Laser Machining OCT Scanning for Vapor Capillary Depth Tracking
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Solution Overview
Problem
Existing laser machining systems, particularly scanner-based systems, face challenges in accurately determining the depth and position of the vapor capillary during laser welding due to chromatic aberration, varying angles, thermal influences, vibrations, and fluctuating material properties, leading to unreliable and inefficient optical coherence tomography measurements.
Innovation Solution
Adapt the scanning area for the optical measuring beam based on current laser machining parameters, such as machining speed and direction, to ensure the beam accurately hits the vapor capillary, using a first deflection device for the machining laser beam and a second deflection device for the optical measuring beam, allowing for real-time adjustment of the scanning area to improve measurement reliability and accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a fixed scanning area is used for the optical measuring beam, then the system structure is simple, but the measurement precision deteriorates due to chromatic aberration and varying angles in scanner-based systems
Solution Approach 1:
The patent applies dynamics by making the scanning area adjustable and adaptive rather than fixed. The scanning area is dynamically modified based on current process parameters (machining speed, direction, laser power) to track the vapor capillary position accurately despite chromatic aberration and angle variations in scanner-based systems.
Solution Approach 2:
The patent changes parameters by modifying the scanning area dimensions and position based on process parameters. The control unit adjusts the scanning area parameters (size, shape, location) in real-time according to machining conditions, enabling accurate vapor capillary measurement under varying operational states.
2Reliability
If the scanning area is enlarged to account for position variations, then the reliability of hitting the vapor capillary improves, but the measurement precision deteriorates due to including areas outside the capillary
Solution Approach 1:
The scanning area is dynamically adjusted to maintain optimal size - large enough to ensure reliable vapor capillary detection despite position variations, but small enough to exclude irrelevant areas. The scanning area adapts its dimensions based on real-time process parameters to balance reliability and precision.
Solution Approach 2:
The system uses feedback by continuously monitoring process parameters (machining speed, direction, laser power) and adjusting the scanning area accordingly. This closed-loop control ensures the scanning area remains optimally positioned and sized to maintain both reliability of detection and precision of measurement.
3Measurement precision
If the scanning area is reduced to improve measurement precision, then the signal-to-noise ratio improves, but the reliability deteriorates due to smaller target area for vapor capillary detection
Solution Approach 1:
The scanning area is dynamically optimized to achieve the minimal size required for reliable vapor capillary detection. By adapting the scanning area size to current process conditions, the system maintains high signal-to-noise ratio while ensuring the vapor capillary remains within the scanning boundaries for reliable detection.
4Productivity
If high machining speeds are used to increase productivity, then the production output improves, but the measurement precision deteriorates due to increased offset between vapor capillary and machining laser beam positions
Solution Approach 1:
The scanning area is dynamically adjusted in response to machining speed changes. At high machining speeds where the offset between vapor capillary and laser beam increases, the scanning area is modified to account for this larger displacement, maintaining measurement precision despite high productivity requirements.
Solution Approach 2:
The system changes parameters by adjusting the scanning area position and dimensions based on machining speed. When machining speed increases, the scanning area parameters are modified to compensate for the increased offset, ensuring continuous accurate vapor capillary measurement across the full range of productivity levels.
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
Enhances the reliability, speed, and accuracy of determining the vapor capillary depth and position by increasing the signal intensity and number of measurements from the capillary, reducing the need for filtering and improving the signal-to-noise ratio.
Implementation Method 1
depth and distance measurements have been carried out without contact using optical coherence tomography (OCT for short). For this purpose, an optical measuring beam, also known as OCT measuring beam, from an optical coherence tomograph is irradiated onto the workpiece and part of the optical measuring beam is reflected back from the workpiece into the optical coherence tomograph.
Implementation Method 2
part of the optical measuring beam is reflected back from the workpiece into the optical coherence tomograph
Implementation Method 3
the machining laser beam emerging from a laser beam source or one end of a laser optical fiber is focused, for machining a workpiece, onto a workpiece to be machined
Implementation Method 4
the material of the workpiece in the region of the vapor capillary heats up so much that it vaporizes
Data Source
AI summary
A method for determining a depth of a vapor capillary during laser machining includes: irradiating a machining laser beam onto a workpiece to form the capillary, the beam deflected by a first deflection device along a machining path within a first scan field, irradiating an optical measuring beam onto the workpiece, the measuring beam deflected by a second deflection device relative to the machining laser beam along a scanning path within a scanning area and then together with the machining laser beam by the first deflecting device, acquiring measured distance values along the path based on part of the measuring beam reflected by the workpiece, determining a depth/position of the capillary based on the acquired measured distance values. The scanning area size is based on a position of the laser beam and/or deflection of the laser beam by the first deflection device. A corresponding laser machining system is also provided.