Position-Based Laser Triggering for Galvanometer Scanner
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Solution Overview
Problem
Current precision laser welding techniques using galvanometer systems result in varying spot overlap due to asynchronous laser pulse frequency with respect to scanner mirror motion, leading to inconsistencies in weld bead placement, especially during acceleration and deceleration phases.
Innovation Solution
A method and system that utilize position command streams and real-time feedback to control galvanometer mirrors and workpiece stages, ensuring uniform laser pulse delivery along a weld path by continuously summing and squaring mirror and stage position feedback signals to determine optimal pulse timing, thereby compensating for velocity variations and optical distortions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If laser pulses are delivered at a fixed frequency while the galvanometer directs the beam along the weld path, then the laser pulsing is simplified and can be timed by a constant frequency clock, but the spot overlap varies at the beginning and end of programmed motion due to speed variations during acceleration and deceleration
Solution Approach 1:
The system uses position feedback from the galvanometer to dynamically adjust laser pulse timing. The controller receives real-time position information and uses it to determine when to trigger laser pulses, ensuring consistent spot overlap despite velocity changes during acceleration and deceleration phases.
Solution Approach 2:
The laser pulse frequency is made dynamic rather than fixed. The system adjusts the pulse frequency in real-time based on the instantaneous velocity of the galvanometer, allowing the pulse timing to adapt to changing motion conditions and maintain uniform spot spacing throughout the weld path.
2Manufacturing precision
If the frequency of laser pulses is changed along the beam path to reduce overlap variation, then spot overlap consistency is improved, but variability in pulse placement is introduced because the ideal point to modify pulse frequency does not coincide with the change in speed of the scan
Solution Approach 1:
Position feedback provides real-time information about the actual location and velocity of the laser spot. This feedback enables the controller to accurately determine the precise moment when velocity changes occur and trigger laser pulses at the correct positions, eliminating the mismatch between frequency modification points and velocity change points.
Solution Approach 2:
The system replaces the mechanical approach of pre-programming fixed frequency changes with an electronic control system that uses real-time position feedback to dynamically adjust pulse timing. This substitution allows for more precise and flexible control of pulse placement based on actual motion conditions.
3Manufacturing precision
If position feedback is used to determine laser pulse timing without reference to the command stream, then uniform spot overlap is achieved despite velocity variations, but the system complexity increases
Solution Approach 1:
The system uses position feedback from the galvanometer to determine laser pulse timing, replacing complex multi-stream coordination with a simpler feedback-based approach. The controller receives position information and automatically determines optimal pulse timing, reducing the need for complex command stream processing while achieving uniform spot overlap.
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 ensures uniform overlap of weld beads along the weld path, improving precision and consistency by synchronizing laser pulses with the actual vector displacement of the scanner mirrors and workpiece stages, regardless of velocity changes, and correcting for optical distortions like the pincushion effect.
Implementation Method 1
control the positioning of a galvanometer scanned mirror or mirrors to define the path a laser beam will travel to intersect the desired path on the workpiece
Implementation Method 2
delivering a pulse of laser energy to the workpiece such that the laser pulses strike the workpiece at locations that are uniformly overlapped along the path
Data Source
AI summary
A method of directing a laser beam along a desired path on a workpiece and at spaced intervals delivering a pulse of laser energy comprising the steps of: using a position command stream and position feedback to control the positioning of galvanometer scanned mirror or mirrors to define the path a laser beam will travel to intersect the desired path on the workpiece; and using position feedback alone to determine when a pulse of laser energy is delivered to strike the workpiece at locations such that are uniformly overlapped along the path notwithstanding variations in galvanometer mirror velocity.