Multi-Element Laser Light Source Speckle Noise Reduction
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Solution Overview
Problem
Laser light sources suffer from speckle noise, which affects image quality and measurement accuracy due to their high coherence, leading to unwanted flicker patterns on observed surfaces and image sensors.
Innovation Solution
The use of a light source with multiple surface-emitting elements, where the element interval and incident angles are arranged to ensure overlapping light beams create distinct speckle patterns, reducing noise by averaging these patterns through multiple light source angle-multiplexing and wavelength multiplexing techniques.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If a laser light source is used to achieve high-power output and focus-free operation, then power output capability is improved, but speckle noise occurs on the observed surface degrading image quality and measurement accuracy
Solution Approach 1:
The laser light source is divided into multiple independent light emitting elements (e.g., multiple VCSELs or laser diodes) arranged in an array. Each element emits light with slightly different coherence properties and spatial characteristics. By segmenting the single laser source into multiple elements, the patent reduces the overall coherence of the combined light, thereby suppressing speckle noise while maintaining high power output capability through the collective emission of all elements.
2Measurement precision
If multiple light emitting elements are used to reduce speckle noise, then image quality is improved, but the complexity of the light source structure increases
Solution Approach 1:
Multiple light emitting elements are merged into a single integrated light source assembly with unified optical coupling. The patent combines multiple VCSELs or laser diodes into one module that interfaces with a single optical fiber or waveguide array, simplifying the overall system integration. The elements share common mounting structures, electrical connection patterns, and optical alignment mechanisms, reducing the practical complexity despite having multiple emitting elements.
Solution Approach 2:
The array of light emitting elements serves multiple functions simultaneously: it provides high power output through combined emission, reduces speckle noise through reduced coherence, and enables spatial multiplexing for different measurement modes. The same multi-element structure can be configured for different patterns (e.g., line patterns, point patterns) and can operate in various power levels by controlling individual elements, making the light source universally applicable to different measurement requirements.
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 noise by aligning the element intervals and angles to achieve a theoretical noise reduction effect, improving image quality and measurement accuracy without increasing the size or cost of the illuminator.
Implementation Method 1
a plurality of light emitting elements in a surface
Implementation Method 2
hyper-coherence (coherence) which is a characteristic property of laser light causes a spotted pattern flicker called speckle noise to occur in a retina of an eye
Implementation Method 3
hyper-coherence (coherence) which is a characteristic property of laser light
Data Source
AI summary
There is provided an improved light source including a plurality of light emitting elements in a surface. An arrangement of the plurality of light emitting elements fulfills, in an assumed projection area, an element interval at which irradiation light beams of the plurality of light emitting elements overlaps, and fulfills an element interval at which a speckle pattern of each of the irradiation light beams obtained in the assumed projection area is different for each of the irradiation light beams.