Chromatic Multi-Wavelength Laser Optics for Reflective Materials
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Solution Overview
Problem
Current laser systems for processing highly reflective materials are costly and inefficient, particularly when dealing with materials that require high reflectivity in the UV to IR range, as they often necessitate sophisticated control circuits and narrowband fiber lasers with high costs and lower peak power.
Innovation Solution
A cost-efficient fiber laser system utilizing a broadband laser source with a chromatic lens system to generate coaxial beams at fundamental and harmonic wavelengths, where the harmonic beam induces a material state change increasing absorption of the fundamental beam, optimizing energy balance through pulse shape control and fluence ratio adjustment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If narrowband fiber lasers with spectral width less than 2 nm are used to achieve high wavelength conversion efficiency, then conversion efficiency is improved, but cost increases and peak power decreases
Solution Approach 1:
The patent intentionally broadens the spectral width of the laser source from the conventional narrowband (<2 nm) to a broader bandwidth (2-100 nm or more), inverting the conventional approach. This parameter change enables the use of simpler, lower-cost fiber lasers while still achieving effective wavelength conversion through the chromatic aberration mechanism that separates fundamental and harmonic wavelengths in space.
Solution Approach 2:
The patent introduces a chromatic aberration lens system as an intermediary optical element that spatially separates the fundamental wavelength beam from the harmonic wavelength beam. This intermediary component enables the broadband laser source to effectively function for wavelength conversion without requiring sophisticated narrowband laser systems, thereby reducing cost while maintaining conversion efficiency.
2Loss of energy
If sophisticated control circuits are implemented to control pulse power profiles for optimizing wavelength conversion, then conversion efficiency is improved, but device complexity and cost increase
Solution Approach 1:
The patent employs a self-service mechanism where the chromatic aberration lens system automatically spatially separates the fundamental and harmonic wavelengths based on their different wavelengths. This passive optical separation eliminates the need for sophisticated active control circuits to manage pulse power profiles, as the wavelength separation occurs naturally through the chromatic aberration of the lens system.
Solution Approach 2:
The patent replaces the complex electronic control system (mechanical/electrical) with a simple optical system based on chromatic aberration. Instead of using control circuits to dynamically adjust pulse parameters for optimal conversion, the system uses the inherent optical property of chromatic aberration to achieve wavelength separation and effective conversion with minimal electronic control.
3Power
If high power fiber lasers are used to process highly reflective materials at the fundamental wavelength, then processing capability is maintained, but energy efficiency decreases due to low absorption
Solution Approach 1:
The patent segments the laser beam into two distinct wavelength components (fundamental and harmonic) that are spatially separated by the chromatic aberration lens system. The harmonic wavelength component is specifically targeted at the material surface to induce state changes and increase absorption, while the fundamental wavelength component provides the main processing power. This segmentation enables both high power delivery and improved energy efficiency.
Solution Approach 2:
The patent applies preliminary action by using the harmonic wavelength beam to first modify the material surface state before the fundamental wavelength beam performs the main processing. This preliminary surface modification increases the absorption coefficient for the subsequent fundamental wavelength irradiation, thereby improving overall energy efficiency while maintaining high processing power capability.
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 enhances processing efficiency by reducing the power requirements of the laser system, achieving improved absorption and material state changes with a more economical setup, capable of efficiently processing a wide range of materials including metals, dielectrics, and composites.
Implementation Method 1
a chromatic lens system which generates chromatic aberration
Implementation Method 2
the beam at the harmonic wavelength provides a material state change which increases the absorption coefficient of the material for the beam at the fundamental wavelength
Implementation Method 3
the beam at the harmonic wavelength provides a material state change
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 a 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.