Interferometric Welding Head Power Balancing for Stable Signal Quality
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Solution Overview
Problem
Existing workpiece processing machines face challenges in maintaining optimal signal quality and signal-to-noise ratio during interferometric measurements, particularly in laser welding, due to varying light conditions and reflectance differences between the workpiece and retroreflector, which affects the accuracy of measurements.
Innovation Solution
A workpiece processing machine equipped with an optical interferometer and a control unit that adjusts the power ratio between the measurement path and reference path by changing the power portion reflected from the retroreflector, using adjustable elements such as beam splitters, attenuators, and focusing units to optimize the signal quality and adapt to different reflectance conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the source power of the beam source is increased to improve signal quality, then the signal-to-noise ratio improves, but the dynamic range of the detector is exceeded and saturation occurs
Solution Approach 1:
A beam splitter unit is introduced as an intermediary element between the beam source and the measurement path. This beam splitter divides the source power into a reference path and a measurement path, allowing the reference path to carry a reduced power portion that prevents detector saturation while the measurement path maintains sufficient signal quality for accurate interferometric measurements
2Object-affected harmful factors
If the source power is reduced to avoid detector saturation, then detector saturation is prevented, but the signal quality and signal-to-noise ratio deteriorate
Solution Approach 1:
The optical path is segmented into two separate paths: a reference path and a measurement path. The beam splitter unit divides the source power between these paths, with the reference path receiving a reduced power portion that prevents detector saturation, while the measurement path receives sufficient power to maintain high signal quality for accurate workpiece measurements
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 solution enhances signal quality and stability by dynamically adjusting the power ratio, reducing artifacts and improving measurement accuracy, allowing for more precise control of machining parameters and increased process stability during welding.
Implementation Method 1
an optical interferometer, in particular an optical coherence tomography unit, comprising: a beam source for generating radiation having a source power, a beam splitter unit for splitting the source power of the beam source between a reference path, in which a retroreflector is arranged, and a measurement path, in which the workpiece is arranged, and a detector for detecting a total power of the (interfering) radiation
Implementation Method 2
a beam splitter unit for splitting the source power of the beam source between a reference path, in which a retroreflector is arranged
Implementation Method 3
a detector for detecting a total power of the (interfering) radiation, which is reflected and/or scattered to the detector from the workpiece in the measurement path and from the retroreflector in the reference path
Data Source
AI summary
A workpiece processing machine that includes: a beam emission head for providing a beam for processing the workpiece, an optical interferometer for splitting, redirecting, and detecting the beam, an adjustment element for changing a second portion of a power of the beam redirected from a retroreflector to a detector, and a control unit for actuating the adjustment element to control a ratio between a first power portion of the beam redirected from the workpiece to the detector and the second power portion of the beam redirected from the retroreflector to the detector to a target ratio.