Oscillating Multimode Fiber Laser Illumination Speckle Reduction
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Solution Overview
Problem
Laser illumination devices face the challenge of speckle formation due to coherent light interference, which existing methods struggle to fully address, especially in applications like endoscopes where high-intensity and narrow-band illumination is required.
Innovation Solution
The method involves using a multimode propagation path and an oscillation mechanism to dynamically change the incidence position and angle of coherent light on an incidence surface, employing an optical fiber scanner to oscillate the light at high frequencies, thereby reducing speckle patterns through spatial and temporal multiplexing of the illumination.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If laser light source is used for illumination, then illumination intensity and spectral purity are improved, but speckle patterns occur on the subject
Solution Approach 1:
The patent applies dynamics by oscillating the optical fiber at high frequency to dynamically change the light propagation path. This temporal variation in the optical path prevents stable interference patterns from forming, thereby reducing speckle patterns while maintaining the high illumination intensity of laser light
Solution Approach 2:
The patent employs mechanical vibration by oscillating the optical fiber at a high frequency (typically above 1 kHz). This vibration causes the light to sample multiple slightly different paths, which temporal multiplexes the illumination and reduces the visibility of speckle patterns on the subject
2Object-affected harmful factors
If piezoelectric body or air current is used to oscillate optical fiber, then speckle reduction is achieved, but device complexity increases
Solution Approach 1:
The patent applies self-service by using a self-contained piezoelectric oscillator integrated directly into the optical fiber assembly. The piezoelectric body is embedded within the fiber structure, allowing the fiber to oscillate autonomously without requiring external air currents or complex mechanical drive systems, thereby reducing device complexity
Solution Approach 2:
The patent replaces complex mechanical oscillation systems (such as air currents or external mechanical actuators) with a compact piezoelectric actuation system. This substitution integrates the oscillation mechanism directly into the optical fiber, eliminating the need for external mechanical components and reducing overall device complexity
3Object-affected harmful factors
If light diffuser is rotated to reduce speckles, then speckle reduction is achieved, but additional mechanical components are required
Solution Approach 1:
The patent extracts the speckle reduction function from separate mechanical components (such as rotating diffusers) and integrates it directly into the optical fiber through piezoelectric oscillation. This extraction eliminates the need for additional mechanical components like rotating diffusers, thereby reducing device complexity while maintaining speckle reduction effectiveness
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 approach effectively reduces speckle patterns while maintaining high illuminance, achieving a higher speckle reduction effect compared to existing methods, even at higher frequencies, and ensures efficient light propagation without loss.
Implementation Method 1
causing coherent light from a light source to enter a multimode propagation path via an incidence surface
Implementation Method 2
relatively oscillating the light incident on the incidence surface and the incidence surface so as to temporally change at least one of an incidence position and an incidence angle of the light on the incidence surface
Data Source
AI summary
An illumination method includes causing coherent light from a light source to enter a multimode propagation path via an incidence surface, relatively oscillating the light incident on the incidence surface and the incidence surface so as to temporally change at least one of an incidence position and an incidence angle of the light on the incidence surface, and radiating the light that has propagated through the propagation path onto a target.