Multi-Wavelength Laser Optics for Reflective Material Processing
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Solution Overview
Problem
Current fiber laser systems for processing highly reflective materials are costly and inefficient, particularly when dealing with materials that require specific wavelength absorption for effective processing, as they often necessitate sophisticated control circuits and narrowband lasers with high costs and lower peak power.
Innovation Solution
A cost-efficient fiber laser system that uses a broadband laser source with a spectral width of at least 2 nm, converting the fundamental beam into harmonic wavelengths, and employing a chromatic lens system to achieve axial chromatic aberration, allowing for independent control of beam parameters and fluence ratios to enhance material state changes and absorption efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If narrowband fiber lasers are used to achieve high conversion efficiency, then wavelength conversion efficiency is improved, but system cost increases and peak power decreases
Solution Approach 1:
The patent changes the spectral parameter from narrowband to broadband (at least 2 nm spectral width) and adjusts the temporal pulse shape with an initial spike to achieve high wavelength conversion efficiency without requiring expensive narrowband lasers. The broadband approach combined with pulse shaping maintains conversion efficiency while reducing system cost and increasing peak power capability.
2Manufacturing precision
If sophisticated control circuits are used to control pulse power profile, then processing precision is improved, but device complexity increases
Solution Approach 1:
The patent implements preliminary action by pre-shaping the pulse temporal profile with an initial power spike before the material processing occurs. This pre-shaped pulse automatically provides the desired processing effect (melting the surface to increase absorption) without requiring complex real-time control circuits during operation, thereby achieving high processing precision with simpler control systems.
3Productivity
If fundamental wavelength beam is used for processing, then processing capability for certain materials is improved, but absorption efficiency deteriorates due to high reflectivity
Solution Approach 1:
The patent employs periodic action by using pulsed laser operation with a temporal profile that includes an initial power spike. The pulsed regime allows the material surface to be rapidly heated and melted during the pulse spike, transforming the surface properties periodically to enhance absorption of subsequent pulses at the fundamental wavelength, thereby overcoming the high reflectivity issue while maintaining processing capability.
Solution Approach 2:
The patent utilizes phase transitions by employing the harmonic wavelength beam to melt the material surface during the initial power spike of each pulse. This phase transition from solid to liquid state fundamentally changes the optical properties of the surface, transforming it from highly reflective to highly absorptive for the fundamental wavelength, thereby enabling efficient energy coupling for subsequent processing.
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 significantly reduces the cost and complexity of laser systems while achieving higher efficiency in material processing by optimizing energy balance and wavelength conversion, allowing for effective processing of materials that were previously difficult or inefficient to treat.
Implementation Method 1
converting the fundamental beam into harmonic wavelengths
Implementation Method 2
employing a chromatic lens system to achieve axial chromatic aberration
Implementation Method 3
one of the beams, typically the second beam at the harmonic wavelength is at least partially absorbed to induce a change of the material state in which the absorption of the beam at the fundamental wavelength is increased
Data Source
AI summary
A multiple wavelength laser processing system is configured with a multiple wavelength laser source for generating a multiple wavelength coaxial laser processing beam. The laser processing system further includes a multiple wavelength optical system to deliver the coaxial laser processing beam to a laser-material interaction zone on the surface of a workpiece such that each of the first and a second laser wavelengths in the processing beam impinge at least a portion of the interaction zone as respective first and second concentric laser spots. The multiple wavelength optical system includes a multiple wavelength beam collimator, a configurable chromatic optic, and a laser processing focus lens, wherein the configurable chromatic optic provides an adjustment to the relative focus distance of the first and second laser wavelengths.