Multimode Optical Fiber Beam Shaping for Flexible Laser Processing
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Solution Overview
Problem
Current laser processing technologies face limitations in varying the beam parameter product and focused laser beam diameter, which restricts the ability to optimize processing parameters for different metal types and thicknesses, leading to suboptimal cutting, welding, and additive manufacturing results.
Innovation Solution
The use of a multimode optical fibre with a squeezing mechanism and a lens allows for switching between fundamental Gaussian and higher-order modes, enabling the generation of annular or top-hat laser beam profiles, thereby varying the beam waist diameter and divergence without adjusting the working distance, and optimizing the laser processing parameters.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If external optics are used to change beam profile from Gaussian to top hat or annular, then beam profile flexibility is improved, but device complexity and cost increase
Solution Approach 1:
The patent changes the optical mode parameters directly within the optical fiber by controlling the excitation of different modes (fundamental Gaussian mode vs. higher-order modes). By adjusting the excitation conditions, the beam profile can be switched between Gaussian, top-hat, and annular profiles without external optics, thus resolving the contradiction between profile flexibility and device complexity
Solution Approach 2:
The invention extracts the beam profile control function from external optics and relocates it inside the optical fiber through mode selection. This eliminates the need for external beam-shaping optics while maintaining the ability to generate different beam profiles, thereby reducing device complexity and cost
2Area of moving object
If working distance is adjusted to change spot size, then beam spot size is improved, but processing time increases
Solution Approach 1:
The patent changes the beam spot size by selecting different optical modes and adjusting their excitation conditions rather than changing the working distance. This allows rapid switching between different spot sizes without mechanical movement, thereby maintaining high processing speed while achieving variable spot sizes for different processing requirements
3Manufacturing precision
If fundamental Gaussian mode is used for additive manufacturing, then feature size precision is improved, but building speed decreases
Solution Approach 1:
The patent introduces dynamic mode switching capability that allows the system to adapt between fundamental Gaussian mode and higher-order modes based on processing requirements. For small features, the fundamental mode provides precision; for larger areas, higher-order modes enable faster processing. This dynamic adaptability resolves the contradiction between precision and speed in additive manufacturing
4Object-affected harmful factors
If annular laser beam is used for drilling, then surface damage is reduced, but beam divergence increases
Solution Approach 1:
The patent generates annular beams through higher-order optical modes excited within the fiber, and by carefully controlling the mode composition and fiber parameters, achieves low divergence despite the annular profile. This resolves the contradiction by showing that annular beams can maintain low divergence when properly generated through mode control rather than conventional external methods
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 enhances the flexibility and efficiency of laser processing by allowing for precise control of beam profiles, improving cutting speed, edge quality, and material processing capabilities across various metal types and thicknesses.
Implementation Method 1
an optical fibre, such that laser radiation is able to propagate along the optical fibre in a first optical mode and in a second optical mode
Implementation Method 2
a process head, and a lens, for focusing the laser onto the material
Data Source
AI summary
An apparatus for laser processing a material including an optical fibre, at least one squeezing mechanism, and a lens. The optical fibre is a multimode optical fibre in which laser radiation propagates in a first optical mode and in a second optical mode. The squeezing mechanism includes at least one periodic surface defined by a pitch. The periodic surface is located adjacent to the optical fibre. The pitch couples the first and second optical modes together. The first optical mode is defined by a first mode order. The second optical mode is defined by a second mode order which is higher than the first mode order. The squeezing mechanism squeezes the periodic surface and optical fibre together with a squeezing force thereby coupling the first optical mode to the second optical mode.