Polarization Beam Offsetting for Low-Thermal Laser Machining
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Solution Overview
Problem
Current laser machining techniques using high-power sources face thermal effects that lead to deformation, oxidation, or destruction of workpieces, limiting the use of laser sources above 100 Watts due to conical cutting faces and the inefficacy of gas nozzles in controlling thermal effects.
Innovation Solution
A method and optical device that spatially offset a high-power laser beam into multiple beams with maintained polarization, allowing for precession machining without generating harmful thermal effects by using a spatial offsetting unit and separating unit to create multiple laterally offset laser beams, which can be focused onto workpieces with controlled conicity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If high-power laser sources (>100W) are used for machining, then productivity and machining speed are improved, but thermal effects cause deformation, oxidation, or destruction of workpieces
Solution Approach 1:
The patent divides a single high-power laser beam into multiple spatially offset lower-power beams using beam splitting optics. This segmentation allows the total power to be distributed across multiple beams that can be independently controlled and focused, reducing thermal concentration on the workpiece while maintaining high overall productivity through parallel machining operations.
Solution Approach 2:
The patent employs pulsed laser operation with precise timing control of multiple beams. By using periodic ultrashort pulses rather than continuous illumination, the system allows thermal diffusion time between pulses, preventing cumulative thermal damage while maintaining high average power for productivity. The pulsed regime enables ablation without significant heat accumulation.
2Ease of operation
If a scanner is used to traverse the laser beam across the workpiece, then ease of use and machining speed are improved, but conical cutting faces are generated due to Gaussian beam distribution
Solution Approach 1:
The patent uses multiple separated laser beams instead of a single scanned beam. Each beam can be independently focused and controlled to produce parallel cutting faces. The segmentation of the beam allows simultaneous machining of multiple locations with consistent geometry, eliminating the conical effect inherent in single-beam scanning while maintaining ease of operation through automated beam control.
3Object-affected harmful factors
If gas nozzles are used to cool the workpiece and reduce thermal effects, then thermal damage is reduced, but the nozzles are bulky and can generate pressure that displaces or degrades the target
Solution Approach 1:
The patent removes the need for external gas cooling systems by using ultrashort pulse laser machining. The extremely short pulse duration (femtosecond to picosecond range) delivers energy faster than thermal diffusion can occur, enabling ablation with minimal heat affected zone. This extracts the cooling function from the machining process itself, eliminating bulky gas nozzles and associated complexity while avoiding pressure-related workpiece damage.
Solution Approach 2:
The patent replaces the mechanical gas nozzle cooling system with an optical approach using ultrashort pulse laser physics. Instead of using gas flow to remove heat, the system uses the inherent thermal confinement properties of ultrashort pulses to prevent heat generation in the first place. This substitution eliminates mechanical complexity while achieving superior thermal control.
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 the use of powerful laser sources for machining without thermal damage, allowing for simultaneous multiple machining operations with controlled conicity and power distribution, improving productivity and machining quality.
Implementation Method 1
the spatial offsetting unit being able to maintain the same polarization between the input laser beam and the offset laser beam
Implementation Method 2
a first separation module comprising a first polarization separation means for obtaining from the offset laser beam: the first laser beam spatially offset by transmission, and the second laser beam spatially offset by reflection
Data Source
AI summary
A method for providing a first and a second laser beam, which are spatially offset in relation to an input laser beam. The method includes: providing a laser source for generating the input laser beam; providing a spatial offsetting unit for providing an offset laser beam that can keep the same polarization between the input laser beam and the offset laser beam; providing a separating unit including a first module for separation by polarization in order to obtain, from the offset laser beam: the first laser beam spatially offset by transmission; and the second laser beam spatially offset by reflection, the first and second spatially offset laser beams being suitable for each describing a circle.