Multimode Fibre Laser Beam Shaping Without External Optics
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current laser processing technologies face limitations in varying the beam parameter product and focused laser beam size without adjusting optics, leading to inefficiencies in cutting, welding, and additive manufacturing, particularly in handling different metal thicknesses and materials.
Innovation Solution
A laser processing apparatus comprising a laser, an optical fibre, and a coupler that switches between different optical modes to achieve a top-hat or annular laser beam profile, allowing for adjustable beam quality and spot size without moving optics, using a squeezing mechanism and long period grating to couple laser radiation into higher order modes.
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 system cost increases
Solution Approach 1:
The patent changes the optical mode parameters of the laser beam by coupling fundamental mode light into higher-order modes using long period gratings. This allows the beam profile to be transformed from Gaussian to top-hat or annular without external optics, resolving the contradiction between beam profile flexibility and system cost.
Solution Approach 2:
The patent replaces the mechanical/optical system of external beam shaping optics with a photonic structure (long period grating) that performs beam profile transformation through optical mode coupling. This substitution eliminates the need for expensive external optics while achieving the same beam profile flexibility.
2Manufacturing precision
If working distance is changed to adjust spot size, then spot size control is improved, but processing time increases
Solution Approach 1:
The patent changes the optical mode parameters to alter the beam's spatial distribution and effective spot size without changing the working distance. By coupling into higher-order modes, the beam profile and spot characteristics are modified while maintaining a fixed focal position, thus improving processing speed without sacrificing spot size control.
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 dynamically changes the optical mode parameters during additive manufacturing operations. By switching between fundamental mode (for precise features) and higher-order modes (for larger area processing), the system achieves both high precision and high speed, resolving the contradiction between feature size precision and building speed.
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 creates an annular beam profile by coupling fundamental mode light into higher-order modes using long period gratings, rather than using traditional axicon lenses. This approach produces an annular beam with controlled divergence, maintaining low divergence while achieving the surface damage reduction benefits of annular beam drilling.
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
Enables flexible laser processing with improved cutting speed, edge quality, and reduced material damage by varying the beam profile and spot size, optimizing processing for diverse materials and thicknesses without the need for costly optical adjustments.
Implementation Method 1
the optical fibre is such that laser radiation is able to propagate along the optical fibre in a first optical mode having a first mode order, a second optical mode having a second mode order, and a third optical mode having a third mode order
Implementation Method 2
the coupler is configured to switch laser radiation propagating in the first optical mode to laser radiation propagating in the second order mode; and the coupler is configured to switch the laser radiation propagating in the second optical mode to laser radiation propagating in the third order mode
Data Source
AI summary
Apparatus for laser processing a material (11), comprising a laser (1), an optical fibre (2), and a coupler (125), wherein: the laser (1) is connected to the optical fibre (2); the optical fibre (2) is a multimode optical fibre having a first optical mode (21) having a first mode order (24), a second optical mode (22) having a second mode order (25), and a third optical mode (23) having a third mode order (26); the third mode order (26) is higher than the second mode order (25) which is higher than the first mode order (24); the coupler (125) switches laser radiation propagating in the first optical mode (21) to laser radiation propagating in the second optical mode (22); and the coupler (125) switches the laser radiation propagating in the second optical mode (22) to laser radiation propagating in the third optical mode (23).