Coherent Light Waveguide Speckle Noise Reduction
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Solution Overview
Problem
Coherent light illumination systems produce speckle noise due to interference patterns, which is a drawback in applications like inspection lighting, and existing solutions often require bulky optical elements or significant mechanical motion, making them difficult to integrate into laser waveguide systems.
Innovation Solution
A waveguide apparatus with integrated scattering structures inside the waveguide and its coating to redistribute coherent light, creating distinct speckle patterns that can be statically or dynamically superimposed to reduce overall speckle noise, using mechanisms like deformation or changing light coupling to achieve motion between these patterns.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If coherent light is used for illumination, then illumination intensity is improved, but speckle noise increases
Solution Approach 1:
The waveguide is divided into multiple sections with different scattering structures (first scattering structures inside the waveguide core and second scattering structures inside the coating). Each section generates a distinct speckle pattern, and the superposition of these segmented patterns reduces the overall speckle noise while maintaining coherent illumination intensity.
2Object-generated harmful factors
If moving optical elements are used to reduce speckle noise, then speckle contrast is reduced, but device complexity increases
Solution Approach 1:
The patent replaces mechanical moving optical elements with a static waveguide structure containing multiple scattering zones. Instead of mechanically moving a single optical element to decorrelate speckles, the system uses statically defined multiple scattering structures that naturally produce distinct speckle patterns through their different positions and configurations within the waveguide.
Solution Approach 2:
The scattering structures are nested within the waveguide structure - first scattering structures are embedded in the waveguide core while second scattering structures are embedded in the coating layer. This nested arrangement allows multiple scattering functions to be integrated within a single compact waveguide apparatus without requiring separate bulky optical elements.
3Object-generated harmful factors
If bulky optical elements are used to decorrelate speckles, then speckle reduction is achieved, but ease of manufacture deteriorates
Solution Approach 1:
Multiple scattering functions are merged into a single integrated waveguide apparatus. The first scattering structures and second scattering structures are combined within the same waveguide body, eliminating the need for multiple separate bulky optical elements. This integration simplifies manufacturing while achieving effective speckle reduction through the superposition of distinct speckle patterns.
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 in illumination systems by statically or dynamically superimposing speckle patterns within a single waveguide, achieving significant reduction in spatial coherence and noise contrast with minimal motion, suitable for integration into laser waveguide systems.
Implementation Method 1
A waveguide apparatus with integrated scattering structures inside the waveguide and its coating to redistribute coherent light
Implementation Method 2
A waveguide that transports coherent light (e.g., a laser light), with scattering structures inside the waveguide
Implementation Method 3
The resulting random intensity pattern of these illumination systems is a drawback in many applications, e.g. inspection lighting, where the projected speckles are transformed into imaging noise
Data Source
Figure 1
Figure 2a~2c
Figure 3a~3b
AI summary
A waveguide in which coherent light is to propagate along its longitudinal axis has formed therein a first scattering zone (103) that runs along the longitudinal axis and that is to scatter the propagating coherent light (105) out of the waveguide at a non-zero angle relative to the longitudinal axis. Means for vibrating a light spot of the coherent light relative to the waveguide, or means for dynamically changing a focus of the light spot, is provided, so that light coupling of the coherent light into the waveguide changes over time thereby generating different speckle patterns in the waveguide that overlap with the first scattering zone. Other embodiments are also described and claimed including one where a functional or diffusing coating (102) is provided that in combination with the first scattering zone yields a reduced speckle pattern.