endoscope light source device includes a light source to emit light, and a speckle reduction member to scatter the light. The reduction member has a surface including thickness variation to provide the light with an optical path difference. The device also includes a drive to move the reduction member, and a lens to condense the light passed through the reduction member onto a light guide of an endoscope. The surface of the reduction member has inclination of an average inclination angle. The average inclination angle is determined so that a light quantity loss rate of the entering light into the light guide by scattering of the reduction member and refraction of the lens has a positive value equal to or smaller than an effective allowable loss rate.