Variable Divergence Laser Focus Control for Stable Deep Welding
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Solution Overview
Problem
Existing laser processing systems face challenges in dynamically adjusting beam focus during material processing, leading to instability in keyhole formation during welding and inefficient cutting processes, particularly in thick materials, due to static focus limitations.
Innovation Solution
A laser processing system with a divergence-tuning beam characteristic conditioner that oscillates or switches between different divergences, using a fiber assembly with a collimating and focusing lens to dynamically adjust the focus location within the workpiece, enabling variable divergence laser beams for improved penetration and stability during welding and cutting.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If a static focus lens is used in laser processing, then the optical system is simple and stable, but the beam cannot dynamically adjust focus depth leading to poor penetration and instability in keyhole formation during welding and cutting
Solution Approach 1:
The patent applies dynamics by replacing the static focus lens with a dynamic focus adjustment mechanism using a deformable mirror. The deformable mirror can rapidly change its surface curvature in response to control signals, enabling real-time adjustment of beam focus depth without mechanical movement of the entire optical system. This resolves the contradiction by providing dynamic adaptability while maintaining optical system stability through electronic control rather than mechanical reconfiguration.
Solution Approach 2:
The patent changes the optical parameter (focal length) dynamically by using a deformable mirror to alter the wavefront curvature of the laser beam. By controlling the mirror surface shape through actuator displacement, the system can vary the effective focal length and focus position without changing physical lens positions. This parameter change approach enables rapid focus adjustment for different processing depths and materials, improving processing speed without requiring complex mechanical lens positioning systems.
2Reliability
If free-space optics with rapidly moving lens is used for focus adjustment, then dynamic focus is achieved, but mechanical complexity and instability increase
Solution Approach 1:
The patent replaces the mechanical lens positioning system with a non-mechanical wavefront modulation approach using a deformable mirror. Instead of physically moving lenses to change focus, the system uses electronic control of mirror surface shape to alter beam convergence. This substitution eliminates mechanical complexity and associated instability while achieving reliable dynamic focus adjustment, directly improving keyhole stability during welding and cutting operations.
Solution Approach 2:
The deformable mirror serves as an intermediary element between the laser source and the workpiece, mediating the beam's wavefront characteristics. By introducing this intermediate component, the system can adjust focus properties without direct mechanical interaction with the optical path or workpiece, reducing mechanical complexity and improving reliability. The mirror translates electrical control signals into optical wavefront modifications, enabling stable and precise focus control.
3Adaptability or versatility
If phased array solution with multiple laser sources is used, then dynamic focus effect is achieved, but system complexity and cost increase significantly
Solution Approach 1:
The patent applies universality by using a single laser source combined with a deformable mirror to achieve multiple beam characteristics and focus positions. The deformable mirror can be programmed to produce different wavefront shapes, enabling the same optical system to adapt to various processing requirements (different depths, materials, and beam profiles) without requiring multiple laser sources or complex optical assemblies. This multi-functional approach reduces system complexity while maintaining high adaptability.
Solution Approach 2:
The patent uses wavefront copying principles where the deformable mirror replicates desired wavefront shapes that would otherwise require complex multi-source phased array systems. By electronically controlling mirror surface topology, the system can create virtual copies of focused beams at different positions and angles from a single physical source, achieving phased array functionality without the associated complexity and cost of multiple synchronized laser sources.
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 results in deeper penetration welding, improved keyhole stability, and enhanced edge quality during cutting thick materials, while reducing the need for mechanical movements and increasing processing speed and efficiency.
Implementation Method 1
a collimating lens configured to receive the variable divergence laser beam and direct it as an intermediate beam to the focusing lens
Implementation Method 2
a focusing lens configured to focus the intermediate beam toward the workpiece at a first depth corresponding to the first divergence and at a second depth corresponding to the second divergence
Data Source
AI summary
A laser processing system has a laser source and a divergence-tuning beam characteristic conditioner configured to, in response to a control input, repetitively change a variable divergence laser beam between a first divergence and a second divergence that is different from the first divergence. The system also includes a process head having a collimating lens and a focusing lens. And the system includes a delivery fiber coupled to the divergence-tuning beam characteristic conditioner for guiding the variable divergence laser beam and launching it to the process head. The collimating lens is configured to receive the variable divergence laser beam and direct it as an intermediate beam to the focusing lens to focus the intermediate beam toward the workpiece at a first depth corresponding to the first divergence and at a second depth corresponding to the second divergence.